Abstract:With the distributed transfer function method, a closed-form solution is obtained for free vibration and stability of a multiple-step beam under stepped axial pressures. According to variations of the geometry of the cross-section, the material and the axial pressure in axial direction, the beam is divided into multiple sub-beams whose closed-form solution is obtained with the distributed transfer function method. The natural frequencies and buckling loads along with their mode shapes are obtained by using the displacement continuity conditions and force balance conditions between the sub-beams. The method was validated through numerical examples of three-step beams. The natural frequencies of multiple-step beams under different axial pressure in each section were calculated with the example of four-step beams.

Abstract:The autonomous formation reconfiguration of Distributed Satellite Systems is one of the typical missions of autonomous control. Formation reconfiguration of distributed satellites was divided into two aspects: relative orbit control and overall planning. Furthermore, a uniform description of formation reconfiguration was presented. Then the problem of Agent-based autonomous formation reconfiguration was discussed in the hierarchical control architecture of distributed satellites, and the implementation framework in ObjectAgent is introduced. A novel spiral control scheme was raised for relative orbit regulation, and the cost budget was estimated. Auctioneering algorithm was adopted for position allocation. Simulation results show the effectiveness of Agent-based autonomous formation reconfiguration.

Abstract:The solid fuel ramjet is related to the missile flight conditions through the inlet. Compared with other kinds of ramjet, the marked characteristic of the solid fuel ramjet is that its propellant combustion chamber process is not only concerned with the propellant composition, motor structure and combustion pressure, but also dependent on the air parameter in the combustion air inlet. Hence, the operation process is rather complex. The operation process simulation model, the first of its kind in China, was established, and the effect of the missile flight mach number and height on the motor performance was discussed.

Abstract:Under the severe demand of the Water/Metal Fuel Motor on the flux of water in the starting period, a new type of pressure-adaptiveand flux-constant orifice was brought forward. The flux-constant principle of this orifice with pressure-adaptability was analyzed theoretically. Experiments were carried out. Their results show that the orifice can satisfactorily adjust the flux resistance automatically and keep the flux constant.

Abstract:The shortcomings of active positioning mode of Chinese Beidou navigation satellites system are introduced while a new technology is proposed on the basis of time difference carrier phase (TDCP) for RDSS/SINS tightly coupled integration. The TDCP measurements are used as the observation of Kalman filter to establish a tightly coupled integrated navigation system that works in passive mode. The principles and mathematic model of TDCP are described and a Kalman filter for integration is designed. Static and dynamic state tests were performed to validate the algorithm and evaluate the accuracy. The results show that the accumulation of velocity errors and position errors are attenuated remarkably.

Abstract:The inner flow field of scramjet combustion chamber with fuel jet and cavity structure was simulated numerically on the basis of the 3 D Navier Stokes equations. Finite differential method was used. With a comparison between the numerical and experimental results, the unsteadiness of fuel jet and influence of cavity structure on the flow field were discussed. From the results, it is observed that the stable flow field of numerical simulation is similar to experimentation, and the unsteady dynamic phenomenon that fuel jet moves downstream and diffuses into the cavity is captured from simulation.

Abstract:This paper established dynamic mathematical models of simulation modules of the space propulsion system in the whole operation process, which include liquid pipeline module, triple link module, filling in pipeline module, thrust chamber module and so on. The lumped parameters method is employed, aiming at synchronously considering the inertia, viscosity and compressibility of liquid. Thus the ordinary differential equation set built in the research can generally reflect the distributed characteristics of the operation process in the supplying system.

Abstract:The effect of strain rate in 1/4 model on blast scaling law was analyzed. The scaling method of simulation explosion test was studied by numerical simulation. Results from the simulation show that similarity of concrete slab subjected to the blast loading can be approximately obtained by using replica scaling law. The mesh size effect on the simulation was investigated. It is found that 4cm meshing results in worse deviations. The errors partly come from the local damage model for the concrete, partly from the coarse meshing.

Abstract:By the analytic method, the control of V-bar departure in rendezvous and docking under the field of view constraint was studied. The basic maneuver strategy of V-bar departure using radial impulse was described. This strategy fulfils the requirement of minimum plume impact on the target and trajectory safety. The analytic solution calculating the maximum field of view using radial impulse and calculating the permitted impulse using field of view was developed on the basis of CW equation while the solution with the formulas to calculate the time of the maximum field of view and the departure distance in the V-bar direction was also developed. Finally, the comparison between numerical and analytic method shows the method developed in this paper is correct.

Abstract:Based on the gridless SPH numerical technique of Ls-dyna hydrocode, the characteristics of debris clouds originating from impact of spherical projectile on the plate at different velocities were simulated. At the same time the different physical courses due to various impact angles were obtained. The simulation results show a good agreement with those from the experiments presented in the literature concerned. The generation and expansion of debris clouds were clearly simulated. It indicates that the SPH algorithm can make the qualitative description for phenomena of hypervelocity impact, thus proving the feasibility of the numerical simulation of hypervelocity impact on the basis of the SPH algorithm.

Abstract:The research is based upon a self-developed impulse radar experiment system, whose essential technologies include multiplex correlative pulse combining pulser, quadrature demodulation sampling receiver, signal processing system and pulse radiating and receiving array antennas and so on. The detection experiment of stealthy targets in the outdoor was carried out by the system. Its results indicate that the impulse radar has the powerful capability of anti-shape stealth and anti-material stealth.

Abstract:A single ridged wave-guide slot phased antenna (SRWSPA) with a photonic band-gap structure which is alternately arranged on the antenna is presented. Another antenna with identical dimensions on a metal ground plane is also included, so that a direct performance comparison can be made. Measured data shows an obvious improvement of radiation pattern, a reduction of coupling coefficient between elements, a significant reduction of back lobe and an improvement of scanning performance. Meanwhile it also proves that the structure is more effective to suppress the surface wave than the choke ring. This is significant in improving the radiation performance of the single ridged wave-guide slot phased antenna.

Abstract:A quantum secure direct communication protocol and a multiparty quantum secret sharing protocol based on Einstein-Podolsky-Rosen pairs and entanglement swapping are presented. The present quantum secure direct communication protocol makes use of the ideal of block transmission. Different from the proposed quantum secure direct communication protocols, the sender can encode one'ssecret message as one of the four Bell states without ensuring the security of the quantum channel firstly. In the multiparty quantum secret sharing protocol, the communication parties adopt checking mode or encoding mode with some probability. It does not need multi-particles entangled state but only Einstein-Podolsky-Rosen pair to realize the protocol. Compared with the proposed quantum secret sharing protocol with entanglement swapping, it is unnecessary for the protocol to perform local unitary operation. The efficiency for the protocol is greatly improved. The securities for both the protocols are the same as that for BBM92 protocol.

Abstract:Raw signal simulation is considered the base for the study of distributed small satellite SAR system. Huge computation is needed when raw signal of wide area natural scenes is simulated. A rapid algorithm using FFT is proposed to reduce computation. Firstly, time domain response of the natural scene is approximately expressed by pulse sequence. Then in frequence domain, LTI filter is realized with FFT to generate raw signal. The results of SAR imaging and interferometric processing of simulated raw signal validate the algorithm.

Abstract:An efficient target detection algorithm for infrared sequence image with sea-sky background is presented. For the big none-Gaussian noises and the none-linear movement of the target, the algorithm is established mainly on the basis of the Sequential Monte Carlo (SMC) method. The algorithm uses the statistic values of the target's feature image to change the weight of the particles which are produced by Monte Carlo sampling, and the target is detected and tracked based on the control of these weights. The difference image is used as the feature image. The experimental results demonstrate the effectiveness and real-time efficient of the algorithm.

Abstract:Regarding the problems of singularity while using classic orbital elements in satellite bearings-only passive tracking and the lack of physical meanings in measurement equation's variables and their corresponding coordinate transformations, a new satellite-to-satellite extended Kalman filtering (EKF) tracking method with bearings-only measurements in J2000.0 ECI frame is put forward. An explicit definition of the variables and their coordinate transformations in measurement equation are submitted. Moreover, the state propagation stage, state transfer matrix and measurement Jacobi matrix are deducted in detail. Performance is contrasted and validated through simulated data from STK6.0 with various initial state errors and angles measurement errors. Simulation indicates that it is possible to passively track low earth circular orbit satellite (e=0) by a high earth orbit satellite (quasi-geosynchronous orbit satellite) with bearings-only measurements. When the angles measurement accuracy exceeds the average angles changing magnitude, the convergence time and the tracking errors rapidly decrease. Moreover, the method also shows resilience to varying initial state errors.

Abstract:Based on the rough set model proposed by Pawlak, a new fuzzy C-means algorithm-rough fuzzy C-means algorithm (RFCM) is presented. The algorithm employs a new objective function which incorporates the concepts of the upper approximation and the lower approximation in rough sets, and which produces better results than Fuzzy C-mean algorithm at time complexity, clustering precision, the sensitivity to initial degree of membership matrix. The better effect can be testified by many experiments.

Abstract:An optimal model is presented in this paper, aiming at facilitating cost effective effort allocation among software components so that a quantified system reliability goal is attained. The software reliability is defined as a function of component failure intensities, the operational profile, expected component utilizations and the stated mission time for failure-free execution. The details of building the optimal model and the steps of the solution are presented. In the process of solution, nonlinear programming theory can be used to solve the optimal model. Finally, a simple example is provided to show the feasibility of the optimal model for the allocation of software reliability and cost.

Abstract:A new QoS mechanism with effective multicast supporting in high performance routers—QoS_RESM is presented and studied in this paper. Based on multi-threshold mechanism, it considers the congestion information of remote forward engines by introducing the mechanism of global control information feedback. It ends with a description of the implementation method of QoS_RESM in the core router on the basis of network processor.

Abstract:The homo-dimer, homo-trimer, homo-tetramer, homo-hexamer of proteins were classified with a new encoding method—encoding on the basis of grouped weight (EBGW) and component-couple algorithm. It was found that the overall classification accuracy by Jackknife test was 70.92%, which was 20.28 and 7.53 percentile higher than that of the amino acid composition and that of the weight pseudo-amino acid composition method with the same classifying algorithm on the same data set. The results indicate that EBGW method has reached a satisfying performance despite its simplicity.

Abstract:Operating principle and developing procedures of a time-domain measuring system of radar target are introduced. Digital Sampling Oscilloscope is used for measuring in compact range for the first time. The theory of time domain measurement was studied and the structure of the system and flow diagram for measuring were given. Programs for controlling of the oscilloscope and turntable as well as data processing were developed, based on which an entire measuring system of UWB compact range is achieved. Finally, some data measured and processed by the system are presented.

Abstract:The measurement model of tracking a ballistic target of coast phase in the LEO space-based infrared constellation was constructed. A suitable accurate target motion model was developed. Considering the robustness of the nonlinear filter, a square root version of the UKF was included. It was corroborated in the theoretical analysis. The simulation shows that the square root UKF (SRUKF) has good performance when tracking a ballistic target in the LEO space-based infrared constellation.

Abstract:Some typical methods for human reliability analysis are surveyed. Firstly, the definition of human reliability is discussed. Secondly, several typical methods are chosen from the first generation methods for comparison and review. Their basic characters and limitations are discussed. Thirdly, two typical methods of the second generation are analyzed in detail. The comparison between the above and the preceding methods is carried out while their advantages and drawbacks are presented. Finally, further research suggestion is proposed.

Abstract:Optimality analysis of linear programming is used extensively in economy and management. The optimal objective value is a complicated piecewise linear function of the right-hand-side vector of the constraints, and its analytical expression is normally hard to obtain. Four metamodels, that is, polynomial regression, radial basis function, Kriging interpolation, and polynomial regression hybridized with Kriging interpolation, are used to rapidly predict the optimal objective function value. Comparative analysis through simulation experiments shows that the last three methods can provide higher accuracy fitting with fewer experimental designs. In particular, polynomial regression method hibridized with Kriging interpolation can not only have a good fitting accuracy but also give a simple approximate expression of the optimal objective function value using a second-order polynomial. The results show that the metamodel method is effective for optimality analysis of linear programming.

Abstract:To deal with the problem of Debris' feature extraction with the characteristic of large scale number in description parameter and nonlinear relationship among these parameters, a KPCA-based method is presented. Based on the detailed introduction of KPCA algorithm, a real case was studied for the purpose of constructing a debris automatic recognition sub-system which can be served for diesel engine fault detection and analysis system. The results of experimental research and a comparison with linear PCA demonstrate that KPCA-based approach is feasible and valid for synthesizing nonlinear characteristic parameter and reducing feature dimension.

Abstract:In view of the fact that the multiple constrained QoS multicast routing is a NP-Complete problem, a controllable strategy for decomposing and composing multicast tree is introduced. Different trees of little cost will be gained under the strategy, so that the problem of local best can be solved effectively. An ant colony algorithm, which divides the ant colony into ant assembly according to the ends of multicast, is designed on the basis of the strategy. The pheromone updating mechanism is improved with the “dead-point” punishment and the encouragement and punishment to the multicast tree strategy, so that the algorithm can converge fast. Simulation results demonstrate that the method can solve the QoS multicast routing problem effectively, and perform well as the size of network increases.

Abstract:Coupling coefficient will directly influence the light distribution of linearly polarized light through the Fused-Tapered zone of Polarization Maintaining Fiber(PMF) couplers. Accordingly, it affects the coupling performance of the couplers. Coupling model of fused polarization-maintaining fiber couplers is built on the basis of coupling mode theory of optical waveguide. A new formula for coupling coefficient of PMF couplers has been derived. It is appropriate for any PMF when the core is circular and the birefringent axes are nonaligned. The conclusion of the research can provide the precondition to solve the coupled mode equation and analyze the performance of couplers. Therefore, theoretical direction for the high-performance manufacturing of PMF couplers is provided.