Abstract:Theoretical investigation on the behavior of boron particles in the flow field of a ducted rocket secondary combustor is presented. The study was motivated by the difficulties in achieving good combustion efficiencies of boron particles. The equation describing the gas flow field and the particle behavior were solved numerically. It is presumed that the ignition and combustion of boron particles can be controlled by King's model. The solution presents the trajectory and oxide layer thickness of the boron particles due to the interactions with the surrounding gas. Experimental investigations were done on a connected-pipe test bed. Decreasing the side-inlet angle increases combustion efficiency.

Abstract:Through the analysis on kinematical constraint characters of the launch window for Earth-to-Moon transfer trajectories based on the high elliptical parking orbit, laws of kinematical constraint influence on the launch window are given, and launch opportunities of the lunar probe and the probability to add the launch window are verified. According to the kinematical constraint characters of the launch window, a fast design method for the Earth-to-Moon transfer trajectory based on the high elliptical parking orbit is provided. The simulation results show that the analysis on kinematical constraint characters of the launch window for Earth-to-Moon transfer trajectories based on the high elliptical parking orbit is correct and the design method for transfer trajectory is effective.

Abstract:The dynamic characteristics in the abnormal operation process of the gelled propellant space power system is dealt with in this paper. For the purpose of setting up the fault patterns of the space power system, the fault property equations and the normal mathematical models in the operation process were built. Then, four faults, including pipeline leak, filter jam, valve fault and nozzle ablation, were simulated by the visual C++ software. With an analysis of the results, some foundation for the intelligent fault diagnosis of the space power system in the future is provided.

Abstract:For the attitude control problem of terminal approach phase of RVD, the feedback linear theory was adopted to linearize nonlinear attitude dynamics, and a phase-variable states space model was deduced. The terminal sliding mode control theory considering the disturbances was used on the basis of the deduced model. Furthermore, this paper introduces a controller which implements the attitude tracking and controls the states tracking errors convergent to zero in the finite time. For the example given, the control results satisfy the terminal time constrain and the tracking errors were convergent to zero, and this demonstrates that the controller is robust.

Abstract:Silica sols were synthesized by an acid-catalyzed sol-gel process and fluoro-acrylate polymer/SiO₂ hybrid materials were prepared by the in-situ polymerization and blending method. The structure, morphologies of the hybrid coating and the dispersion of SiO₂ in coatings were characterized by FT-IR and SEM. The effects of content, distribution and interfacial conditions of inorganic disperse phase on the surface and mechanical properties of hybrid coatings were investigated. It was found that in the hybrid coatings, SiO₂ subsisted in networks, and covalent linked with organic components. The dispersion of SiO₂ in coats prepared by in-situ polymerization method was better than that by blending method. The water contact angles were enhanced with SiO₂ content for the coatings by the two methods, while in the same SiO₂content, the properties for the coatings by blending method were slightly better than that by in-situ polymerization method. The hardness and adhesion of the hybrid coatings had the same trend with the increase of SiO₂content, in-situ polymerization method was better than that by blending method.

Abstract:The thermal IR images of camouflage net were recorded at different time in a day. The influence of sunshine on IR pattern of the camouflage net was discussed. The solar energy absorptivity of the camouflage cloth of the nets influences the IR pattern under sunshine greatly, and the influence even exceeds that of thermal IR emissivity. The dark green cloth of camouflage net, whose thermal IR emissivity is lower than that of khaki cloth, absorbs more solar energy. When the emissivity difference between khaki cloth and dark green cloth is less than 0.11, the apparent temperature of dark green cloth may be equal to or higher than that of khaki cloth in the sunshine. When the emissivity difference between khaki cloth and dark green cloth reaches 0.27, the apparent temperature of dark green cloth is lower than that of khaki cloth in the burning summer sunlight.

Abstract:The SiC coating was deposited on the SiC fiber through CVD routine, and the effect of deposition time on the fiber performances was investigated at initializations such as 2h, 4h, 6h and 8h. The results indicate that the fiber without coating showed better mechanical properties than those with coatings. The coating, of which the thickness increased with the lengthening of deposition time, altered from island appearance to continuous layer appearance at the same time. Furthermore, the single fiber strength displayed a raise-and-down tendency.

Abstract:Methacrylic acid-methacrylonitrile-methacrylamide(MAN-MAA-MAM) copolymer was synthesized by using peroxide as initiator and methacrlic acid, methacrylonitrile and methacrylamide as main raw materials. The cycle-reaction of the MAN-MAA-MAM copolymers at high temperature and the thermal-properties of polymethacrylimide（PMI） were investigated. The results show that the cycle-reaction temperature of MAN-MAA-MAM copolymer is 160℃ and PMI is stable at 280℃ in air.

Abstract:The conversion process of the polycarbosilane (PCS) into silicon carbide (SiC) was investigated by TG-DTA, infra-red spectrum analysis (IR) and X-ray diffraction (XRD) etc, which indicated the quasi ceramic characteristics of pyrolyzates treated at 600℃. The carbon fiber reinforced silicon carbide (C_f/SiC) composites were hereby prepared at 600℃ through precursor infiltration and pyrolysis (PIP), and polycarbosilane (PCS) acted as precursor, carbon fiber as enhanced fiber. The results show that bending strength of 3D-C_f/SiC composites are 193.69MPa, room tensile strength 197.69MPa, high temperature(600℃) tensile strength 167.33MPa. Noticeably, the density of 3D-C_f/SiC composites is just only 1.27g/cm³. Furthermore, the fracture surface and microstructure were analyzed and discussed too.

Abstract:To overcome the shortcomings of traditional techniques for non-intrusive debug and optimization, the on-chip trace system was adopted to record run-time information of embedded processor with special hardware. To fill the vacancy of former study, this paper gives a deep view of the mechanism, characteristics and applications of on-chip trace technique with TraceDo, an on-chip trace system of a multi-core SoC. The functions and structures of TraceDo were introduced, the working process of path trace was explained and trace applications were also discussed.

Abstract:Based on the characteristics of packet forwarding in application layer multicast (ALM), this paper proposes a high performance multicast mechanism, in which a NIC-based multicast mechanism is used to send multiple replicas of an ALM packet to different destinations with less CPU intermediation in comparison to the traditional host-based multicast mechanism. By adopting the mechanism, the CPU overhead and the number of times data packets are copied from host memory to NIC buffer. Theoretical analysis indicates that the new mechanism can reduce the delay and improve the forwarding throughput in application multicast. We have modified the NIC driver and added some corresponding APIs to network protocol stack in order to implement the proposed mechanism. Experimental results also indicate the feasibility and validity of this mechanism.

Abstract:The resistant gene of plants has conservative sequence. Probes were designed in terms of the sequences of known resistance gene. With the colony hybridization method, the genomic library of Dongxiang wild rice was screened and two candidate clones were obtained. The sequences were analyzed with the blast program to the GenBank database and a conservative NB-ARC domain was found in both of the sequences. The clones would be transferred into rice for a further analysis.

Abstract:Composite service models can be classified into four types according to the different management of their control-flow and data-flow, namely, centralized control-flow and centralized data-flow, centralized control-flow and decentralized data-flow, decentralized control-flow and centralized data-flow, and decentralized control-flow and decentralized data-flow. We also give our quantitative inference based on the mathematical models to the conclusion that the decentralized control-flow and decentralized data-flow model can reduce the whole message size and lead to lower response time in geospatial services composition. Our simulation confirms the conclusion.

Abstract:Although inter-domain egress is tunable by TIE, it is too complex to compute its parameters, and it is impossible to tune its egress on different traffic load. Accordingly, an adaptive tunable inter-domain egress selection algorithm (ATIE) is proposed. ATIE can satisfy traffic engineering and network robustness by tuning parameter T with current traffic load. Experiments demonstrate that our solution can achieve a good balance between control plane sensitivity and traffic engineering adapting to different network traffic load.

Abstract:A method of estimating the confidence interval for debris population using radar beam fence is described. Whether a debris object may cross the beam fence, that is, whether a debris has large enough inclinationand radar cross section or not, is actually detected and modeled as a (0-1) distribution. Using debris altitude data collected, the average probability of crossing the beam fence is obtained. The confidence interval for debris population is estimated by the Central Limitation Theorem. The validity of the method is verified by simulation.

Abstract:To make out the signal processing of neuron and neural system, researchers have worked on it for scores of years. In this paper, the responses of FitzHugh-Nagumo (FN) neuron model, which is stimulated by additive Gaussian white noise and weak sinusoidal signal, is investigated via numerical simulations. The time and frequency domain results show that there is stochastic resonance and a dimensionless frequency sensitive range of 0.2-0.8. Thus the model can help to detect the sinusoidal signal. In addition, the frequency sensitivity coincides with the findings in biology and is beneficial to disclosing the secret in the signal transmission of neuron and neural system.

Abstract:Sparse decomposition of signal can get sparse representation of signal, and then next disposal can use this sparse representation expediently. But sparse decomposition is very complex (NP problem). Particle swarm optimization is a kind of optimization algorithm using colony aptitude. Its theory is simple to be realized, and the result of searching is good. To reduce complexity of sparse decomposition and space of memory, particle swarm optimization is used in searching the best atom. Particle swarm optimization can increase the efficiency processing signal using sparse decomposition, and then this method can meet (or near) the request of real time. Examinations have proved that this method is feasible.

Abstract:A study on the signal processing methods of time-domain measuring system is presented. Firstly, the background subtraction as a method of signal pretreatment is introduced, and FFT and CT(Chirp Transform) were applied to a time-domain UWB compact range measuring system. In the end, a comparison was made between the efficiency of FFT and that of CT.

Abstract:A context based arithmetic coding of Lapped Biorthogonal Transform (LBT) coefficients is proposed. Aiming at the shortcut of precision and computation complexity of binary integer LBT in DSP implementation, a fixed point algorithm of LBT which fits parallel processing in DSP is proposed. There are 60 context models in the algorithm. The coder of entropy coding is MQ-coder. For the purpose of parallel processing, the MQ-coding is isolated from the bit plane scanning. Based on the characteristic of coding algorithm after isolated coding, a modified MQ-coder is designed. Meanwhile, the implementation in TMS320C6000 DSP of the algorithm is studied. Experiments show that the algorithm's coding performance is mostly the same as SPIHT and very competitive with JPEG2000. The tests on the hardware platform show that the algorithm is simple for parallel processing and the computation complexity is very low.

Abstract:As information technology security issues become more prominent, the network system security analysis is becoming increasingly important. The paper presents NEG-NSAM, a network security analysis method. Based on network parameters abstract and vulnerability correlation analysis, the network exploitation graph model was constructed, and the dynamic process of a gradual infiltration of the main threats to security objectives was characterized. For large-scale network environment, the simplified algorithm of network exploitation graph model was proposed. Finally, the NEG-NSAM was used to exemplify the network and verify the feasibility and effectiveness of the method.

Abstract:Feature extraction and clarity expression are two main problems in 3D flow visualization research. To solve these problems, a feature extracting based 3D streamline placement algorithm is presented. The algorithm ensures that the feature structures around the critical points can be described correctly, and the output result shares good clarity. The algorithm is comprised of three processes. Firstly, based on the fast detection of critical points, the critical points are classified according to the eigenvalues of their Jacobian Matirx，and the match between the critical points and the seed templates is performed. Secondly, the seeds points are ordered in priority, and streamlines are generated in physical space. Finally, in image space, the distance between streamlines is controlled by the preset threshold value, and the nearest streamline to the observer is held according to the depth detection, thus the display clarity is ensured.

Abstract:To measure the aircraft model attitude in the spin time, a method based on stereo vision is presented. We get the attitudes from a set of man-made signs on the surface of the model. From a pair of figures of the signs, their disparities are computed out. The design of the signs and the computation of the attitudes are presented in this paper. The man-made signs have good identifiability and the anchor points are accurate. Finally, the data of experiments to determine the aircraft model attitude are provided. Through the experiments, it can be concluded that the process of the computing is satisfactory, achieving high robustness. The measurement shows that the method discussed is useful for the experiments in the vertical wind tunnel.

Abstract:Conceptual model for describing military requirements of C⁴ISR plays an important role for modeling C⁴ISR requirements. Based on 　the analysis of the model for C² process, a conceptual model for C⁴ISR military requirements description is put forward. On the whole, the conceptual model comprises object, subject and modeling. At the same time, the common concepts and terminologies, which are often used to describe C⁴ISR requirements, are defined. With the help of the conceptual model for describing C⁴ISR military requirements, relations among these common concepts and terminologies are explained and clarified. Therefore, constraints and fundamentals for describing C⁴ISR military requirements are presented. Finally, an example about anti-air system is presented, which shows that the conceptual model is highly feasible and promising.

Abstract:Parallel Discrete Event Simulation (PDES) Systems demand a Declaration Management (DM) service and Data Distribution Management (DDM) service similar to those defined in HLA to realize model interoperability. In KD-PADSE, a high-performance PDES environment was implemented, and those services in a parallel structure based on event-scheduling using predication and object proxy techniques were realized. In an experiment carried out on a 10-node Linux cluster machine connected via 1Gbps switch Ethernet, 10 thousand attribute updates per second (wall clock time) was achieved in a synthetic benchmark test, which is 20 times larger than that of the same experiment without DDM services. The experiment proves the functionality and high performance of the implemented DDM service in a PDES environment.

Abstract:The measure of fragment's speed is a difficult problem in missile damaging-flight tests, and exact measure results are very important for the evaluation of weapon's damage effect and other technical parameters. Based on domestic actuality, the basic principles of the measure and evaluation methods of missile fragment's speed are summarized. The error sources of measure and evaluation of fragment's speed are discussed in each method discussed in the research. In view of the characteristics of the missile damaging-flight tests and the actual instance of the range, the error and error sources of single fragment's speed under the method of Reticulate Targets Method are analyzed. The corrected error model and the technique of improving speed measure's precision are put forward. The flaw and improving direction of the scheme normally used are pointed out. The results of the research have partially applied to the missile damaging-flight tests.

Abstract:Reasons that cause computational difficulties in collaborative optimization are analyzed and the COMI（Collaborative Optimization Based on Multidisciplinary Inconsistency） algorithm is presented．Relax constraints and system level penalty function are constructed based on inconsistency information between disciplinaries, and a GA optimizer is used to solve a typical MDO question．Simulation results show that the feasibility and the optimal value of COMI is more balanced than the standard CO algorithm and the relax CO algorithm．

Abstract:Let｛X_n｝ be a sequence of semimartingale in a filtered complete probability space (Ω，F，F，P) satisfying the usual condition. We use the general Girsanov thorem and closed graph theorem to prove that the sequence ｛X_n｝converges on X in the Emery topology w.r.t Q if｛X_n｝ converges on X in the Emery topology w.r.t P and the probability measureQ^loc《P. In light of this fact, we prove that if X is a d-dimensional semimartingale and a d-dimensional predictable process，H is X-integrable in the sense of vector stochastic integrals w.r.t P， when the probability measure Q^loc《P, H is also X-integrable in the sense of vector stochastic integrals w.r.t Qand these two integrals are Q-differentiable. It is noted that the condition of Q《P is stronger than that of Q^loc《P, therefore, this paper generalizes lemma 4.9 and theorem 4.14 in［1］.