Abstract:An improved de-coupled solver of non-equilibrium flow was used to split the Euler equations for a reacting flow. Inviscid flux was calculated with fifth-order WENO scheme. Trapezoid formula and α-QSS methods were applied to deal with the stiffness generated by the chemical reacting source term of species equations separately. Time integration was performed with two-order TVD Runge-Kutta scheme. Cellular detonation of H₂/O₂/Ar in a straight tube was numerically studied. Calculated results by different methods were similar, and triple point structures were analyzed. The releasing heat of chemical reaction dealt with by α-QSSmethod is higher than that by trapezoid formula, so the detonation wave propagating speed of α-QSSmethod is higher than that of trapezoid formula too. Development of cellular structure was elaborated. Due to interactions between transverse waves and between transverse wave and tube wall, re-initiation was ignited, which plays a crucial role in the propagating of detonation wave. Ratio of numerical cellular structure length to width is consistent with reference value, which indicates the feasibility of the numerical method.

Abstract:Supersonic ejector is an important component of the high altitude test facility. Evacuating the test cell before engine start by the ejector can arrest the rocket exhaust leak into the cell, thereby prevent the potential exhaust separation in the rocket nozzle. Meanwhile, the start phase of the ejector is the most critical condition for ejector operation, and an ejector designed improperly will result in an unacceptable high starting pressure and inability to be started of the ejector. In order to investigate the starting performances under this condition, a test facility for small scale supersonic air ejector is constructed. By using pneumatic method and schlieren technology, the flow field is studied when the ejector on utmost starting pressure ratio. The result shows that the utmost starting pressure goes down with the mixing-room contraction ratio. The low mixing-room contraction ratio will cause the ejector unable to be started as well as insufficient ejecting pressure. It is observed that the chamber pressure will go up monotonously with the ejecting pressure when the inability of the ejector is induced by low mixing-room contraction ratio. In contrast, if the ejector unstart is induced by insufficient ejecting pressure, the chamber pressure will go down with the ejecting pressure.

Abstract:According to the fixed-time hard rendezvous with chase spacecraft in high eccentric orbit, a new algorithm was introduced to solve multiple-revolution Lambert problem, which can find the optimal transfer orbit quickly. The solutions of multiple-revolution Lambert transfer problem were researched, and the relationship between transfer time and transfer orbit elements was figured out while the optimal rendezvous problem without time constraint was also studied. The calculation results for fixed-time rendezvous validate the correctness and high-level efficiency of the algorithm.

Abstract:The trajectory safety characteristic of space rendezvous was studied. First of all, the quantitative performance index of space rendezvous trajectory safety was proposed. The 3σellipsoid of relative position dispersal resulting from the navigation errors and control errors was investigated to describe quantificationally the relative trajectory safety between chaser and target vehicles. And then the orthogonal design of experiment method was adopted to analyze the influence of the transfer time, the number of impulses, and the intervals of impulses on the trajectory safety characteristic. The results show that the transfer time is the most significant among all the factors, the number of impulses is the secondary, and the interval influence is very small. Finally, the influence of initial rendezvous condition was analyzed by numerical simulation, and the results illustrate that -R-bar coplanar rendezvous makes the trajectory safety index the smallest. Furthermore, the influence on fuel consumption was analyzed, and the effect is opposite to that on safety index. The study points out the direction of the design of safe rendezvous trajectory, and provides the way to design the multi-objective optimal rendezvous trajectory.

Abstract:Three dimensional parametric finite element analysis models were created for typical high density BGA (Ball Grid Array) package to analyze the structure deformation and stress when loading steady temperature upon packages with different sizes. A simplified model for series analysis including equivalent beam and critical solder ball was established to analyze the effect of design parameters upon the mechanical properties of the package. The numerical results reflected the stress distribution and varying traits of the package, main parameters affecting the deformation and stress were identified. The method developed is convenient and effective. Also it can be applied for analysis of different types of BGA, or can be used for different analysis purpose, and is of certain reference value for the design and optimization of such kind of packages.

Abstract:Free-floating flexible manipulator system has become a nonholonomic system subject to the constraints of the conservation of angular momentum. The dynamic model of the nonholonomic system is usually the differential algebraic equation which is difficult to solve. So the free-floating system is translated into holonomic system in this research. First, the attitude of carrier was supposed to be controlled by torques. As a result, the system turned to be holonomic because the constraint of the conservation of angular momentum need not be satisfied, and the dynamic equations of the holonomic system were deduced based on Lagrange method. Second, the dynamic equations of free-floating system were obtained by putting the attitude control torques into zero. Finally, the dynamic equations were solved with numerical method. The numerical result is compared with the simulation result in ADAMS and the effective of the model for free-floating flexible manipulator system is verified.

Abstract:The bull whipping phenomenon in the deployment process of a large parachute was analyzed. Based on its character, the dynamic model of the whole process was built in five stages. At first, the basic model and restriction model were built respectively. Through their combination, the dynamic model of multibody systems of every stage was built. Then by connecting the dynamic model of five stages, the dynamic model of the entirely deployment process was accomplished. Through analyzing the results of simulation, the canopy displacement and shape, the velocity of top segment canopy, departure distance and tensile force distributing of canopy and lines when forming the bull whipping phenomenon are educed, some important and character data of the bull whipping phenomenon are summarized. The conclusion can provide reference for the engineering design department to designing, improving and using the large parachute.

Abstract:Based on the technology of Nano-based Planar Laser Scattering(NPLS), the ambient flow field of a cavity was studied in the research, in which the ethene fuel was injected perpendicularly in the upper part of a cavity placed in a scramjet engine model. The study focused on the mixing process of the fuel jet and its mainstream, the comparison of the changes in the fuel jet penetrability under different injection stagnation pressures, as well as the effect of the cavity geometry parameters on the mixing process of the fuel jet and its mainstream. Through the study, the effect of the injection stagnation pressures on the mixing of the fuel jet and its mainstream was found mainly in two aspects: the penetrability and the diffusion of the fuel jet. As for the fuel jet, this study indicated that the main phase of the mixing process with the mainstream begins when the eddies come forth and ends when the eddies break up. Moreover, this study showed that a closer location of the injector helps to produce a better mixing of fuel jet and mainstream and a higher-quality transportation of the fuel jet to the cavity. In addition, the influence of the cavity configuration on the fuel jet primarily starts from the stage of the breaking up of the large-sized eddies.

Abstract:An adaptive notch filter design that considers the body-bending vibration associated with the attitude control of a solid launcher is discussed. The problem of obtaining a notch filter from a given signal was first formulated as the conventional problem of system identification. Then the proposed adaptive notch filter was developed via the algorithm of Steiglitz-McBride. The new adaptive notch filter exhibits fast convergence speed and an excellent capability to frequency tracking in signals. Applying this adaptive notch filter to the launcher results in stable response characteristics of the attitude control system, which is unstable without adaptation.

Abstract:Under GNSS autonomous navigation mode, traditional system cannot support integrity services. Therefore, a GNSS autonomous navigation integrity weighted technique based on crosslink has been developed, using the modified weight matrix of robust M-estimator for crosslink range degrading by failure satellite. Results show that it can ensure autonomous navigation services precision with continuous stable autonomous orbit determination and time synchronization. Simulation of this technique suggests that it can effectively remove effects of autonomous orbit determination by failure satellite, which has the same orbit determination precision of healthy constellation.

Abstract:Wireless cognitive network is regarded as one of the fundamental architectures of next generation wireless network. It can solve the key problem of increasing demand for spectrum and low spectrum utilization. By opportunistically accessing the temporal available spectrum, the spectrum utility can be increased tremendously. As the spectrum utility is mainly determined by the spectrum allocation scheme, how to efficiently allocate the spectrum is always one of the fundamental aspects of wireless cognitive research domain. We have proved that the optimal spectrum allocation problem under heterogeneous spectrum availability is NP hard. To solve the spectrum allocation problem efficiently, a new spectrum access approach was proposed which is based on the distributed maximum weighted independent set algorithm——DMWIS. The time complexity of this algorithm is O(V²/2). By detailed simulation, the algorithm can be finished within 3 rounds under 90% of the random network scenarios. The performance of this algorithm can reach 90% performance of optimal algorithm.

Abstract:A parallel simulation model for message passing applications on multi-core cluster systems was presented, then a parallel simulator MCPSim (Multi-core Cluster Parallel Simulator) was designed and implemented. MCPSim adopted a three-layer (i.e., Intra-CMP, Inter-CMP, and Inter-Node) message passing model in its functional and timing model. Furthermore, MCPSim implemented a profiling module to obtain message distribution percentage in the three layers. The current research selected several benchmark applications including PRIME,Jacobi3D, NPB IS and HPL to validate MCPSim. Results show that MCPSim is more accurate than BigSim in performance prediction and can be used in the performance analysis of message passing applications on multi-core cluster systems.

Abstract:The study proposed the polarization array in anti-radiation seeker, which uses joint estimation of polarizational and spatial domains anti-decoy by the differences of the target and decoy. At first, it estimated DOA (direction of angle) and polarimetric parameters of radar and decoys, the DOA supply to guide the ARM and the polarimetric parameters apply to discriminate the radar or decoys, for the purpose of preventing decoy. Then, the all-trajectory simulation on ARM against three point sources bait is accomplished by combining ARM motion equation and guide equation. Many experiments on all-trajectory simulation are done by Monte-Carlo. The simulation results demonstrate the effectiveness on anti-decoy in anti-radiation missile using joint estimation of polarizational and spatial Domains.

Abstract:Space-filling curves are classical ways to reduce the dimensions of data. This paper first presents the mapping rules of the diagonal space-filling curve. Unique curve which exists under the rules and the number of grids on each dimensionality is not constrained. Then a new conception about equipotential surface was given, and the relationship between the number of grids on different equipotential surface was dirived. Table-based space-filling curve generation algorithms on the basis of the realtionship were presented. It is found that the algorithms have low running time and high scalability.

Abstract:Aiming at the problem of underdetermined blind separation of attenuated and delayed mixing communication signal, this paper proposed an algorithm based on shortest distance to estimate original signals, calculating the shortest distance from mixing signal vector to subspace spanned of mixture vector firstly. Then it estimated the number of active original signal simultaneously, translated the problem of underdetermined mixture into over-determined mixture, and completed the estimation of original signal by solving the over-determined equation. The efficiency of the algorithm is proved in theory. Computer simulations show that the proposed recognition algorithm is high in performance.

Abstract:The problem of direction tracking of target with varying direction based on antenna array was addressed, and the effect of mutual coupling was also considered. By exploiting the special banded Toeplitz form of the mutual coupling matrix of uniform linear array, the technique of appending assistant antennas at each side of the original array was introduced for mutual coupling compensation. After that, particle filters were used to obtain real-time direction estimates of the maneuvering targets based on the mutual coupling-compensated array output. Numerical simulations were carried out, showing the satisfying performance of the proposed method in direction tracking.

Abstract:For traditional CFAR detection, the detectors cannot adapt to homogenous and non-homogenous environment simultaneously, so a modified CAFR detector (IEGOS CFAR) is proposed based on greatest selection in this paper. Using the switching method, the local clutter power estimates in leading window and trailing window were obtained by choosing the reference cells adaptively, then the greatest of them was taken as the total clutter power estimate to realize the CFAR detection. Under the assumption of Swerling Ⅱ target and Rayleigh distribution clutter, the CFAR property was proved. Comparisons between CA, GO, SO ,OS and EXS detectors show that IEGOS owns better performance both in homogenous and non-homogenous environment caused by interference and clutter edge. The detector is suitable for application since no sample ordering is needed.

Abstract:Channel interpolation methods based on zero-padding DFT for OFDM systems were investigated. Two conventional interpolation schemes for channel estimation were analyzed. Analysis shows that the two methods are equivalent, and zero padding can be used to reconstruct the channel impulse response samples of length N, where N is the number of total subcarriers. The reconstruction error of conventional zero-padding methods was discussed, and a new zero-padding method was proposed. Simulation results show that the above analysis is correct, and the reconstruction error of channel impulse response is decreased by the proposed method in some channel conditions. Furthermore, the channel interpolation with the proposed zero-padding method is robust to the distribution of path delay, and the performance of system is enhanced.

Abstract:A sidelobe control method is proposed for robust adaptive beampattern based on worst-case performance optimization. Multiple quadratic inequality constrains are added to arbitrary sidelobe regions, which can achieve lower sidelobe level as well as adaptively suppress interference. The optimization model can be converted into convex second-order cone(SOC) programming issue, which can be solved efficiently using the existing interior point method. Simulation results demonstrate that in the case of beam pointing error, the approach proposed can obtain the prescribed low sidelobe without performance loss.

Abstract:C2 (Command and Control) organizational communication structure and its restriction of design were introduced. The design issue on a robust communication of C2 was discussed. Then the research proposed a robust design methodology of organizational communication structure based on Nested GA (Genetic Algorithms). The topology and the capability of link were searhed in the outer GA; the inside GA could calculate the average delay in the mission set which could be used to evaluate the capability of link in the outer GA as adaptability value. A numerical example and the cases show the performance of the robust design method proposed can achieve the design objectives.

Abstract:System cohesion is an important evaluation factor in information system architecture. Based on the architecture framework, the formal description of system interfaces and system functions were provided. In terms of functions and data relationships, the function cohesion and data cohesion were defined respectively, and the system cohesion evaluation method was proposed. Furthermore，an application example was presented．The method is helpful in system design, function assignment, and improving the quality of architecture development.

Abstract:The granular principles of exploratory analysis model was investigated, a granular computing-based exploratory model was constructed for the measurement of command and control system effectiveness. The paper focused on model construction, granular acquisition and attribute function formation in the exploratory model. For the minimizing of the mission completion time, the exploratory analysis experiment was designed, with reference to cases of multi-branch joint operations. The exploration shows that the exploratory analysis modeling based on granular computing can reduce the complexity by granular conversion and keep consistency of problem description on different granular levels.

Abstract:In order to generate C⁴ISR requirements systemically, systems must be classified in particular. However, the taxonomies of systems are still in their early stage, which is not adaptive to C⁴ISR requirements generation. Therefore, a three-dimensional (3-D) taxonomy, which is based on characters of C⁴ISR requirements and evolutionary rules of weapon materiel, is put forward. In 3-D taxonomy, weapon materiel were classified according to three levels of task illegibility, three levels of structure complexity, and three levels of technological uncertainty. Based on the hypothesis that C⁴ISR requirements generation must be adaptive to the type, it is suggested that C⁴ISR requirements generation comprise three modes, which are reproduction, discovery and creation respectively. They can provide the way to be exact, right and advanced respectively. The relation between the modes of generating C⁴ISR requirements and the types is presented. At last, an example is analyzed to illustrate the pattern. The example shows that the pattern is feasible and that C⁴ISR requirements can be generated systemically.

Abstract:The distributed cooperative situation analysis plays a significant role in the Campaign Planning of Joint Operations. Since the current environments of battlefields are so dynamic and full of uncertainty, the traditional methods of situation analysis deal with the uncertain, inconsistent and incomplete information in these contexts with limited capability. This paper proposes a novel approach for the distributed cooperative situation analysis based on the Dialectic Semantics of the Argumentation Theory. The approach analyzed and represented the claims of different participants, the attack relationships among the arguments from different participants, and the focuses of contradictions between different claims using the multilateral dialogue games, and constructed a Grid of Dialectical Analysis Trees to assist the decision makers to cooperatively solve the inconsistencies of their beliefs and the conflicts among their standpoints in situation analyses. This study will provide a new methodology for the situation analysis of Joint Operations.

Abstract:Lanchester equations that describe the “size effect” of casualties assume that the intra-structure of a force is perfect, which is sublated in this article. It puts forwards firstly an opinion formation dynamic model expressing the “synchronization effect” for value chain of combat of systems of systems (SoSs). It is a topological and characterized attributes-based methodology for presenting conceptions, such as battlefield variation, individual/shared cognition, self-synchronization and equilibrium in combat of SoSs, and the “synchronization fragility” of scale-free network under equilibrium is found in simulation of combat of SoSs.

Abstract:In order to satisfy the potential demand of exerting a subtle psychological influence on the people of opponent country in psychological warfare, an idea of psychological suggestion based on video superimposing (PSBOVS) was proposed in this paper. The producing and influencing mechanism of suggestive information was analyzed from the psychology support and video basic. The model of psychological suggestion effect process based on video superimposing was presented. The video modeling and parameter analysis were carried out for information producing while psychology factors were considered. Then, the contents and forms of suggestive information were analyzed from the point of information received, noticed, understood and accepted. PSBOVS can provide the theoretical guidance and decision support on how to encode suggestive information and influence the psychology of people effectively.

Abstract:More natural, effective and collaborative human-computer interaction is the request of human-computer environment in C2. In this paper, the elements of human-computer interaction in C2 were analyzed, and the concept model and system model of multiple and multimodal HCI were proposed. Based on the models, a prototype system was designed to accomplish the tasks of situation or intelligence analysis by two interaction channels, which are speech and two-handed gesture based on multi-touch. The improvements of naturalness, efficient and collaboration for the prototype system were proved with experiment and questionnaire, and the results show that the multiple and multimodal interaction in C2 is effective.

Abstract:Efficient search in decentralized peer-to-peer systems is a challenging problem. An intelligent search mechanism based on topology evolution, named ITSON, is proposed. Each peer clustered with peers in similar interests into a community and chose important communities as logical neighbors based on the past queries. For a new arriving query, the most possible communities that have the query answers were selected according to topology evolution to send the query. With queries done, overlay network topology can be adjusted automatically with little cost. Simulations reveal that ITSON greatly improves the search efficiency and guarantees the search effectiveness.

Abstract:The problem of disaster monitoring satellite (imaging satellite) scheduling based on CHARTER mechanism is researched. At the very beginning the mechanism on which CHARTER is working was introduced. The problem was taken as a rescheduling problem against area targets according to the mechanism. To observe effectively, a dynamic partitioning algorithm for area target was proposed, and a dynamic rescheduling algorithm was raised to support satellite re- rescheduling. Finally an example was constructed to testify the correctness and validity of the algorithm proposed.

Abstract:In group decision-making problems with linguistic comparison matrices, different decision makers may use linguistic term sets with different granularity and different semantic to represent their preferences. A new approach to deal with this issue was presented, which uniform the linguistic term sets with multi-granularity and multi-semantic into the normalized representations of two-tuple linguistic. It was approved that by this approach there is no information loss and the linguistic comparison matrix can keep its properties after unification. Then, based on some aggregation operators of 2-tuple linguistic, different decision makers' preference information was aggregated into the group preference information and most desirable alternative is selected. An example was presented to validate the proposed method.