Abstract:The navigation constellation's autonomous navigation requires the autonomously updating of the broadcast ephemeris. In view of the limited data-processing ability of the satellite, the forgetting factor recursive least-squares algorithm was introduced to improve the data-processing efficiency. Considering that the navigation satellite's orbit eccentricity is equal to zero approximately, it would result in the singularity of the normal matrix in the process of fitting. The new broadcast ephemeris parameters fitting algorithm was developed and the partial derivative matrix of satellite position vector with respect to modified parameter was deduced based on the non-singular transformation. Finally, the rationality of formulas and algorithm are validated by simulation.

Abstract:The current studies on optimal rendezvous trajectories for exploring asteroids always concentrate on the fuel-optimal two-impulse rendezvous, while the aim of this paper is aimed to investigate the multi-objective optimization problem of multiple-impulse rendezvous for exploring asteroids. A multiple-impulse rendezvous optimization model using Lambert algorithm for exploring asteroids including earth departure and heliocentric transfer phases was established, which utilized minimum-fuel cost and minimum-time transfer as two objective functions. The NSGA-II algorithm, a very representative multi-objective evolutionary algorithm, was employed to obtain the Pareto solution set. The effectiveness of the proposed optimization model and algorithm was testified by solving two asteroids mission design problems. The results show that the proposed method can effectively and efficiently demonstrate the relations among the mission characteristic parameters such as launch time, transfer time and total fuel cost, and analyze the influences of different impulse numbers, and also compare and evaluate different exploration missions. The proposed method has good application value for preliminary mission design for asteroid exploration.

Abstract:The theoretical model for wet steam condensation flow was established. Furthermore, numerical simulation results with wet steam condensation flow model were coincident to the experimental data of C.A.Moses, which validated the credibility and accuracy of the model. Then, numerical simulation on condensation flow process was carried out under different configuration parameters. The results show that appropriately reducing the convergence ratio ?, area ratio and increasing the ι/d of secondary throat can increase the total pressure recovery coefficient，which improves the ejector performance.

Abstract:First, the importance of developing hypersonic quiet tunnel facility and techniques was pointed out, and the basic characteristics of quiet tunnel were briefly discussed. Second, according to foreign and domestic experience and research results of developing quiet tunnel, the project about aerodynamic and structural research of mach 6 Hypersonic Quiet Wind Tunnel was presented. Furthermore, the design details of valves, settling chamber and slot exhaust of nozzle were proposed. Finally, M6HQWT design Mach number is 6.0, nozzle outlet diameter 120mm, T₀500K,P₀1-5MPa and operation duration 20-30s. M6HQWT is the first hypersonic quiet wind tunnel in China, and can be used for experimental teaching and basic scientific research.

Abstract:A new scheme of attitude control with active magnetic torque and aerodynamic stabilization torque was proposed for low-orbit micro-satellite (orbit altitude lower than 500km), in order to take full advantage of environmental torque. Simulation results show that the characteristic distance of satellite d_cc is the linchpin which influences the attitude control scheme. Suitable magnitude of d_cc should be chosen in order to meet the request of satellite attitude control system. All this shows that the satellite structure proposed in the current study has the potentiality of being used for experimental teaching and research.

Abstract:The working process of inlet under the condition of different given influencing factors in the inlet/combustor/nozzle integrated flow field was discussed. The effect of fluctuation of nozzle diameter on the inlet was investigated. We also explored the effect of time and space fluctuation of inlet exit pressure on the inlet. The operating characteristics of inlet with different interfering factors were achieved. The result showed that time fluctuation of inlet exit pressure can bring the non-uniform distribution of inlet exit pressure. The response time of space fluctuation was longer than the that of time fluctuation. The recirculation zone at the diffusers moved upward gradually when the nozzle diameter was reduced.

Abstract:A vectored mathematical model and stability of a near-space earth observation platform are presented in this paper. First, the reference frames and motion parameters of the platform was defined. Then, a nonlinear six degrees of freedom mathematical model in vector form of the platform was derived based on Newton-Euler principle. Finally, stability of the platform was analyzed by means of Lyapunov stability theory. The results show that the platform is asymptotic stability for the equilibrium. The longitudinal motion and lateral motion of the platform under initial disturbances are both composed of two non-periodic attenuation modes and an oscillation attenuation mode. The fast attenuation mode is related to the angular velocity motion and reflects the process of moments balancing, while the slow attenuation mode is related to the linear velocity and reflects the process of forces balancing.

Abstract:Space electromagnetic docking is characterized by such advantages as no propellant consuming, continuous reversible ability and no plume contaminations, thus ensuring a broad prospect of application. The control difficulties of space electromagnetic docking lie in nonlinearity, uncertainty and coupling, etc. Given these, this paper synthesized LESO, feedback linearization and robust H_∞control technology, designed a coordinated robust control and verified the performance and robust ability of the proposed control scheme through simulation. Simulation results show that the proposed control scheme is capable of observing all states, improving the robust ability to model error and external disturbance and performing good tracking control functions.

Abstract:The TT&C demand of TT&C Scheduling problem was analyzed and a model of TT&C Scheduling 0-1 integer programming was constructed. The model's facility constraints and satellite constraints were relaxed by lagrangian relaxation method, and an upper bound of lagrangian dual problem by subgradient optimization algorithm was obtained. Finally, two examples were tested. The results demonstrate the validity of upper bound obtained by subgradient optimization algorithm.

Abstract:A numerical method was used to study the relationship between the dynamic radial stress and the expanding velocity at a cavity wall in metal materials. The simulation results of the elastic-perfectly plastic and power-law model satisfied the theories' that proves the availability of the method. Then the influences of the strain-rate and adiabatic effects of the materials were analyzed by simulation. The results show that the predictions of penetration with the strain-rate and thermal effects of the materials corresponded well with the experiments. The penetration resistance will be overvalued if the thermal effects were neglected, resulting in slightly lower penetration prediction. The predictions of Warren's theory model are less than the experiments made in the current study because Warren's theory model accumulated the errors from compressibility but ignored the thermal softening.

Abstract:Transmission properties of periodic structured subwavelength cut-wire pairs in terahertz regime were investigated numerically using finite element method. Under the normal incidence, the resonant peak in transmission spectra was found with red shift by increasing width as the metal wire width increases. In comparison with the analytical model, it is shown that this phenomenon results from the coupling of Fabry-Pérot resonance and dipole resonan

Abstract:A new method of image restoration based in Fractional Fourier Transform (FRT) domain is presented. The blurred image including higher intensity Gaussian noise and chirp noise is transformed into FRT domain. Only when the noise FRT spectrum is well estimated, the required image FRT spectrum can be well separated and return to the space domain with the inverse ransformation. As a result, we find that the method simplifies the process of restoration and the blind restoration will be obtained when we know nothing about the degradation process affected by various factors.

Abstract:Scientific Workflow Management Systems (SWfMS) has become an effective platform for representing and managing large-scale complex scientific computing processes, which glue together a large number of complex applications for data management, analysis, simulation, and visualization, and then assist the scientists for scientific discovery. In this paper, the current studies of Scientific Workflow (SWF) are reviewed firstly, including SWF models, presentations, languages, composition, validation, scheduling and provenance, as well as fault tolerance and system security. Then, the latest studies in recent years are also discussed. Based on the analysis of the key technologies and the latest development, the drawbacks in this domain are pointed out and some suggestions towards the future development are made. Finally, the recent research status quo in China is presented and some suggestions are given.

Abstract:Stream processing model is a newly emerging parallel processing model, which is derived from media processing. However, as an important application of media processing, H.264 coding encounters problems during its streaming procedure. The main reason is that dependency limits the data level parallel exploitations. To solve this problem, data level parallel methods for different coding modules were developed by the analysis of coding algorithm. By adopting the method, key coding modules of H.264 can attain large data parallel granularity. Experiment results show that the data level parallel streaming inter/intra prediction, CAVLC, and the deblock filter can achieve outstanding acceleration.

Abstract:The key factors that affect Single Event Latch-up sensitivity were investigated. In view of 180nm bulk technology, based on calibrated CMOS inverter model, TCAD method was adopted to study the effects of particle incident position, temperature, and well / substrate contact position, NMOS and PMOS spacing and other factors on SEL sensitivity. Simulation and analysis shows that, SEL response varies greatly at different nodes, and the study identified the sensitive nodes of the CMOS inverter of SEL occurrence, and explored the relationship between temperature, well / substrate contact position, NMOS and PMOS drain distance and LET threshold when SEL occurred, then analyzed theoretically and summarized the reinforcement for reducing SEL sensitivity. The results can provide effective guidance to the anti-SEL design.

Abstract:Owing to the more obvious quantum tunneling effect, Carbon Nanotube Field Effect Transistors (CNFETs) take on different scaling property from that of silicon based Metal-Oxide-Semiconductor (MOS) transistors. The scaling properties of Conventional MOS-like Carbon Nanotube Field Effect Transistors (C-CNFETs), on the other hand, differ from those of Tunneling Carbon Nanotube Field Effect Transistors (T-CNFETs) due to different operating mechanism. As a result, study on the scaling property is one of the most important means of searching for the application potential of the device. The band-to-band tunneling, however, has not been taken into account in previous researches. A comparative study of the impact of band-to-band tunneling on the scaling property of C-CNFETs and T-CNFETs was carried out based on Non-Equilibrium Green's Function method. The research results reveal that these two kinds of CNFETs take on different or even opposite scaling properties. The research will offer a vigorous guidance for the device design to obtain a proper trade-off among area, speed and power in application.

Abstract:Retinex theory is a kind of technology for image enhancement, and its basic principle is to decompose the original image into the product of illumination and reflectance. Traditional Retinex theory generally assumes that illumination is smooth, while in actual scenes, because of effects of different reflection characteristics of targets and shadings, illumination is piecewise smooth, resulting in an edge blurred reflection image and generating halos. For the above problems, this paper proposes an improved image processing framework for Retinex theory. First, the illumination is estimated with piecewise smooth operator to eliminate the halo phenomenon. Second, illumination correction is introduced for adjusting the contrast of the image. Third, reflection correction is introduced for detail enhancement or denoising. In the end, this paper verifies the improved framework with image quality evaluating indicators for the validity and correctness. The experimental results show that the improved framework is effective.

Abstract:Bandgap reference is a fundamental component in modern analog/mixed signal integrated circuits. In CMOS process, because of the small β value, the base-emitter path of the bipolar junction transistor has a significant streaming effect on the collector current，which leads to a large drift on temperature for the bandgap reference. In this study, a current compensating technique is proposed to enhance the temperature stability of the bandgap reference, and the power supply rejection is improved with a noise feedback circuit. Experimental results in the 0.18μm CMOS process show that the temperature coefficient is 8.2ppm/℃ within the temperature range of -55℃～150℃ on the 1.8V power supply, and the power supply rejection is greatly improved, the DC power supply rejection ratio is -90dB.

Abstract:MANET routing model based on P2P has become a hot topic recently，but the research results have been mainly applied to small or medium MANET, without fully using of the advantages of P2P distributed share theory. As a result, there exist detour and inefficient problems. In light of this, a large-scale MANET layered share routing model based on P2P is presented. It introduces layered mechanism based on network physical topology to enhance network scalability on the basis of cross-layer optimization, expands P2P distributed share strategy into MANET Routing layer, and can solve the detour problem in the previous algorithm. The simulation experiment shows that this new routing model can greatly increase the MANET routing efficiency.

Abstract:Exploratory Analysis (EA) is a methodology for complex macroscopical problems under deep uncertainty conditions. Supportive tools are necessary for the successful application of EA. Current EA software is mainly designed for specific applications, and lacks generic and formal modeling capability. A general-purpose EA tool, called EASim, was proposed. EASim uses extended influence diagram as its formal modeling specification. Its functional architecture was discussed firstly. Then the analysis and solutions of several key technologies of EASim were presented. Its software structure, runtime snapshots and technological advantages over Analytica were also presented. EASim has been adopted by several military organizations, verifying its feability.

Abstract:Synthetic Aperture Radar (SAR) Tomography extends the capability of SAR systems and allows reconstructing the height profile of observed scene. The deramping, one of important processes of SAR tomography, was investigated and a new deramping method based on simulated interferometric phase was proposed. This method can avoid extra atmosphere phase and obtain excellent deramping result using low precise elevation of the target, so it facilitates SAR Tomography. Finally, the validity and availability of this method is validated by the results obtained by processing real data.

Abstract:By analyzing the DWT's polyphase representation and GPU's general-purpose computation model, this study presents a 2D DWT algorithm based on GPU and polyphase, which combines with modern GPU's multi-texture property and multiple render targets property. The computing form is well suited to GPU's SIMD architecture in the method presented. The number of texture visit is significantly reduced. The GPU's vector processing ability and 2D address accessing ability is well utilized. The experimental result shows that the processing speed is greatly improved.

Abstract:A lower bound on the error rate of linear binary block codes (under maximum likelihood decoding) over BSC channels is proposed. According to the principle of the maximum likelihood (ML) decoding algorithm, the decoding error probability is firstly converted into the joint probability of the error events, and the judge rule of the redundant error events is deduced based on the optimization rule of the improved Dawson-Sankoff bound. Moreover, the calculation expression about lower bound of the error probability solely depends on the Hamming weight enumerator function of the code and the crossover probability of the channel. The simulation results applying to various LDPC codes show that the new lower bound outperforms those generic lower bounds and the sphere packing bound. Its computational complexity is also lower.

Abstract:Aiming at improving the validity of blind dispreading DS-SS signal, the blind spread-spectrum and information sequence estimation of DS-SS signals is studied in this paper. Based on double PN periods, a new method of blinding estimate PN sequence and information sequence jointly was presented. The advantage of the algorithm is that it can estimate the PN sequence and information sequence jointly, with less computational cost. Compared with the traditional methods, this algorithm avoids the problem of phase ambiguity when the whole PN sequences are reconstructed using the two parts of spread-spectrum waveforms, which can highly improve the validity of blind estimation. The simulation results verify the validity of this algorithm.

Abstract:Analysis of how motion characteristics of radar platform influence imaging is the premise of researching on motion compensation, detection, recognition and tracking methods. Aiming at the problem of radar platform motion characteristics and its effect on range profile, the study firstly analyzed the motion characteristics of radar platform, gave an LFM signal model based on motion platform, and quantitatively analyzed the influence on range profile which result from the motion characteristics of the radar platform. It is concluded that, under the condition of general radar platform, the micro-motion of platform influencing the radial velocity/acceleration can be ignored; the translational-motion of platform is the main factor influencing the range profile, the micro-motion of platform have little influence on range profile; radial acceleration influencing the range profile can be ignored. Finally, the simulation results verify the correctness of conclusion.

Abstract:In order to describe the dynamic integration of C⁴ISR system resource and implement decoupling between operational process and military system resource, a service view within C⁴ISR architecture framework based on the research on DoDAF2.0, NATOAFv3.0 and MoDAF1.2 is proposed. Through the formalized description of service view products, this study firstly analyzes the logical relationship between the products within service view. Especially it emphasizes on the formalized description of service interaction process based on OWL-S speciation to adapt to the change of operational process. Furthermore, this paper transforms the evolution description of service interaction process to the change operation of process's ontology description and analyzes the evolution description through the basic and composite change operation finally.

Abstract:Weapon equipment system-of-systems(WESoS) capability planning is an important part of the WESoS research area. Taking the time span and cost of capability planning as the optimization objectives, the multi-objective optimization model of WESoS capability planning is proposed. At the base of WESoS capability spaces description, the method of modeling WESoS capability planning is presented. Genetic algorithm is employed to solve the optimization problem. Then the quantitative method of capability gap analysis is presented as well. The proposed approach provides groundwork in certain degree for quantitative analysis of WESoS capability. Finally, a numerical example is given to illustrate the reasonability of the proposed approach.

Abstract:A deep-seated rough fuzzy C-Means combined (RFCMC) clustering algorithm is proposed. The algorithm alters the distribution of fuzzy membership function by combining the lower approximation and upper approximation. Accordingly, the computation of class centroid and fuzzy membership is modified. Moreover, a self-adaptive adjusting edge parameter algorithm is prepresented. The results from experiments prove the improved effects.

Abstract:Computer simulation is a promising approach to better understand the crowd psychological dynamics. The lack of real data in crowd simulations, however, usually results in heavy dependence on assumptions, and thus hampers the confidence. This research presents the simulation of crowds under confrontation of psychological stimuli, which focuses on the psychological aspect of the crowd and introduces the intervention between two different relationship spaces in the crowd. Firstly, with the agent-based approach, psychometrics is employed in the construction of the individual model to improve the trustworthiness. Secondly, the research describe, by means of the model, the phenomenon that individuals tend to get involved in various relationship spaces, which plays an important role in the procedure of psychological propagation. Finally, a scenario of a crowd in large-scale public activity under terrorist threat is studied, in which the workflow for psychometrics based crowd simulation is demonstrated, and the preliminary results are also discussed.

Abstract:In the analysis of relationship among fire distribution, area division and path planning, the idea of trinity tactical decision of surface ships formation missile path planning (SFMPP) is put forward, and an expandable open simulation architecture is designed based on high level architecture HLA. According to HLA/RTI specification, the federation's FOM/SOM was designed and developed. The event schedule was adopted as the simulation strategy because the system has the characteristic of discrete event simulation, the dynamic model of system was established based on Petri net, and time management and the federates' implementation process were introduced. The simulation demo indicates that the realization of this simulation platform provides anew solution for tactical decision problem of SFMPP.

Abstract:In the clustering analysis of test data of liquid rocket engine, in order to solve the problem that there is insignificant difference between fault sample and normal sample, the maximum scatter difference criterion was introduced and the maximum scatter difference based clustering algorithm (MSD-CA) was presented. In MSD-CA, the similarity of samples was measured by divergence, and the minimizing of the within-class divergence and maximizing of the between-class divergence were processed together. After that, fuzzy theory was introduced to maximum scatter difference criterion, and the maximum scatter difference based fuzzy clustering algorithm (MSD-FCA) was presented and used to do “soft partition” for test data to improve the precision of cluster. The method is verified with experimental results.

Abstract:In order to improve measurement resolution of RLG(Ring laser gyroscope), the mantissa subdivision method was used and its influence on the accuracy of the strapdown inertial navigation system was analyzed. Firstly, the analysis of the traditional four sub-frequency subdivision method shows that its measurement resolution is a quarter period. Secondly, the principle, realization and characteristics of the mantissa subdivision method which is based on four sub-frequency subdivision method were contrastively analyzed. It drew a conclusion that the new method can obviously improve the measurement resolution of RLG. Based on the conclusion above, influences on the accuracy of the strapdown inertial navigation system of the two methods are analyzed by Simulink. The simulation indicates that the mantissa subdivision method can improve the navigation accuracy comparing with the traditional four sub-frequency subdivision method. Therefore, the mantissa subdivision method is meaningful to both theoretic study and engineering applications of high precision navigation system.