Abstract:The dimension reduction method of the true proportional navigation (TPN) guidance law is proposed. Firstly, the rotation principle of the line of sight (LOS) was investigated, two kinds of angular velocities of LOS were presented, and so were their calculation methods. Then, the LOS kinematic equation was advanced, and the new relative dynamic equation between interceptor and target was proposed. It was found that there is an instantaneous rotation plane of LOS (IRPL) in the three dimensional (3D) space, in which two dimensional (2D) guidance laws can be constructed to serve for 3D interception guidance. The spatial 3D true proportional navigation (TPN) guidance law was directly introduced into IRPL without any approximation and linearization to transform into dimension reduced 2D TPN, and the characteristics were studied. Finally, an exoatmospheric interception was taken for simulation to demonstrate the effectiveness of the theory presented in this paper.

Abstract:The enriched finite element method was developed for three dimensional fracture problems in a linear viscoelastic body. To manifest the singularity at the crack tip, the 8 node hexahedral enriched elements and corresponding transition elements were employed, combined with ordinary elements on the zone far away from the crack tip. Three types of elements were used together to form the whole mesh. Based on the boltzmann superposition principle, the incremental constitutive relation for viscoelastic materials was formulated. Furthermore, the incremental formulations of the enriched FEM were derived. The strain energy release rate in a cracked viscoelastic body was obtained through the enriched degree of freedoms. The numerical results show that the present method is accurate and efficient.

Abstract:By applying 5 order accuracy WCNS (Weighted Compact Nonlinear Schemes) to simulate forced oscillation of NACA0012 aerofoil, some techniques of high accuracy method in unsteady simulation were studied, such as inner iteration capability, inner iteration parameters of “dual time stepping” method, and discretization accuracy of time derivatives of Euler equations. The results show that, these coefficients have a remarkable effect on computation accuracy and CPU time when WCNS scheme is applied to unsteady flow simulation.

Abstract:Bank-to-turn (BTT) technology is an important development direction of control technology for hypersonic gliding vehicles. This research focuses on the control system of bank-to-turn for the hypersonic gliding vehicle. By taking the equilibrium gliding trajectory as the reference trajectory, it analyzed the relationship between turn radius, falling height, and bank angle. The analysis shows that when designing the guiding and control command, the flight conditions and the limitation of the control ability need to be considered. Then the dynamics were separated into fast and slow variables in terms of singular perturbation theory. Furthermore, the trajectory linearization control (TLC) method was applied to design the control system. Simulation results show that the controller is robust and the command should be adjusted with the flight conditions to control the vehicle efficiently.

Abstract:Teleoperation rendezvous and docking is referred to as the concept that the chase spacecraft is flown distantly through teleoperation approach. It can be used as a backup for autonomous rendezvous and docking for the unmanned chases during the finally approach stage. The concept of teleoperation rendezvous and docking (RVD) and the previous studies in this field were introduced firstly. Then, a design of the teleoperation RVD system was addressed, which is based on the primary assumed conditions of our future space station project. Finally, a simulation system was developed and corresponding experiments were carried out for verifying the design, especially the design with teleoperation time delay. The results show that the design is feasible, even though there are jobs to be done in the future.

Abstract:Near-space glide vehicle motion was modeled by nonlinear longitudinal dynamic equations. The Inverse system of this model was obtained by using dynamic inversion approach. The relative degree of dynamic model was equal to the rotational motion system order, so rotational motion dynamic model could be Input/Output linearization completely. The dynamic inversion method and optimal control were used in inner-loop and outer-loop for the longitudinal dynamic model. Simulation studies demonstrate that the proposed controller tracks the pitch angle or angle of attack command accurately, meets the performance requirements with acceptable control inputs and is robust with respect to the parametric uncertainties and external disturbance.

Abstract:The aluminum-doped ZnO thin films with ［002］ oriented were prepared using 2-methoxyethan as a solvent system by the sol-gel method. The composition, structure and optical properties were studied by means of Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), Energy-dispersive X-ray microanalysis (EDX) and Spectral shape. The results showed that the ZnO films are hexagonal wurtzite structure, which consists of hexagonal rods growing along C axis. The resistivity of the aluminum-doped ZnO thin films decreases with the increase of the content of Al³⁺.In the visible region, the light transmittance of the ZnO thin films with 3% aluminum is about 90%, and the band gap is about 3.25 eV, which can meet the material requirements for photoelectric devices such as photovoltaic solar cell.

Abstract:Acycloaliphatic(CDR-0122) epoxy resin has good heat-resistance, but it is characterized by being brittle. CDR-0122 modified with different mass fraction of epoxy (E-51) were studied. First, DSC analysis was carried out to determine the activation energy, reaction order and the best curing procedure of the modified resin. Then mechanical property and heat-resistance property of the cured modified resin were tested. The results showed that, compared with the unmodified CDR-0122, the activation energy of the modified resin system decreased slightly, and its tensile strength and flexural strength increased by 52.38% and 54.77%, respectively, but the glass transition temperature decreased slightly. Considering all aspects of performance, the system of CDR-0122 modified with 30 wt% E-51 is the best one.

Abstract:The stress intensity factor of a center embedded elliptical crack in non-uniform stress fields, which is along the thickness direction of the plate, is gained based on the linear line-spring model for embedded cracks. The two dimensional weight function is used to transform the non-uniform stress field to an equivalent uniform one. The singular integral equations are formulated and the numerical results in four cases of stress distributions are gained by Gauss-Chebyshev method. The results are in good accordance with those given in the previous literature when a0/c0＜0.4、a0/h≤0.3, and the rationality and reliability of this method are demonstrated.

Abstract:In the single-axis rotation inertial navigation system with ring laser gyroscope (RLG), the single axis rotation can compensate the vertical errors of the inertial apparatus automatically, but cannot compensate the axial vertical errors, so the precision of the system is determined by the drift of the axial RLG. A novel identification method based on radial basis function network is proposed for the axial RLG drift. The inputs of the network are the latitude error and change of the temperature, and the network is trained for steady and non steady state, in which the identification capability is less than 0.0003°/h. The experiments show that this method can estimate the axial RLG drift efficaciously, and the result of the navigation is excellent and can meet the practical demand.

Abstract:In order to achieve automatic discovery of simulation resources in a SAC( Sharing Among Clouds) simulation environment, resource request description method and discovery algorithm were studied, and scenario driven resource discovery method was proposed. By using extended MSDL (Military Scenario Definition Language) as resource request scheme and DM&TF (Double Mapping and Triple Filtering) as resource discovery algorithm, resources for cloud simulation can be automatically discovered. Analysis showed scenario driven resource discovery method was able to automatically discover large numbers of resources needed for a simulation in pragmatic level, which is of great help for rapid configuration of simulation environment.

Abstract:Aiming at evaluation and selection of maintainability design schemes, a new preferred selection method based on integrative evaluation of design factors was proposed. Considering the uncertainty and fuzziness of design factors’ evaluation, linguistic assessment values of maintainability design factors were quantified on the basis of the set pair analysis theory, and evaluation and decision-making model was established by introducing the weighting method based on AHP into similarity scale of schemes. Finally, preferred selection for design schemes of some manned spacecraft power system was taken as an example to illustrate the application and effectiveness of this method. 

Abstract:The development of Course of Action(COA) is a key step of military planning. In most existing literature on COA development, the previous studies only take unilateral actions of friendly force into account. Considering the antagonism of war, we propose models that contain actions of both friendly and enemy force based on multi-stage games with incomplete information. Influence net is used to analyze the uncertain relationships between actions and battlefield situation. In the end, numerical examples are presented to illustrate the models and solution, showing that the COA developed in the current study is suitable for the antagonistic situation.

Abstract:For a repairable system consisting of multiple equipments of the same type, spare demand and its supply plan will affect the number of workable equipments, and hence exerts effects on the demand of other spares for the equipment. Therefore, the assumption that the spare demands are mutually independent and have no relation with the spare supply plan of the system is not correct. This study considers the correlated demands as well as the effects of the spare supply plan on the spare demand, and describes the spare demand law by the Markov process. Availability calculus methods are presented according to the two cases of cannibalization and non-cannibalization respectively. Based on the methods, a spare optimal allocation model is constructed by setting spare allocation cost as the optimization target and system availability as the constraints. The model is solved by marginal analysis. Finally, a case study is presented to illustrate the validity of the proposed model.

Abstract:Expert’s opinion consensus is one of key problems in the War Design Engineering. Firstly, the characteristics of experts thought, such as adaptive, cluster and non-linear, are analyzed from the view of complex theory. According to their interactive relationship, experts are divided in to two categories, and the convergence process is modeled by Markov transmission matrix. Then, the necessary and sufficient conditions of reaching consensus for each category experts are presented and proved. It ends with the conclusion that the condition of experts thought convergence is not only relative to interactive relationship matrix, but also the primal opinion of expert. Finally, some propositions are verified by computer simulation.

Abstract:An algorithm of monocular camera/SINS integrated navigation is presented for structural road. In order to overcome the difficulties of point features matching and tracking, which are restricted by carrier velocity and camera view, line features are extracted from the lane marks on the road. The line features are represented by dual quaternion. Compared with the relative pose estimation algorithm based on dual quaternion, the proposed algorithm deduced the formula of image feature increment and camera position increment. After registration and time synchronization, the velocity computation difference between the SINS and the camera was chosen as observation of integrated navigation. A Kalman filter was used to correct the integrated navigation error including the camera scale factor error of velocity measurement. The experiment results show that the proposed algorithm is accurate for structural road.

Abstract:This paper presents an experimental method to measure surface temperature field distribution of airplane under solar radiation by airplane downsizing model, and suggests a method to realize analogue display of 3 dimensions for temperature field distribution by finite element method. This method may avoid the influence of the uncontrollable intensity of natural solar radiation and the variable ambient temperature under field measuring condition, and provide an efficient method to validate the theoretical model of surface temperature field distribution of airplane under solar radiation and to measure it by experiment. It will be beneficial to the research of infrared characteristics and calendar life for airplane.

Abstract:The method of finding an optimal aircraft trajectory to minimize the probability of detection by opponent radar detection systems is proposed. RCS data model, a three dimension (3D) aircraft and detection model, was established first. And then, the problem was described as an optimal control problem. The constraint functions were constructed by attitude control, trajectory constraints and boundary conditions. The cost function was formed to minimize both the probability of detection and the total flight time. After that, the continuous optimal control problem was parameterized to discrete nonlinear programming problem by Gauss pseudospectral method (GPM). Simulation results demonstrate the feasibility of the proposed method in low observable three dimension trajectory optimization problem with monostatic radar and bistatic radar system, and it is also shown that the probability of detection and the exposure time decrease significantly.

Abstract:An analytical method of calculating the normal and tangential forces in linear synchronous motor with air-core and Halbach permanent magnets is developed. First, the analytical solution to the normal and tangential forces of the rotary motor with the same structure is deduced. Then, the proposed method is extended to linear motor, and the analytical method of computing the normal and tangential forces in linear synchronous motor with air-core and Halbach permanent magnets is obtained. Finally, the effectiveness of the proposed analytical method is validated by Ansoft Maxwell, which is a famous finite element analytical software. The proposed solution provides an important tool for structure design and performance analysis of linear synchronous motor with air-core and Halbach permanent magnets.

Abstract:To meet the high memory bandwidth of SDR-oriented SIMD DSPs, a novel Vector Memory(VM) architecture is proposed. The VM consists of 16-way Vector Memory Blocks(VBs), and each VB contains two groups of multi-bank memory structure with low-order interleaved addressing. This structure aims at reducing the memory access conflicts, making best use of the bandwidth of the multi-bank memory, and realizing the parallel vector data access at the cost of low power consumption. Besides, a vector rearrangement unit is designed and implemented in the VM to support the 16-way unaligned SIMD vector access and share the VM space. Experimental results show that the proposed VM architecture can efficiently reduce or eliminate the data shuffling operations and speed up SDR applications.

Abstract:Nowadays, organization faces the problem of acquiring correct information from data asset to support decision-making. To solve this problem, a semantic correctness oriented relational data access method, namely SCORDA, is proposed. Firstly, ontology was used to describe the concept view, which is used in data access task, and description logic makes a suitable tradeoff between expressiveness and complexity. Secondly, a LAV+GAV mapping formalism was adopted to solve the schema heterogeneity and impedance mismatch problem. Furthermore, a special structure named dynamic ABox is provided to deal with the instance checking problem, and to ensure the semantic correctness of answers based on the model theory semantic of ontology. Finally, the feasibility of SCORDA method, through implementing a prototype system， was validated.

Abstract:As a model-based vulnerability analysis technology, attack graphs can identify network vulnerabilities and their interactions; they can also reveal all possible attack paths and potential threats. Based on the attack graphs, alert correlation graphs are proposed in the paper. An alert correlation graph maps real-time IDS alerts into attack paths using prior knowledge encoded in attack graph, and reveals attack progresses and attackers’ intention dynamically. A novel quantitative network vulnerability assessment method is presented based on the alert correlation graph, which analyzes network vulnerabilities by dynamically computing the weight of alert correlation edges. The research also demonstrates, by examples, that the proposed method combines static prior knowledge about network vulnerabilities with dynamic attackers’ intentions, and reveals the change of network vulnerability under real-time attacks.

Abstract:Aiming at the complex background suppression problem, a two-prediction-architecture fused complex IR images background suppression algorithm is proposed. In the local region of each pixel, the Nucleus Similarity Degree(NSD) is computed on the basis of the gray value similarity and spatial distribution correlation. Then, the outputs of two spatial filters with different structures are fused as the final background prediction result. Finally, the suppression is done by subtracting the prediction from the original image. The experimental result demonstrates that the proposed algorithm can get better performance in different complex IR images while the structure of the algorithm is simple, and it is suitable for engineering application.

Abstract:For a single-polarization-truncated-cone-phased array antenna stimulated by horizontal or vertical polarized dipoles, the spatial polarization characteristics are modeled when the array antenna electronically scans in space. The theoretical analysis and simulations show that: the spatial polarization ratio of a single-polarization-truncated-cone-phased array monotonically increases as the angles between the pointing angles or observation angles and the normal increases; the spatial polarization ratio monotonically decreases as the slope angles decrease; the patterns of a single-polarization-truncated-cone-phased array are related to the polarization of array elements, the pointing angles, and the observation angles; the larger the size of a single-polarization-truncated-cone-phased array antenna is, the more abundant the spatial polarization information is. These conclusions offer a theoretical foundation for studies such as the polarization scattering matrix measurement, the polarization filtering, and the polarimetric anti-jamming based on the spatial polarization characteristics of the single- polarization-truncated-cone-phased array. The conclusions offer a theoretical basis for the studies such as the antenna design, the polarization characteristics analysis and the polarization calibration of the full-polarization-truncated-cone array as well.

Abstract:In the three-dimensional reconstruction of urban areas and man-made infrastructure, the urgent problem of SAR tomography is how to achieve satisfactory elevation resolution with a small number of non-uniform passes and preserve azimuth-range resolution simultaneously. An imaging method for SAR tomography based on RELAX algorithm is proposed in the framework of deterministic models. Compared with the spatial spectral estimation method that works statistically, this method does not need to deal with a spatial multilooking and maintains high resolution of direction dimension-distance dimension. Compared with the singular value decomposition method, this method has much better resolution of elevation dimension. Results obtained by processing simulated data and real data of ENVISAT-ASAR verified the promising potentiality of this imaging method.

Abstract:A novel method for high resolution direction-of-arrival (DOA) estimation is proposed. The novel approach constructs the spatial spectrum by utilizing the steady-state weights of the adaptive algorithm in direct data domain instead of the noise subspace. The proposed method can solve the false peak problem effectively in the spectral peak search. The noise subspace can be closed with several groups of linear non-correlated steady-state weights from utilizing different reference signals. A practical method for the DOA estimation of correlated signals is also presented, which utilizes the symmetric conjugate vector in direct data domain. Compared with the conventional method, the proposed approach does not need to estimate the source number and the covariance matrix. As it does not need the eigendecomposition and only has a computational complexity of O(MP), it is a practical method for DOA estimation of correlated signals.

Abstract:To amplify the DC signal is a discommodious issue, because of the on-chip DC signal has such properties as little swing, less coherence and likeliness to be interfered. In light of this, a “voltage-frequency-voltage” mode DC signal amplifier is proposed, in which the frequency is the carrier signal. This amplifier is highly linear, and is equipped with a high linearity “voltage-frequency” modulator and a “frequency-voltage” de-modulator. The simulation experimental results show that the DC signal amplifier amplifies the input voltage signal efficiently while achieving stable high linearity, and the DC gain is 2.4.

Abstract:A cooperative orthogonal frequency division multiplexing (OFDM) system with a source and a non-regenerative relay transmitting according to Alamouti’s STBC is considered. The capacity of the system is analyzed and the analytical expression is presented. To improve the capacity of the individual power constrained system, a power allocation algorithm named as the Stepwise Iterative Power Allocation Algorithm (SIPAA) is proposed. The basic principle of SIPAA is that the water filling power allocation is implemented stepwise for both the source and the relay within iterations. To reduce the complexity of SIPAA, the object function is linearly processed before the water-filling power allocation, and the power vector is also linearly processed after the water-filling power allocation. It is confirmed by the simulation results that a significant system capacity improvement can be achieved by the proposed algorithm, compared with conventional equal power allocation algorithm. Moreover, the power allocation can be completed within a few iterations.

Abstract:To promote the execution efficiency of HLA system which executes on high performance computing (HPC) platform, a self-adaptive communication mechanism, named SACM, is proposed for the hierarchy communication environment of HPC. By this mechanism, the connection with lowest latency can be established from the network information of computing nodes. The shared memory, high speed IB network and Ethernet network can be selected by federates adaptively. Aiming at the demand of shared memory communication between federates within one node, a high speed shared memory communication algorithm based on distributed infrastructure is proposed, and the communication performance can be improved by this algorithm. Experiment result of object attributes value updating latency has shown that the communication performance of RTI executing on HPC platform has been greatly improved.

Abstract:Bio-inspired array is a new type of circuit based on the self-healing mechanism of organism. The current study presents a novel prokaryotic cell based bio-inspired array structure based on the gene structure of eukaryotic cell and prokaryotic cell. Simulation experiment on designing a self-healing DBPSK circuit is carried out and the result shows that the presented prokaryotic cell-based bio-inspired array structure is effective and consumes less memory storage than the traditional eukaryotic array structure.

Abstract:The beam output of deformed Spaceborne SAR antenna array and the deformation error compensation are studied. Considering the flexible antenna array which may be adopted in the future Spaceborne SAR, a closed loop system for measuring and controlling of Spaceborne SAR antenna array’s deformation is proposed, and the steering vector model of deformed antenna array is presented. It was found that the mild deformation affect the beam’s sidelobe output more than the beam’s main-lobe. Then, the compensated weights were solved by the least square method, which can approximate the deformed antenna array outputs to the original antenna array outputs at most. Next, the deformed antenna array measuring precise demand was worked out. The validity of this method is verified by simulation.

Abstract:The conventional line-of-sight (LOS) geo-location method using two-dimension interferometer on a satellite leads to heavy payloads and it is always under the effect of amplitude phase inconsistencies among receiving channels. A novel passive localization method is proposed, which merely needs two receiving channels to form a one-dimension interferometer on a spin-stabilized satellite. Rate of phase difference change was measured for emitter localization. A location algorithm based on particle swarm optimization (PSO) was designed. The impact of rotating speed and rotating plane of the interferometer on localization precision was analyzed. The results showed that localization precision can be improved by increasing rotating speed of the interferometer, the rotating plane should be perpendicular to the satellite position vector at the initial moment in order to get good localization precision in all directions around satellite projection point on the ground, and localization precision of the proposed algorithm can approach the Cramer-Rao lower bound (CRLB).