Abstract:The sound velocity of the materials at sufficiently high pressure is an important quantity reflecting material qualities under extreme conditions. In this paper, from the shock adiabatics and the Gruneisen equation of state, an isentropic, which corresponds to shock adiabatics, is delivered, and the formulas of calculating sound velocity along isentropic and isothermal compression, as well as the Hugoniot curves, are presented. The Hugoniot sound velocities of aluminum and tungsten are calculated. The calculated results are in good accord with the experimental results.

Abstract:The model of bi-reaction region of hydroreactive metal fuel is presented. In consideration of chemical reaction process, the thermodynamics character of hydroreactive mental fuel is analyzed. The influence of prescription and other factors on motor performance are investigated preliminarily.

Abstract:In order to meet the requirements of the ground test control of gas generators, We analyze the control behavior, and puts forward an advanced object-oriented flexible control model (OOFCM) for ground test of gas generators, which accords with the developing direction of the measurement and test technology. Based on the OOFCM, a flexible control system (FCS) is realized, which can meet the requirements of the ground test control of all kinds of gas generators. The FCS has been used in the test successfully. Compared with the older test control system, the new system has higher dependability, simpler structure and more flexible manipulation.

Abstract:A numerical method is developed to simulate the unsteady flows involving moving boundaries. For this method, dynamic unstructured grid technique was used, and a MUSCL type finite volume scheme was constructed to discretize the 3D unsteady Euler equations described in ALE frame. The deformation of unstructured grid was implemented by spring analogy. The whole methodology was then applied to simulate the unsteady transonic flow of the three-dimensional rigid wing undergoing a forced sinusoidal motion in angle of attack. Computational results are in agreement with the experimental data, and the nonlinear flow characteristics caused by the fluid and structure interaction was clearly obtained. It can be concluded from the research that the whole methodology presented here is adequately accurate and reliable, and can be applied in aeroelasticity study and a series of fluid and structure interaction problems.

Abstract:To study the compatibility of polymers and liquid oxygen, four types of epoxy resins with different chemical structures were selected, and then were copolymerized with cyanate ester. Thermal analysis was conducted on the cured compounds for oxidation weight gains analysis, oxidation decomposition weight losses analysis, flash points, etc. Then the compatibility of the cured compounds with liquid oxygen was contrasted with liquid oxygen impact sensitivity. The oxidation and combustion properties of the cured compounds are consistent with their compatibility with liquid oxygen. Polymers with better anti-oxidation show better compatibility with liquid oxygen. This conclusion helps us see deeper into polymers' compatibility with liquid oxygen, instructs us to select or design polymers compatible with liquid oxygen. Furthermore, besides the liquid oxygen impact test, thermal analysis can play an important role in charactering polymers' compatibility with liquid oxygen.

Abstract:Ni-Zn ferrite powder with different composition were prepared by Sol-gel process using Fe(NO₃)3·9H₂O, Ni(NO₃)2·6H₂O, Zn(NO₃)2·6H₂O, citrate acid and ammonia as raw materials. The thermal decomposition behavior of dried gel and crystallite size of synthesized powders were studied by using TG-DTA and XRD. Moreover, the relationship of ferrite composition on electromagnetic properties were investigated by network analyzer. The results reveal that the imaginary part of permeability of synthesized powders decreases with frequency and the content of Zn in the Ni-Zn ferrite powder.

Abstract:The condensation method for the analysis of viscoelastic interface crack with similar shape element is put forward. By this method, similar shape elements are generated near the crack tip, forming a substructure with a large number of similar shape elements. And then the large number of freedom degrees in substructure is condensed out. Identity of stiffness matrix between the similar shape elements is used fully during the process of condensation, The tension of bi-viscoelastic and elastic-viscoelastic material rectangle plate with the single edge crack is solved to illustrate the use of this method.

Abstract:Partially sintered zirconia ceramics (PSZC) were prepared via isostatic pressing and partially sintering，with zirconia nanopowder as the raw materials. PMMA-Zirconia organic-inorganic composites were prepared by vacuum infiltration of the prepolymerized MMA into the PSZC, followed by in-situ polymerization. The results show that prepolymerized MMA immerged fully into the open pore of PSZC and polymerized. When the relative density of PSZC is within the range of 63%～82%, the composites have a three-point bending strength of 154～287MPa, fracture toughness of 3.68～4.81MPa·m^1/2 ,which are much higher than those of PSZC. The composites can be machined by dental CAD/CAM system to manufacture dental restoration.

Abstract:A novel power conditioning circuit for flux compression generators (FCG) to drive high impedance loads is presented. FCG usually has very low impedance, and power conditioning is necessary with high impedance loads. The traditional power conditioning scheme uses a pulse transformer and sometimes an additional capacitive pulse forming line (PFL) to improve the output waveform, making the system bulky. The paper introduces a circuit without transformers, using PFL as an inductive energy storage unit. This scheme has the advantages of simplicity, compactness, and easy insulation. Numerical simulation is shown to prove the concept. By using this circuit FCG will have wider applications.

Abstract:The contact algorithm based on Riemann solution was used to simulate the penetration process of high velocity impact problems in two-dimension axisymmetric coordinates. The artificial viscosity hadn't been used when the velocities and stresses at the contact surface were determined by Riemann solution instead of the mean values of velocities and stresses between the contacting basic and surrounding particles. It shows the achieved result is the same as FEM, and the method can be applied in impact problems.

Abstract:An eigen matrix method is introduced to obtain the properties of one-dimensional metallodielectric photonic crystals.The results show that this crystals have the spectra of being transparent in the visible range, highly reflecting the ultraviolet light and microwaves ,and an even wider omni-directional band gap in which the reflection is higher than the dielectric photonic crystals.

Abstract:With the advances in image-guided weapons, it is quite necessary to develop a real-time digital scene simulator system that can test in laboratory the guiding information processing machine. A real-time digital scene simulator system, composed of a high performance PC machine and a PCI card, is introduced in this paper. Especially, the work flow and structure of the simulator system, together with the principles and implementing methods of the system software and hardware, are described in detail. Finally, the experimental results indicate that the system can meet the requirements of practical applications.

Abstract:Aiming at the signal form and the gererating method of the deceptive scene jamming for spaceborne SAR system. This paper proposes the method of jamming based on bistatic location. This method first uses bistatic passive detectors to locate the jammed radar, then smoothes the track and produces jamming signal. It provides accurate position info of the jammed radar, eliminates the effect of random location error on imaging. The bound of location error and its effect on jamming result are studied, so the important problem in implementation of the deceptive scene jamming technique is resolved. The simulation result shows that this method can provide effective jamming.

Abstract:The paper deals with the effects of the angle random walk and engine jamming on SINS alignment. An algorithm is proposed which is based on the interval wavelet transform and forward linear prediction. The algorithm uses forward linear prediction and the ability of the interval wavelet transform to restrain terrible edge effects, thus, the angle walk and engine jamming are reduced effectively. The results prove the feasibility of the method.

Abstract:FPGA-based implementation of LMS algorithm is one of the key techniques in the application of adaptive array antennas. This paper proposes a method for implementing the fixed-point LMS algorithm based on FPGA . On the premise of satisfying the real-time quality of the system, it's comparatively easy to implement the method, and the precision and dynamic range of the algorithm can be ensured definitely. Finally, the simulation results show that this method is feasible.

Abstract:The problem of LFM pulsed radar's ranging bias due to the range-Doppler coupling is studied. The mechanism of the ranging bias is derived and analyzed. The nolinear residue of the bias neglected by most researchers is pointed out emphatically. And the relationship between this residue and the parameters of the radar waveforms and target motion is analyzed. An unconstrained optimization algorithms is proposed for the estimation of the bias residue. At last, experimental results prove the analytic conclusion and estimation algorithm are correct.

Abstract:The threshold group signature is a generalization of group signature, in which only authorized subset can represent the group to generate signature and the identities of signers of a signature can be opened in case of later dispute. We point out the redundancy of a dynamic threshold group signature scheme and demonstrate three attacks on it. The security analysis indicates that the scheme is not secure against framing attack and cannot resist conspiratorial attack and the threshold value cannot be renewed safely.

Abstract:The simulation grid is a distributed simulation platform built through grid technology. On the platform the distributed simulation applications can be executed by utilizing the powerful sharing resource. The research of the simulation grid prototype system is the basis of solving the key technology to build simulation grid. SGE is a tool to construct the local and cluster grids. This paper presents a recent research of building SGE-based distributed simulation grid prototype system. Specifically, its framework provides the dual channels of communication. One channel takes charge of communicating among components of the grid, and the other one takes among HLA federates. In particular, the grid supports three modes of HLA scheduling tasks, which are differentiated according to (1) processes, (2) federates and (3) federations. Results of this study demonstrate the technical feasibility of constructing SGE-based simulation grid, and simply build the prototype system to test the performance of three scheduling task modes.

Abstract:Radar association is a key issue of the electronic counter system now because it can reduce the false and repeat the radar. We present a new radar association method which combines the laws of the occurence of the radar signal and the distribution of the radar feature parameter. The method can recognize all kinds of radar radiating source quickly and accurately. The results of test indicate that the method is effective.

Abstract:The formation configuration design of the distributed spaceborne interferometric SAR (DSInSAR) is the key issue of the system design. The system performance optimization and formation flying orbit dynamic characteristic are its two basic restrictions. The DSInSAR has the characteristic of bistatic, squint and spatial baseline. As an example, a master transmitter satellite and multi receiver satellite system is analysized. The relation of height-measure accuracy and baseline vector is established. The relation between the differences of the two satellite orbit roots and baseline vector is set up too. So the baseline vector can be expressed by root difference. A formation designing rule that optimal height-measure accuracy can be acquired in the middle time of the system working is presented. Base on this rule, a design method of the two satellite and multi-satellite formation is presented. Simulation shows that the height-measure accuracy value of the optimal formation configuration is prior to that of interferometric cartwheel and pendulum.

Abstract:The direct algorithm of interferometric synthetic aperture radar measuring is to directly introduce the absolute phase difference into range equation and Doppler equation to resolve the ground coordinates. By using the ideal image coordinate, absolute phase difference and orbital position of InSAR which include reasonable errors as the initial data, we can get the ground coordinates which include the errors and realize the analysis of geometric accuracy of the ground coordinates. In order to introduce the errors of the baseline length and attitude into orbital position, we propose the corresponding mathematical model. The computation results show that the accuracy of direct algorithm is almost the same as that of the classical algorithm.

Abstract:The propelling modes utilizing the long-fin undulations are considered having great potential for exploiting the future underwater vehicles. The biological background and mathematical analysic methods of the underwater biomimetic propulsor employing the long-undulating-fin are presented. The achievements and the current situation of the researches on the underwater long-undulating-fin propulsor at home and abroad are generally summarized. The control problems which must be solved by the underwater biomimetic propulsor are tersely discussed. The challenges faced by the propulsive system control are state keeping under serious perturbations, rapid maneuvering, power-efficient endurance swimming, and trajectory planning and tracking. The design and control of the underwater biomimetic propulsors taking up these challenges will require state-of-the-art engineering and biology.

Abstract:In the area of maglev train system research, the suspension controllers are substituted by spring-dampers for the sake of simplification in a lot of documents. However the validity of this method and the reliability of the results have not been further analyzed. This paper analyzes the essential difference between the spring-damper and controller through the mathematical model, discusses its influence on the system performance from three factors: stability, dynamic responding characteristics and high frequency response. Based on the mid-test train of the National University of Defense Technology, a simulation is done to validate the difference between the spring-damper and controller. In conclusion，the paper demonstrates the substitution is nonequivalent.

Abstract:The problem of levitation control system's restriction on the grade ability of EMS Maglev is analyzed. Firstly, based on the transform functions of the system and controller models, the relation between the grade climbing ability and frequency band and damp are corresponded by regulating the single-real pole to non-dominant pole. Secondly, the relation between the maximum tracking error and the moving velocity is analyzed based on the example of the circular transition curve. Finally, comparing the tolerable error, the relation between the minimum curve radius and the maximum climbing velocity is tabled at the end , which is significant to engineering.

Abstract:The mechanical properties on the active surfaces of the molds or dies will be directly influenced by non-uniform distribution of the geometric intrinsic quantities such as curvature, metric invariant, and convexity-concavity of the surfaces. This paper shows an investigation made on the relationship between such geometric intrinsic quantities and the mechanical quantities. The results demonstrate that discontinuity of Gaussian curvature will lead to discontinuity of deformation and frictional dissipative energy. The frictional dissipative energy will increase with the decrease of the normal curvature on the deep-drawing path. The heat flux will increase with the increase of inflection points on the surface. These provide novel references for optimal design of the molds and dies.

Abstract:Target assigning is an important problem for autonomous control and management of cooperative UAVs. To resolve targets assigning and formation configuration for cooperative autonomous UAVs, a satisficing-decision-based targets assigning method is proposed. Satisficing-set computing, joint satisficing function, joint selectability function, joint rejectability function, which are key elements of the method, are mainly discussed. Then the satisficing-decision-based targets assigning algorithm is simulated against the background of suppressing the enemy's antiaircraft.The experimental results show that the method can efficiently and quickly resolve the target assigning for cooperative autonomous. The method gains much decision time with little degradation of target assigning solution performance.

Abstract:The determination of weight vectors is the key problem for multiple attribute decision making. The linear combination weighting is an effective way to do it. The general description of the linear combination weighting problem is provided. Based on the information used to solve the problem, the solution methods are classified as four different classes. The fundamental idea for each class is demonstrated. The characteristics of each class are analyzed. This is useful to understand the different methods, and can provide references to the practical use of the methods.