Abstract:By analyzing the working characteristics of the liquid rocket engine, strategies of applying data mining from the point of view of the data warehouse for FDD of LRE are proposed. The data mining methods possibly applicable to different topics in the fault detection and diagnosis of LRE are compared. Primary research results show that such data mining methods as clustering, classification, association, time-series analysis and outlier analysis are feasible in the FDD of LRE.

Abstract:The information preservation method (IP) is applied to calculate the low-speed flow in a tube. The results are compared with that of the experiment and the datum tallies well. The results of IP method is better than NS equations'. The study indicates that IP method is an effective method to simulate the low-speed flow in a tube. Furthermore, better results and higher computer efficiency can be achieved.

Abstract:The temperature distribution of the cylindrical shell irradiated by mobile laser beam is studied. Based on the method of Fourier series expansions, an analytical solution of the temperature field is deduced for the thin cylindrical shell, irradiated by intensive laser beam in four different motion modes，and programs are coded for computation. Numerical simulation results of this method are identical with those of finite element method. Finally, we analyze the effect of the rotating angular velocity and moving velocity on its temperature field under laser irradiation. The conclusion is drawn that temperature rise is most prominent in the case of periodic irradiation. Numerical results provide evidence for the laser resistant radiation of missiles in theory.

Abstract:Crack-free homogeneous nanoporous silica films on silicon wafers has been synthesized via a supercritical drying of wet gel films that were obtained by spinning coating the polymeric silica sol using acid/base two step sol-gel method with tetraethoxysilane(TEOS) as precursor. The nanoporous film is amorphous and three-dimensioned network, cross-linked by the primary particles which sizes distributed between 30～40nm showed by XRD and AFM. The thickness and refractive index of the silica films were measured by spectroscopic ellipsometry. The silica films' thickness is 300～1100nm, refractive index is 1.13～1.23, porosity is 50%～70% and dielectric constant is 1.9～2.4. The silica films' thickness increases as the solvent isopropanol (IPA) amount reduced, catalyst NH₄OH amount increased, SiO₂ sol viscosity increased and spin speed reduced. The films' dielectric constant loweres as NH₄OH amount and SiO₂ sol viscosity increases while IPA amount and spinning speed has little effect on the films' dielectric constant.

Abstract:Silicon carbide fiber reinforced siliconoxycarbide (SiC_f/Si-O-C) ceramic composites were fabricated via precursor infiltration and pyrolysis using polysiloxane. The effects of the inert fillers (IF) SiC, SiO₂and SiO₂cenosphere on flexural strength, density, coefficient of heat conductivity of SiC_f/Si-O-C composites were studied. Microstructure analysis shows that the properties are mainly influenced by the inner fillers due to the interface structure and the relative density.

Abstract:Based on a 3rd order weighted NND scheme, a dual-time stepping method is used to solve the 2D unsteady Euler equations and the flow field of a forced vibration airfoil at transonic speed is simulated numerically. The influence of the inner iteration steps, the inner iteration tolerance and the magnitude of physical time step on the calculation results and efficiency are discussed. The results achieved with the present methodal are compared with the experimental results.

Abstract:TbDyFe transducer with polarization maintaining fiber (PMF) is produced. An all polarization maintaining fiber M-Z interferometer is set up. Magnetic field sensing is realized with optical fiber by means of work point controlling method. This system has many advantages such as simple construction and anti-jamming. Especially it has solved the polarization instability. Responses of the system with the change of the DC signal and AC signal amplitude are measured. The smallest AC magnetic field 3×10^-10T is obtained in this system.

Abstract:An accurate measurement algorithm of Doppler frequency rate between the clusters of pulses is given. The algorithm uses cross-correlating function between the succeeding pulse in the cluster to estimate ambiguous frequency of the cluster and select the same ambiguous frequency between the succeeding cluster of pulses to solve ambiguity to acquire the relative frequencies. Because these relative frequencies include the same ambiguity, the filter algorithm can be used to estimate the Doppler frequency rate between the clusters of pulses. The relative frequency and Doppler frequency rate estimation accuracy is high, and the process of solving the ambiguity is simple. The performance of the algorithm is effectively demonstrated by the computer simulation and ground test.

Abstract:In order to enhance the safety of liquid rocket engine (LRE) turbopump and minimize the damage of its faults, a health monitoring system of turbopump (TP-HMS) is designed for a large LRE. After the realization of the subsystems for signal acquisition, real-time fault detection, post test data analysis and real-time database support, the function and the flow of execution are investigated and analyzed. Then, the multi-feature adaptive threshold compositive decision-making algorithm (MATA) is validated with the historical data from LRE test as well as real-time data from rotor test platform. To obtain the information of fault signals, the adaptive spectrogram is applied in the data analysis. It is shown that MATA can detect the faults in real time and give no false alarm in this case. Through the application of adaptive spectrogram, the cross-term interference is suppressed. The time frequency information is obtained accurately. Therefore, the conclusion is drawn that the TP-HMS design is suitable for the health monitoring of LRE turbopump.

Abstract:In order to stabilize the output video of camera system in good time, a real-time electronic image stabilizing algorithm based on feature matching is presented. The improved Kanade-Lucas-Tomasi (KLT) algorithm is applied to feature extracting, and a new feature matching algorithm based on projection mean is put forward. Considering the reliability of stabilizing results, a feature validation test method is also given. Besides, based on the high real-time demand for motion filtering, the recursive Kalman filtering is applied in intentional motion parameter estimation. As experiments show, the algorithm just takes 24.7ms to stabilize a single image on PC, fast enough to satisfy the real-time demand, and it has good stabilizing results.

Abstract:A new way related to the performance analysis of Surveillance and Reconnaissance Systems is proposed to evaluate the situation awareness. At first, NIIRS and GIQE are used to find the relationship between the remote images and targets' detection probability, so the probability distribution of the targets in the surveillance area is gotten. Secondly, considering the real distribution of the targets as the users' need for information, we use Kullback-Leibler distance in the information theory to measure the difference between the probability distribution of the targets and the users' need for information. Finally, a situation awareness curve of different S&R systems is derived and the impact analysis of the transmission and processing delay on the curve follows.

Abstract:A novel biparametric OS-CFAR(BOS-CFAR) detection method for AEW radar in the sea clutter is proposed.The performance is discussed and analyzed for multiple-pulse noncoherent integration when this method operates in the multiple-target environment in the non-Gaussian sea clutter background. Theoretical analysis and simulation result show that the proposed method can enhance the CFAR detection performance for AEW radar in the sea clutter background effectively.

Abstract:The dynamic characteristics of the gap sensor necessary for suspensive control system in maglev vehicle, are difficult to measure at high frequency by mechanical methods. The eddy current effect of the measured conductor is replaced by the simulative eddy current field. The measurement method of dynamic response based on modem is presented and discussed with sinusoidal signal and impulse adopted. The result of relevant experiments is given. Compared with the mechanical methods, the proposed method is proved to be more effective.

Abstract:The new requirement of modern war on the range of radio fuze is analyzed. A new high range frequency agile radio fuze scheme is proposed, and the ideals of software radio is also adopted in design, which make fuze possess the ability of software programmable and enhance the ability of anti-jamming. An algorithm of range based on multi-frequency pulse comparing phase is proposed based on multi work-frequency agile, which gains information of range using phase differences between echoes. The simulations verify the feasibility of this kind of high range frequency agile fuze.

Abstract:Most of the existing methods of high resolution direction estimation rely on the assumption that the signals are from point sources. Thus, the application of the conventional estimation methods to the distributed sources will show grave deterioration in performance. A new model is constructed for the distributed sources, and an estimation method named DIS-MUSIC proposed. The performance of this method is analyzed and computer simulation results show that DIS-MUSIC is of much better performance than MUSIC algorithm.

Abstract:Based on the radar image model of spaceborne parasitic SAR system, interferometric model of this new system is proposed; new characters and limits are analyzed in detail. The concepts of the range and azimuth effective baseline are given at the same time. The limits of effective baselines and performance of INSAR relative height measurement of Cartwheel and Pendulum configuration are analyzed. The influence of interrelation of the range and azimuth baseline and pre-filtering technology are pointed out.

Abstract:Using the virtual instrumental technology of adopting the soft ware of LabView, and utilizing the multithreading technique, we construct the auto-measurement system for the antenna and RCS based on the instrument and the rotation platform working harmoniously. The design makes the instrument more functional, and improves the automation and efficiency of the fest.

Abstract:Effective data source selection strategy is one of the important issues of the spatial information retrieval. This paper proposes a method to select data source based on spatial scale semantics. The method determines the data source set for the distributed query plan fully considering the human vision features, filters those data sources which don't contribute to the final result. Through prefetching the simplified representation of data sources, the method can further reduce the overall cost of a query. The experiment shows that the proposed method has favorable performance both in small and large size query.

Abstract:A new texture feature extraction method using Local Walsh Transform (LWT) is presented. The definition of LWT is given. The statistical properties of LWT coefficients are analyzed. The texture discrimination performance of the moments of LWT coefficients are investigated. Detail examinations reveal that the LWT coefficients of the natural texture images usually do not yield to Gauss distribution, their even-order moments have high texture discrimination performance, while their odd-order moments have low texture discrimination performance. Hence, the even-order (2^nd, 4^th, 6^th order) moments of the LWT coefficients are selected as texture features. Compared with the other texture features defined by Haralick^［1］,Wang and He^［2,3］, Hui Yu^［5］, the texture features we present have the best texture discrimination performance.

Abstract:The indirect boundary element method (BEM) is presented. The wave propagation in cracked media is solved by means of 2-D dynamic boundary integral equation. A 2-D BEM program is developed to model the elastic waves excited by a point explosive source propagating in the fractured rocks. Numerical results show that the BEM is an effective method for seismic wave modeling.

Abstract:A plate structure is a structure made up of several plates. To solve the bending problem of orthotropic plate, a general analytical solution of partial differential equation for transverse displacement function of orthotropic rectangular plates in bending must be worked out. It can be used to solve the bending problem for arbitrary boundaries and arbitrary load. For each plate; some edges are independent which can be calculated by boundary conditions, while some edges are connected by other plates which can be calculated by continuous conditions. With the equations made up of these conditions, it can be used to solve all the integral constants in general solutions. For example, a water tank under hydrostatic pressure with the edges simply supported at the top and fixed at the bottom has been calculated.

Abstract:Two-stage iterative method is comprised by the inner and outer iteration and the numbers of inner iteration. We find out an upper bound of R₁-factor of two-stage iterative methods for solution of linear systems. And the upper bound is expressed applying the R₁-factors of the inner and outer iteration and the numbers of the inner iteration; the premier parts of the upper bound is the R₁-factor of outer iteration. Furthermore, for any inner iteration method and any numbers of the inner iteration, it is also showed that the lower bound of the R₁-factor of the two-stage iterative method can also be given by the R₁-factor of the outer iteration in the case of monotone matrices. The results indicate the effects of convergence rates of the inner and outer iteration and the numbers of inner iteration on the convergence rates of the two-stage iterative method.

Abstract:The simulation engine (SE) is the most important federate among the federations based on HLA. This paper puts forward a simulation scheduling architecture including SE,federate vessel and entity.And then it raises a hiberarchy　simulation schedule arithmetic based on time sequence and event sequence.At last, we introduce the design and implementation of the federate framework of SE,which is applied in efficiency simulation and the evaluation system of C³ I.

Abstract:Based on the difference of the combat ability of equipments and the influence of life cycle phase on the combat ability of equipments, the system dynamics' model on macroscopical control analysis of the life cycle costs of equipments is set up, which describes the relations between all the phases of the weapons' life cycle objectively and soundly. By simulation experiment of macroscopical control analysis of the life cycle costs of equipments, some experimental conclusions have valuable reference to the construction and development of equipments.

Abstract:Active Queue Management(AQM) is an effective method to improve the performance of end-to-end congestion control. PI controller is a popular AQM scheme having good steady-state properties. We present the guidelines for setting parameters of PI controller using the “second-order optimization model” instead of the margin of stability to improve transient behavior. The performance of PI controller with new parameters is verified and compared with that of default ns parameters using ns simulations. The results show that the dynamic behavior of PI controller is improved. We present several future directions in the end.

Abstract:We consider the following neutral functional differential equation with piecewise constant delay:d²/dt²(x(t)+p(t)x(t-1))=qx(2［t+1/2])+g(t,x(t),x［t］)By using fixed point theorem and the method of pseudo-almost periodic sequence, we get the existence of the pseudo-almost periodic solution of this equation. Also, some results in reference ［5～8］ have been extended.

Abstract:In order to enhance the scientificity of making the blending plan of refineries, the nonlinear programming (NLP) models of the blending optimization problems was researched in detail, including the formulation of the objective function and constraints. The simulated annealing algorithm is selected to solve the problem according to the characteristics of the model. Finally, the validity of blending optimization model is verified by the application of a refinery.