Abstract:To provide an efficient way easy to express and organize the fault knowledge of liquid rocket engine, a qualitative model is first founded by the qualitative description of the observation and characteristic of the system in the form of propositional logic formulae and clauses, then fault diagnosis is continued based on the inference rules of resolution step and modus ponens, and diagnosis results with test data manifest that the provided method has better ability.

Abstract:A fuzzy control is studied, which is used for the feedback control in the changing condition process of the staged combustion cycle liquid rocket engine. Simulation research has shown that the fuzzy sliding mode control surpasses usual variable structure control in weakening chattering.

Abstract:The launching cost model of reusable launching vehicle based on Life-Cycle-Cost(LCC) analysis is presented. The LCC of various reusable launching vehicle programs with different stages are calculated by applying the newly built analysis model. Components of the LCC are presented specially, and the relationship between each of the components of the LCC and stage number is also analyzed. The result indicates that the LCC of Two-Stage-to-Orbit (TSTO) reusable launching vehicle program is the lowest, so TSTO reusable launching vehicle program is the relatively optimal selection based on the present developing level.

Abstract:By means of the finite difference scheme of characteristic method, the transient flows are simulated for the attitude control propulsion subsystem during the pulse operation. The effect of different conditions on dynamic behavior in pulse mode is investigated. The results are agreeable with the test process. The method can be used to analyze the dynamic performance of complex propulsion system consisting of numerous pipes, valves and thrusters. The results are valuable for designers.

Abstract:Complicated flow field of shock/boundary layer interaction in the supersonic diffuser is simulated by solving the Reynolds-averaged Navier-stokes equations in 2D,axisymmetric and 3D cases. The length of shock train, the distance of each shocks in it and the level of pressure recovered are compared with each case. Also, the oscillation phenomenon of the shock train is captured through Runge-Kutta method when the freestream mach number is 3 and the results are compared with experimental data.

Abstract:A mixed variables transfer function is presented for analyzing the stability of orthotropic cylindrical shells and stepped cylindrical shells. First, displacement variables are expanded in trigonometric series of circumferential coordinate. Flügge thin shell theory and variational principle are adopted to obtain governing equations and find dual force variables. Consequently, governing equations are written in the form of mixed variables. State-space equation of the system is established by defining mixed state variables. Then, by transfer function method, closed-formed solutions for buckling problems of cylindrical shells under axial compression with arbitrary axisymmetric boundary conditions are obtained. Finally, solutions for buckling problems of stepped cylindrical shells are obtained by enforcing displacement continuity and force balance. Driving process of analytical solutions show that it is very convenient for introducing boundary conditions and solving the buckling problems of stepped cylindrical shells in this method. Numerical results validate this method.

Abstract:In the case of the formation flying constellation, this paper discusses some problems about the determination of relative states, which includes the relative position, attitude and time between the formation flying satellites, by using precise pseudo-ranging. The problems are the selection of coordinate system and independent state parameters, the setting of observation equations, conversion of constellation's states, orientation and installing of antenna. Numerical simulation and analysis are made for an earth-observation constellation.

Abstract:Composite material plate usually is anisotropic plate, To solve the bending problem for plate, trigonometric series solution in complex number form and double sine series solution are used to establish a general solution of differential equation for anisotropic thin plates in bending problem. It can be used to solve bending problem for arbitrary loading with whatever boundaries. As an example a square plate with four edges fixed has been calculated. The result agrees with that in literature. This common analytical method is simple and complete, and easy to use in practice.

Abstract:The study is aimed at the inorganic process of the cured PCS fiber, the preparation of SiC fiber. Much work is done on elemental fields of the affections of the amount of the cured PCS fiber and the protective gas flow etc on the pyrolysis. We find through the experience that it is the offgas evacuated in the process that plays an important role by accelerating pyrolysis and increasing the weight loss. The explanation is that the living radicals in the offgas prevent the split chain radicals from recombination and the chains turned to be shorter and more degradable.

Abstract:As a preceramic polymer to silicon carbide fibers, polycarbosilane (PCS) should have both a relatively higher melting point (m.p.) and a relatively good spinnability. However,to increase m.p. means a rigid requirement for the synthesis conditions. To solve this problem, we firstly obtain a higher m.p. (>280℃) PCS fraction via fractional precipitation,and then add 10-30wt% of a lower m.p. fraction to above PCS,thus obtain PCS mixture,then,both have a higher m.p. (>250℃) and a relatively good spinnability.

Abstract:The basic principle of fast calculation of the Fredholm equation of the second kind based on Lanczos technique is introduced. The method of moments in conjunction with Lanczos technique is applied to predict the mono-static radar cross section (RCS) of an arbitrarily shaped two-dimensional dielectric cylinder. The electric field integral equation (EFIE) in the dielectric cylinder is established firstly, and then EFIE using the method of moments is changed into the matrix equation, and the electric field in the dielectric cylinder is obtained by solving the matrix equation using Lanczos technique. It is observed that the Lanczos technique can result in considerable CPU time saving.

Abstract:At first, the principle of algebraic quadratic congruence mapping is analysed, and then limitation of odd-even protection and shift computation are added to the mapping of interleaver. Two new improved interleaving algorithms are obtained. It is proved that the performance of the improved interleaver is better than the traditional block interleaver under comparable complexity by simulation.

Abstract:Classical sampling theorem establishes the relationship between the band-limited signal and its uniform samples. This paper reinforces it in three aspects. First, the error formula of the reconstructed signal and the original signal is presented when the theorem conditions are not satisfied. Second, this paper analyzes the uniform sampling of the band-pass signal using concise method, and then gets the conditions which the sampling frequency should satisfy. Last, the nonuniform sampling of the band-pass signal is studied. The consent range for sampling frequency and the reconstructed formula from its nonuniform samples are presented. All this enriches and deepens the classical sampling theorem.

Abstract:A new way for detecting the targets through images is proposed, and then using it, a new method for extracting texts is proposed. This method can be used not only to index the image database and the video, but also to invert the documents in papers to electrical text format. It can be divided into two steps. In the first step, the candidate regions, which can include texts, are extracted, in the second step the candidate regions are verified by analyzing the distribution of gray value of the scan lines by Hough transform method. The shape of the extracted regions is also pruned to contain texts compactly. This new method can be used to extract texts with different sizes, orientations, fonts and gray values or colorsBecause all operations of the new method are based on pixels, the new method can be realized by hardware easily. The experiments we have done justify its validity.

Abstract:The finite-difference time-domain method (FDTD) is used to analyze the slots feed of paraboloidal reflector antenna. The effects of feed waveguide and shape of radiation slots on feed patterns are also discussed. The paraboloidal reflector antenna patterns are presented by using physical optics, and the numerical results are compared with experimental results, and the comparison shows excellent agreement over a wide angle.

Abstract:A model called imposed excitation method for targets on the ground in time domain is described.The method comprises two steps：in the first step the scattering of the ground is calculated;in the second step the scattering of targets is calculated by imposing the scattering wave got at the first step upon the targets.A truck is involved in this paper.The scattering waves and RCS in VHF/UHF frequency are calculated.Good agreement between calculated and experimental results is obtained.It shows the effectiveness of the method.

Abstract:In the application of GIS, there is a need to manage spatial data. For this purpose spatial database systems are designed to be full-fledged database systems with additional capabilities for storing, retrieving, manipulating, and querying spatial data. But there are many difficulties to manage spatial data using spatial databases, such as numerical robustness and topological correctness. To solve these problems, we introduce some new concepts about Regularly Spatial Discrete Domains (RSDD), RSDD-based Primary Object (RPO), RSDD-based Object (RO), and defined the spatial data types and their operations over RSDD. As in a computer system, it is feasible only with limited precision, i.e., over a finite, discrete, and homogeneous grid, this strategy is ad hoc suitable for correct finite-precision implementations of geometric algorithms.

Abstract:This paper first introduces the basic concepts and methods of hook technology. Then analyzes some major hooks and their usage in software development. Finally, how to use hook technology in the processes of developing the Electronic Dictionary and the Wheel Mouse driver is described in detail.

Abstract:Some uncertainty and nonlinear factors of feeding mechanism have a powerful negative effect on tracking accuracy of ultra-precision machine.The quantitative feedback theory is a controller design method in frequency domain.It is aimed at designing a low order robust controller under plant uncertainty and disturbance.A robust QFT tracking controller with velocity feed forward & integral control is designed in the paper.The simulation result shows that 0.01μm tracking accuracy is achieved with the controller.

Abstract:In order to improve the efficiency of the data transfer and management in DIS, the framework based on soft Agent of the distributed simulation data management and transfer is presented. The soft Agent technicality has been used in the development of the network interface unit to form the intelligent network interface unit used in the distributed simulation platform. It is easier and more effective to manage the distributed, heterogeneous and integrated environment as well as to promote the simulation speed in every simulation station.

Abstract:The neural network is applied for the error model building of NC machine tool. Taking a precision aerostatic granite milling machine as the research object, an accuracy model of the milling machine is established, a special gauge is designed, and a training sample is constructed as well. Positioning accuracy of the machine tool can be forecasted by the neural network accuracy model. The results show that the scheme is feasible.

Abstract:Grey system is extended to probability stat. theory. Grey probability axiom system is expounded. grey probability density function and Grey reliability calculating method are studied. Then, stress-strength interference grey reliability calculating model and its whitening solution method are established. The program is worked out with Matlab5.3.1 language. Some examples are given, balance analysis is made for the general reliability design method and it displays that this model is accurate & feasible,and can be used to implement sensitive analysis and robust reliability design when their parameters are changed to effectively control design parameters.

Abstract:This paper presents a real time image processing system, with a stereo color image instrument being chained to Matlab platform, for automatically identifying automobiles ahead and then calculating the distance between the instrument and the object. A fuzzy rule based on a color model (hue-saturation-value) is proposed to extract the color characteristic of the taillights, motivated by the fact that all the automobiles have a pair of red color taillights and the HSV model conforms to the color consistency of human vision system. In order to accommodate varying background colors and illumination conditions, the rear window or the shadow of a automobile is further identified by using the value information in the HSV model. Moreover, a new algorithm is presented here for quick filtering out the noise consisted of the granulated or slim pixels. Finally, experimental results are reported and analyzed.

Abstract:In the field of reflective fiber-optic displacement sensor, in order to improve the displacement measuring accuracy, two receiving fibers are often used for intensity and reflectivity compensation. Based on the mathematic model of light coupling between the fiber pair, three types of tri-fiber optic sensors are studied. The general mathematic model of the tri-fiber sensors is proposed. Simulation about them is finished. Research shows that these kinds of tri-fiber sensors can not only improve the linear range, linearity and displacement measuring sensitivity, but also eliminate the influence caused by power fluctuation of the light source and variety of surface reflectivity.