Abstract:In this paper, the time-dependent numerical method is used to solve the three dimensional Navier-Stokes equation. In the numerical procedure, Roe's flux difference splitting technique and Chakravarthy-Osher TVD scheme are used for the pressure and convective terms. Numerical solution of the Hypersonic laminer flow over a blunt biconic with 4°and 12°attack angle is obtained. The emphasis is placed on the predictions of the heat transfer rate on the wall. The numerical results of Stanton number are compared with the experimental data. And the multigrid method is also used to accelerate the convergence.

Abstract:In this paper, the domain decomposition technique (DDT) and the parallel strategy of patched grid are used. The parallel numerical calculation on multiprocessors with TVD implicit finite volume algorithm is carried out for three dimensional hypersonic viscous flowfield by balancing load. The high speedup (the speedup is 1.84 on two processors and 3.44 on the four processors) has been obtained.

Abstract:The paper studies the Lagrangian method for complex Multi-Rigid-Body system. On the basis of Mathematica system, the computer modeling, reduction and simulation of the Multi-Rigid-Body dynamics system are completed.

Abstract:Helmholtz resonators and quarter-wave resonators are studied as the high-frequency combustion instabilities suppression devices in liquid rocket engines. Proper selection of the number of the resonators within the absorber arrangement is discussed. The damping characteristics of various length resonators are compared. Optimizing the system's damping by means of the absorption coefficient is suggested. The valuable results are proposed for designers.

Abstract:Much inportance has been attachad to the selection of optimal feature parameters subset in the fault diagnosis fields such as liquid rocket propulsion system. This paper presents an effective method of selection for the optimal feature parameters subset using Genetic Algorithms and based on the maximum and minimum clustering criterion for samples, so that the selected feature parameters subset can be used to compose a simplified real-time fault classifier with high robustness to various sorts of noises and distur-bances. First, a composite directional divergence index for samples is proposed as an evaluation criterion for the selected feature parameters subset for fault diagnosis 'purpose; then, Genetic Algorithm has been modified in parts for this specific permutation problem, the dynamic fitness adaptation technique and all-sharing function are introduced in order to avoid the population's premature convergence. An ad-hoc genetic operator is specially designed to improve the feature selection efficiency. In an addition, all the selection procedures for the optimal feature parameters subset are based on the data set for 16 sorts of common faults simulated for a type of liquid rocket engine system. The numerical experiments show that this selection algorithm is highly effective and the constructed fault classifier with the selected feature parameters possesses morerobustness.

Abstract:A general method for the cycle power balance calculation of the liquid rocket engine is proposed in this paper. The components of the engine system are calculated iteratively in a predetermined sequence, and a modified Newton method is used to find the unknown variables of the system. This method is universal for the analysis of liquid rocket engine cycles. The program based on the method is achicved by the object-oriented programming. The stage combustion cycle using the liquid oxygen and methane as propellant is calculated with the program, and the calculation results are also given.

Abstract:The drawbacks of the traditional Kalman filter arise from its requirement of accurate model and noise statistics which generally can' t be satisfied in engineering applications. An improved Kalman filter including inaccuracy in filter's initial condition is presented in this paper. By reducing the requirement of model accuracy, it can improves the robustness of Kalman filter under the model mismatch. Fault detection with this filter reduces the fault alarm rate owing to its stronger robustness. Because the accuracy of missile attitude control system model is limited, it is difficult to detect fault for the traditional Kalman filter owing to its weak robustness. The improved algorithm can detect faults effectively . A simulation example shows its validity.

Abstract:Based on the analysis of the system structure, information flow path of the flexible machining device, we have built up the precise dynamic model of mechanical-electronic systems of the machining center, and developed the hardware to realize the real-time identification of parameters of the models. It is a strong base both for building up a real-time condition monitoring, fault diagnosis and prediction system and for getting rid of the influence of the changeful machining mode and the factor of time-varying in the FMS environments.

Abstract:Distributed object computing is the main-stream technology of enterprise application integration. This paper introduces the structure of the framework supporting platform based on distributed object technique. Then it proposes the architecture of a CAD framework for large-scale electronic device, and presents a framework model based on framework bus and soft component. Finally, the paper discusses the implementation methods and technologies of integrated framework.

Abstract:The problem of tracking a maneuvering target in a cluttered environment by multuple radars is considered. This paper presents a distributed fusion algorithm. The local nodes transmit their estimation results to the fusion node, where the local estimation results are combined to obtain global estimation. The Monto-Carlo simulation shows that the distributed fusion algorithm performs much better than the local estimation algorithm in every function index and achieves the expected effect.

Abstract:The algorithm of position location with two coordinate measurements in bistatic radar is presented in this paper, which uses the measurements of slant range and the azimuth referred to T/R station or the ones of range sum (target to T/R and R) and the azimuth to R station. The analysis method of the position location accuracy is given. Finally, the performances of these algorithms are evaluated by computer simulations.

Abstract:A new exact, explicit, uniterative, and computationally effcient solution of nonlinear equation set for estimation of emitter position based on the time differences of arrival (TDOA) measured by multi-stations is proposed in this paper. The accuracy analysis of the location method is also presented. Finally performance evaluation results of emitter location by using TDOA information are illustrated by some graphs of Geometrical Dilution of Precision (GDOP) under various conditions in the specific surveillance region.

Abstract:In this paper it is presented to resolve the dithering infrared target detection problem under the condition of low SNR. Accumulation of multiframes is often adopted in low SNR infrared target detection, but for dithering low SNR target, this simple accumulation scheme maybe degrade greatly. In this paper, detection algorithm based on dilation before accumulation of multiframes and track before detection is proposed. The dilation operation enables the energy of the same target in different frames to accumulate effectively dispite of the dithering of target, thus we can reach the aim of enhencing the target. The false alarm candidates are removed in the procedure of track before detection. A preprocessing algorithm using wavelet transform is also adopted to remove the correlation of 1/f noise. At the end of this paper, the whole algorithm is simulated with infrared image sequence. A high performance is obtained and the experimental result indicates that the algorithm can effectively detect the target with SNR=2.

Abstract:This paper introduces the recently developed chaos and multifractal theory into the fields of radar signal processing for radar target characteristic and recognition. The Lyapunov exponents of five kinds of planes are calculated. With the correlation integral method, the multifractal dimensions of these targets's cattering signal are further obtained. Then we carry on the experiment of radar target recognition and get satiafactory recognition-rate. The results of this paper show that the chaos and multifractal theory have great potentials in the fields of tadar signal processing and target recognition.

Abstract:The characteristics of impulse signal synthetic aperture radar (SAR) imaging are analyzed in this paper. It is shown that the linear array model is an efficient interpretation to the azimuth integration of an impulse SAR. Back projection (BP) method can be comprehended easily with a linear array model. With respect to the algorithm realization in a field system, the BPIQ method with back projection to I, Q channels respectively and then evaluating the module of two integration's is presented. Computer simulations show that the imaging results of BPIQ are better than those of the ordinary BP algorithm.

Abstract:The paper discuss the several key factors influencing the performance of wavelet transformation compression in detail. By comparing the different choices, we get the optimal one. Good results are obtained by applying them to remote sensing image compression.

Abstract:GX2500A Graphics System is an important component part of the GX2500 Ultra-high Resolution Display System. The display resolution of this system is up to 2048×2048 pixels. GX2500A Graphics system provieds two software environment for application, one supportsing programming based on PC Microcomputer Programming Language and the other based on Tms34010 Programming Language, so it is adaptable for various users. This paper describes the hardware design and software design of GX2500A Graphics System.

Abstract:The reflective itensity-modulated optical fiber sensor for measuring displacement, the antenna-shaped optical fiber sensor, is usually composed of a fiber bundle with the emitting and receiving fibers in a specific arrangement at the probe tip. The three elementary types of fiber arrangement are: concentric distribution, semicircular distribution and random distribution. In comparison with the size of the optical fiber sensor, the thickness of clad and binding element of the fibers is so small that it can be ignored. The mathematical models of the modulation function for the single fiber couple composed of both an emitting fiber and a receiving one are presented. After analyzing the distribution of the fibers inside the optic fiber sensor by using the geometric and statistical theories, the general mathematical models of modulation function for the three types of the sensors mentioned above are proposed. And all the models are simulated with computer and all the simulating results are briefly analyzed.

Abstract:This paper firstly extends the self-organizing neural networks to general case. Then the self-organizing process is applied to classify the dynamic process of nonlinear control systems. The nonlinear system is self-organized according to the probability density of the input and output samples and is approximated by many linear sub-spaces with different classifying centers and receptive fields. The self-organizing least squares identification of nonlinear systems is constructed based on the general least squares algorithms, the linearization errors of sub-spaces, and the cooperation and competition mechanism. The simulation results have shown the efficiency of the suggested algorithm.

Abstract:Future integrated-services networks are expected to support applications with a wide range of service requirements. Bounded delay service supports deterministic guarantees on maximum delay for connections. This paper first presents the architecture of network with a bounded delay service and introduces the functions and work principles of the key components of the network in tail. Various issues and tradeoffs in designing bounded delay network are presented finally.

Abstract:Titanium oxide gel was preared from n-butyl titanate by a sol-gel method, The gel was then sintered to form TiO₂ ceramic. From the TiO₂ powder, titanium nitride formed through nitrifying by ammonia at the temperature above 900℃. The processes were intensely studied through thermal analysis, chromotography, scanning electronic microscopy and X-ray diffraction. Emphasis is placed on the chemical reations, the crystalliztion and polyamorphism in the sol-gel process of TiO₂. Thereafter, the dependence of the yield of TiN under the preparatory conditions of TiO₂ is established.

Abstract:Several SiCw/Si₃N₄ ceramic matrix composites with Y₂O₃-Al₂O₃ and. Y₂O₃-La₂O₂ sintering additives are made by hot-pressing method in this paper. The results show that the type and composition of sintering additives have obvious effect on the bonding strength and fracture tonghness of the composites, especially at high temperatures.

Abstract:This paper discusses the invertibility of single-input single-output linear systems. A new method for construction the reduced inverse systems is derived. Compared with the reduced inverse systems given by H. L. Silverman, our new reduced inverse systems have lower order|simpler structure and reveals the connection between the rank of observability matrices and the order of inverse systems.

Abstract:Discrete Approximation is an effcient research means for continuous parameter oprimal sropping theory and Markov processes optimal stopping theory. This paper expounds this means in detail, and also uses it to solve two practical problems.