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1999 Vol. 25, No. 5

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Analysis on Arrangement of Hybrid Composites Reinforced with Different Diameter Fibers
Zhang Zuoguang, Zhong Weihong, Zhang Daxing, Shi Weihua
1999, 25(5): 499-501.
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It mainly explored the hybrid model and mechanism of two kinds of hybrid composite materials reinforced with different diameter fibers which were composed of small-diameter fibers nested between large-diameter fibers in a matrix. T300 carbon fiber(CF), SiC fiber and boron fiber(BF) were used. Three types of single fiber composites and hybrid composites with carbon fibers as small-diameter fibers, SiC and boron fibers as large-diameter fibers in epoxy resin matrix were constructed. Triangle and quadrilateral formations were proposed as the hybrid models. The effects of processing on hybrid arrangement and fiber volume fraction were analyzed.
Half-Quantification of High Strength Aluminum Alloy's Corrosion Rank
Xie Weijie, Li Di, Hu Yanling, Guo Baolan
1999, 25(5): 502-504.
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Corrosion rank of high strength aluminum alloy in aircraft by visional inspection is a qualitative but simple method,while the most reliable parameter that reflects the corrosion of aluminum is the maximum corrosion depth.In order to make corrosion rank more reliable, corrosion rank and maximum corrosion depth of two high strength aluminum alloys (LY12CZ and 7075T7351) in EXCO solution was measured.At each corrosion rank,a number of corrosion depth data were obtained.With the statistic analysis, the relationship between the rank and the depth was established.So,corrosion rank of LY12CZ and 7075T7351 aluminum alloy in EXCO solution was half-quantified. By determining corrosion rank, the maximum corrosion depth of LY12CZ and 7075T7351 aluminum alloy can be evaluated approximately.
GRECO Geometry Fitting by Using VC++4.0
Ning Huansheng, Gao Ying, Wang Baofa
1999, 25(5): 505-508.
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GERCO(Graphical Electromagnetic Computing) is recognized as one of the most valuable methods for computing the high-frequency RCS (Radar Cross Section). To the complex radar targets, in order to obtain a satisfying result, the target geometry fitting is an important work in applying the GRECO method. This paper shows the principle method by using Catmull-Rom spline function geometry fitting theory, Visual C+ + language and OpenGL in Windows NT system. It gives the RCS curves of a standard body and a complex radar target, which are satisfying measured results. The results can have practical engineering worth.
Wavelet Transform-Based Approach for Interferometric SAR Image Noise Reduction
Yuan Yunneng, Hu Qingdong, Mao Shiyi
1999, 25(5): 509-512.
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Thermal and "Speckle" noise is an obstacle to obtain high accuracy phase in interferometric SAR images. According to the main sources of noise in interferogram, the noise character and the characteristics of interferometric SAR processing, biorthogonal wavelet transform with symmetry and compact support is introduced into the reduction of noise in interferometric SAR images. Based on the wavelet frame representation, a new algorithm for noise suppression in interferogram is proposed. Compared with the traditional low pass filter and median filter, it is showed that applying wavelet transform to the noise reduction in interferometric SAR images is promising. Furthermore, wavelet-transform-denoise is also the adaptive algorithm based on the observation data.
Study of GPS/DR Integrated Navigation System for Vehicle
Zheng Pingfang, Chang Qing, Zhang Qishan
1999, 25(5): 513-516.
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The design of the GPS/DR integrated navigation system is presented and the main error sources which affect the GPS/DR system position accuracy are also analyzed. A mathematical model is founded to represent these main errors and an extended,iterated and federated Kalman filter algorithm is propounded which is based on compensating for some observation errors according to the principle of data fusion of the GPS/DR integrated system for vehicle. The Experimental results demonstrate that this filter algorithm can improve the positioning accuracy of the GPS system , correct the accumulating error of the DR system at the same time, and enhance the GPS/DR integrated system reliability and integrity greatly.
RCS Computation of Low-Scattering Targets by Hybrid Method of\= GRECO and Traveling Wave Theory
Ning Huansheng, Jiang Xin, Wang Baofa
1999, 25(5): 517-520.
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GERCO(Graphical Electromagnetic Computing) is recognized as one of the most valuable methods of RCS computation for the high-frequency region. To the low RCS target, the effect of traveling wave is remarkable and larger than that of facets and wedges in some cases. This paper shows satisfying results by using the hybrid method of GRECO and traveling wave theory. It gives the RCS curves of a low scattering prop, which are satisfying measured results. The results can have practical engineering worth.
Research and Development on Automatic Dependent Surveillance System Based on VHF Datalink
Zhang Xuejun, Qu Jianming, Zhang Qishan
1999, 25(5): 521-523.
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The basic concept, construction principle and implementation for the ADS(Automatic Dependent Surveillance) system are presented. The tracking precision is one of the most important factors of the practicality of ADS system. The outburst disturbance and the lose of ADS message and error code caused by the change of plane' s attitude severely affect the tracking precision of ADS system. An Kalman filtering algorithm based on the "Current" model is adopted to process the ADS data to improve the tracking precision of ADS system. Numerical simulation shows that this method is effective. This Kalman filtering algorithm makes the ADS system more practicable for ATC(Air Traffic Control).
Clock Synchronization Method and Performance Evaluation on a Class of Hybrid Systems
Cheng Changdong, Wen Chuanyuan
1999, 25(5): 524-526.
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During the simulation of a class of hybrid systems which consist of continuous systems, discrete event systems and inference decision systems, because the simulation of inference decision systems depends on other two systems, there are only different private simulation clocks between continuous systems and discrete event systems. This paper studies their simulation clock synchronization problem, and the equal step length synchronization method which bases on the equal step length of continuous system simulation, and the software realization method is given. Finally, the performance valuation method is also given, which can provide theoretical basis for the simulation of this class of hybrid systems.
Study of Task Assignment of Aircraft Onboard Machine-Electronic Equipment Control and Management Integrated
Li Yang, Wang Zhanlin, Qiu Lihua
1999, 25(5): 527-530.
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It's a trend that the aircraft onboard machine-electronic equipment is controlled and managed integrated by using the distributed processors and the network technology. How to assign the tasks of control and management to the distributed processors to balance the risk factor of system is the key technology in the problem of integrated control and management. It's also the main technology to improve the system reliability and safety. The fact is a combinatorial optimization problem. In this paper, the task assignment rules and object function are presented. The best strategy of the task assignment is searched by using the genetic algorithm, and the results are illustrated.
Redundance Control of Servo Actuator System
Fu Yongling, Pei Zhongcai, Wang Zhanlin
1999, 25(5): 531-534.
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In order to improve the reliability of servo system, a triplex electro-hydraulic servo actuator system with three torque motors, three jet flapper valves and three sets of feedback components is designed. The authors make a deep theoretical analysis on the system, build up the mathematical model of the triplex electro-hydraulic servo actuator system, analyze the effects of the redundance control on dynamic performance of the system and the dynamic performance of triplex electro-hydraulic servo actuator system after any trouble happens. The results show when the triplex electro-hydraulic servo actuator system is applied, the dynamic performance has a little difference. When one coil of servo valve is broken, the system works in going order. This result proves that redundance control greatly improves the reliability of the servo actuator system, and provide the theoretical bases for the design of the servo actuator system with good performance.
Feature Modeling for Aeroengine Blades According to STEP
Zhao Wei, Ma Mei
1999, 25(5): 535-538.
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Feature-based aeroengine blades design is researched in concurrent engineering environment. Based on the analysis of the basic features of various aeroengine blades, parametric feature modeling technology and object-oriented method, feature architecture of aeroengine blades,and a 3D solid blade feature modeling system are developed according to STEP (AP203/AP214) on design platform LONICERA,which is an advanced integrated mechanical (CAD/CAM) design environment developed by Beijing University of Aeronautics and Astronautics. The data exchange with STEP is accomplished. A solid model is transmitted from design platform to analysis platform (MSC/ PATRAN/ NASTRAN), then strength and vibration analysis of a turbo-fan engine blade is carried out.
Inflow Models in Trim and Dynamics Response of Helicopter
Yang Chao, Hong Guanxin
1999, 25(5): 539-542.
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For the current helicopter of single main rotor with tail rotor, the effect of inflow models with different characteristics on helicopter trim and digital simulation was discussed. Based on Pitt/Peters' first order dynamics nonuniform inflow model, the effect of uniform and nonuniform inflow models of main rotor on helicopter trim, and the effect of uniform and nonuniform dynamics inflow models of main rotor on helicopter dynamics response to pilot control input at different forward flight speed states, were analyzed, which could provide useful reference to chose the proper inflow model of main rotor for different flight digital simulation. The sample of UH-60A Black Hawk helicopter was used for the calculation and analysis.
Fuzzy Optimization of the Geometrical Parameters of Fighter Inlet
Li Jing, Li Tian, Wu Zhe
1999, 25(5): 543-545.
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For two-dimensional, two-shock, all-external compression, supersonic, cheek-type inlet, the integrated aerodynamic-stealth design of geometrical parameters, such as width, ratio of width and height, angle of vertical compressing ramp, two cutting bevels of the lip plane and lip-position-angle, was investigated by considering those objectives such as the total pressure recovery coefficient, additional drag coefficient of supersonic overflow and the RCS(Radar Cross Section). The formulae for calculating the total pressure recovery coefficient, additional drag coefficient of supersonic overflow were derived. The satisfactory functions of the objectives and the restrictions were given, and then ,based on these functions, the multiobjective fuzzy optimization model was established.
Optimized Collocation of Combat Aircraft Weapon Systems for Air Force
Huang Jun, Wu Zhe, Zhu Rongchang
1999, 25(5): 546-549.
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The air force is one of the key elements in modern warfare and its main weapons are combat aircraft. Taking the campaign superiority parameter as objective function, a nonlinear programming for the combat aircraft weapon systems of air force was completed by using the complex method with constrains. The optimal collocation of the military airplanes under the limitations of equipping quantity and purchasing budget was worked out. An example indicates that the used mathematical models, method and arithmetic are correct and effective. It also shows that the established software system is quite practical and applicable. An explanation of the calculated results and evaluations for complex method and the software system were summed up in the conclusion.
Probability Damage Tolerance Evaluation Method for Multi-Cracked Structure under Pre-corrosion
Zhang Jianyu, Zhao Libin, Fei Binjun
1999, 25(5): 550-553.
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For analyzing the aircraft structural reliability under bad parking conditions, probability damage tolerance evaluation method is established. This method is used to analyze the reliability of multi-crack structure considering the influence of pre-corrosion. This method comprehensively surveys the existed single-crack propagation random model under pre-corrosion conditions using Wei-Landes linear theory and the crack propagation random model with multi-crack structure. Finally, the life-reliability curves are given in an illustrative example using the method as indicated above. Comparing the reliability curves of different SUS(Service Usage Severity), the influence of pre-corrosion and SUS to crack propagation life can be obtained.
Equal Damage Design Method for Fatigue Reliability Design of Structure
Xiong Junjiang
1999, 25(5): 554-557.
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The brief development course of fatigue reliability design is reviewed. The concept and principle of equal damage design for fatigue reliability design of structure are proposed. Then the test is carried out in order to validate this design principle, and it is indicated that the parts of a structure designed according to the equal damage design method have the same damage at the given life and break down at the same time. And so it is feasible and easy for the structure to be designed by means of the method presented in this paper, and this method can be conveniently used by the engineers. On the basis of this fatigue reliability design method, the structure may be designed to be safe, reliable and light.
Transient Performances Calculation of a Gas-to-Gas Crossflow Heat Exchanger
Song Junxiao, Yuan Xiugan, Lin Guiping
1999, 25(5): 558-560.
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The dynamic performance of a single pass gas-to-gas crossflow heat exchanger with high speed air flow that is used in airplane has been calculated with both lumped parameter model and numeric method model. The calculation results under typical conditions of these two methods are very similar,but the lumped parameter model is more simple than numeric method and easy to be used in programming. It also has satisfying precision and can meet the demand of system simulation.
Investigation into Shear Mechanical Properties of PUR Foamed Plastics
Lu Zixing, Xie Ruoze, Tian Changjin, Liu Xiaoping, Li Huaixiang
1999, 25(5): 561-564.
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The polyurethane rigid foamed plastics are important light structural materials. To investigate their shear mechanical properties is quite necessary for their applications.By the low speed torsional experiments of PUR foamed plastics, their shear mechanical behavior has been studied here. With these experiments, their shear properties such as the shear modulus and strength of PUR foamed plastics have been determined. Furthermore, the fracture surface SEM analyses of PUR foamed plastics have also been done to investigate the mechanism of shear failure in foamed plastics. Finally, the theoretical predictions for shear mechanical properties of PUR foamed plastics are given by means of author's theoretical formulae. The predicted results agree quite well with the experimental results. Particularly, some results obtained in this paper are firstly reported.
Computational Model of Progressive Failure in Composite Sandwich Structures
Zhang Zhimin, Li Jinqiu, Guo Yanyang
1999, 25(5): 565-568.
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Computational model of progressive failure in composite sandwich structures is built up to predict the face fracture,delamination failure and core failure. Nonlinear geometry equations and energy variational equation is estimated according to overall bulking of composite sandwich plates. The nonlinear stability governing equations of anti-symmetrical buckling of sandwich plate are deduced, considering the transverse shear deformation influence of core. In order to solve the governing equations, the method of generalized double Fourier series is employed. Tsai-Wu failure criteria and Maximum stress criteria are proposed to predict composite face-sheet failure,core failure and interlaminar failure. These failure criteria and stiffness reduction are used to obtain critical load,post-bulking behavior and limit load.
Dynamic Characteristics Simulation of Aircraft Anti-Skid Braking System
Shi Peitao, Wu Reixiang, hang Xienian, Hu Fengwu
1999, 25(5): 569-572.
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Based on the dynamic response of aircraft body, the spring, damping of landing gears, friction characteristics of the tires,sensors, and so on,mechanical model for aircraft anti-skid braking system is set up.The model is simple but practical and universal,which is integrated with velocity-rate-controlled and pressure-bias-modulated aircraft anti-skid system.Simulation software for braking design is developed and revised. By using the software and taking some fighter in China as an example,this paper discusses relation between the aircraft dynamic response and braking performance,especially the influence of landing gears and tires on braking performance.Some valuable conclusions, which are helpful to design and improve the aircraft anti-skid braking system,are drawn.
Design of Switched-Capacitor Filters Using Signal-Flow Graphs and General Integrator
Cheng Daiwei, Fan Tianying
1999, 25(5): 573-576.
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A new design method of switched-capacitor low-pass filter using signal-flow graphs and the general integrator is presented. The method is of simplicity, clear physical concept and convenience for use . It can also be applied easily to the design of other kinds of SCF(Switched-Capacitor Filter)(e.g. high-pass and band-pass etc). An example is given to show the design of a fifth-order ladder SCF,and the general-purpose circuits simulation programs Pspice5.0 is used to verify the design. It shows that the design method based on SFG(Signal Flow Graphs) and the general switched-capacitor integrator is efficient.
Research on Fitability in Precise Forming of Reflector Panels
Chen Xiao, Zhou Xianbin, Chang Hesheng
1999, 25(5): 577-580.
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In order to investigate the fitability in superprecise forming of double curvature panel based on "nails die and vacuum", the approximate generalized Fourier series solution is suggested for the bending problem of the rectangular thin plate supported at arbitrary points with large deflection. The solution is derived by means of the incremental method of load and displacement constraint, which can get the constrained force at the same time for the further iteration of contact state. It is applied to analyze the pattern of the part sinking. The computational results of the plates with several kinds of width and thickness are compared with the experiment. It shows that the accuracy is satisfying well. Finally the proximate range of the critical plate width under varied pressure is suggested and moreover the relevant rules on reduction of errors in fitability are proposed.
Experimental Investigation on Friction Coefficient of Ferromagnetic Flow with Applied Electric Fields
Zhu Runsheng, Zhang Jianbin, Wang Zhishan
1999, 25(5): 581-584.
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The frictional performance of steel-on-steel frictional pair under boundary lubrication with ferromagnetic flow added with additive and their friction coefficient by the action of applied electric fields are studied .The experimental results from the pin-on-disk tester show that the friction coefficient of ferromagnetic flow added with an additive can be changed by 23 percent by the action of oppositely directed applied direct currents ,so a new type of lubricating agent with controllable friction coefficient under boundary lubrication is obtained. It is possible to control friction coefficient actively with applied electric fields in order to reduce friction and energy loss.
Investigation on CAD of Composite Materials Entire-Body Special-Shaped Component
Duan Hongjie, Yan Deyuan
1999, 25(5): 585-587.
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For entire-body special-shaped component such as multi-branch entire-body special-shaped hollow composite material tressel, the complex curved surface construction and continuity in laying fiber become obstacle in CAD. So block-modeling and grid-refining are used to control the direction of the surface and generate equal-space grids. As a result, it is easier to generate the grids.The order and direction of the board layer are changed, the mechanical properties is analyzed and the design of component is optimized by means of testing and simulating with finite element software. The entire-body special-shaped racing bicycle,shaped by pouring resin into sewing exemplar, is proved to be acceptable after experiment and checking.This means that the method is practicable and can be used to design components of either aerostat and space craft or civil product.
Simulated Annealing Heuristic for Lot-Sizing Problem
Han Limin, Wang Fei, Feng Yuncheng
1999, 25(5): 588-591.
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The multi-item capacitated lot-sizing problem consists of determining the magnitude and the timing of some operations of durable results for several items in a finite number of processing periods so as to satisfy a known demand in each period. An approximation algorithm is described, which is based on simulated annealing algorithm. The method incorporates a primal partitioning scheme— with a network flow subproblem—to obtain good feasible solutions.
Principal-Agent Analysis under Stock-Cooperation System
Gao Yuanyang, Chen Liangyou, Yuan Zhishan
1999, 25(5): 592-595.
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This paper introduces an important characteristic of the enterprises under the stock-cooperation system, i.e. the internalization of the principal, which means the employees of the enterprise are both principals and agents at the same time. This point is taken into the principal-agent analysis of the enterprises with a simple model. The results show that under this system, although the allotment of shares of an enterprise has an important effect on employees' enthusiasm, it can't solve the employees' free-rider problem well and some incentive measures which are effective in other enterprises are probably no longer effective in this case.
Complexity of Motions of Gyroscope
Hu Zhixing, Guan Keying
1999, 25(5): 596-600.
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The motions of a gravity symmetric gyroscope, whose outer ring's axis is placed horizontally, are dealt with. Firstly, the motions of a free gyroscope are studied and explained in the sense of mechanics under a certain condition. The Melnikov's methods and KAM theory can be used to study the motions of a non-free gyroscope if its rotor's gravity center can be treated as a perturbation. It is shown that the motions of the non free gyroscope are chaotic in the sense of Smale horseshoe, and the KAM invariant tori and closed curves exist in the Hamiltonian flows of the perturbed system if the gravity center of the gyroscope's rotor doesn't coincide with the center of its supports, and the distance between them is sufficiently small, or its energy is sufficiently large in comparison with its potential energy.
Variable Structure Exponential Stabilization of Uncertain Nonholonomic Dynamic Systems
Wang Chaoli, Huo Wei, Dong Wenjie
1999, 25(5): 601-604.
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The chained form control system is a kind of canonical form of nonholonomic kinematic systems. Many nonholonomic kinematic systems can be transformed into this kind of form by coordinate and input transformations.Using variable structure control, a globally stabilizing controller is given directly based on nonholonomic dynamic systems with uncertainties when the nonholonomic constraints can be converted into chained form control systems. The proposed controller satisfies that there exists a finite time,after that time, the states of the closed loop system exponentially converge to zero with an arbitrarily given rate.The proposed result is used to stabilize a mobile robot.Simulation result shows that the approach is effective.
First-Order Second-Moment Reliability Method and Its Software
Zhang Jianguo
1999, 25(5): 605-606.
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The common software of the first-order second-moment reliability method is developed. It can be used to calculate the reliability of the non-linear function with normal, log-normal, extreme and truncated normal statistically dependent random variables. The calculation results show that this method is simple in iteration and converge fast. It can be used in practical engineering design, for example, the structure, mechanism and mechanical part design. This software is developed using block structure method, so it is convenient for further development. The random variables with the other kinds of distribution can be considered by developing the corespondent programs.
Research on Testability Allocation Method
Tian Zhong
1999, 25(5): 607-610.
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The relationship is studied between system testability index and the system element testability indexes,and the factors are analysed,which have influence on determining testability indexes.Then,the fundamental requirements,mathematical models and working procedure for testability allocation are derived.The paper presents four testability allocation methods that are applied to different conditions.The first two methods are based on system' s complexity (failure rate) and importance (fault affection).The third one is named weight allocation method in which some factors are considered carefully.The last allocation method is specially for those systems which contain some old units (products).These testability allocation methods are useful in practical system and equipment development process.
Failure Model Effect Analysis Expert System
Zhao Tingdi
1999, 25(5): 611-614.
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The FMEAES(Failure Model Effect Analysis Expert System) that applies the artificial intelligent is introduced. It is established based on expert knowledge and function/hardware reasoning combined with fault simulation of the EDA(Electronic Design Automation) and supported by the reliability CAD and the reliability information system and the fault diagnosis expert system to extend the knowledge base and to enhance the FMEAES's capability. The expert system structure and function, the function of the elements including the pretreatment part, the core of the FMEAES and the posttreatment part and the relationship of the elements of FMEAES is described.Then the function of the failure model selection and the fault simulation using the EDA software and the reasoning and analysis flow to perform function FMEA and hardware FMEA of the FMEAES is discussed in detail.
Design and Implementation of Fast Motion Estimation Algorithm
Liu Dechun, Zhou Xiaokuan
1999, 25(5): 615-618.
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By sacrificing matching quality to reach higher matching speed is the common shortage of the published fast motion estimation algorithms.Based on the analysis of the strong and weak points of those motion estimation algorithms,a new fast motion estimation algorithm,using improved searching approach and optimized implementation techniques,is presented. In the new algorithm ,the above-mentioned common shortage is eliminated. The speed of it can be compared with typical fast algorithm and the quality of it can be compared with the exhaustive searching algorithm. The principle,implementation technique and final testing results of the algorithm are also given.
Study on Fault Monitoring and Diagnosis Techniques for Thrust Chamber and Turbo-pump Systems of Liquid Rocket Engines
Yang Erfu, Zhang Zhenpeng, Cui Dingjun
1999, 25(5): 619-622.
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It is shown that most of the failures of liquid propellant rocket engines pressured by turbo pump systems take place at thrust chamber and turbo pump systems.A brief introduction to the study on fault monitoring and diagnosis techniques for thrust chamber and turbo-pump systems of liquid propellant rocket engines has been made. The main contents are faults statistics and property analysis of fire-tests results, failure modes and effect analysis, the design and realization of failure database system, condition classifiers and character analysis, and so on. In addition, several algorithms for fault monitoring and diagnosis are also included. Finally, an engineering application system for fault monitoring and diagnosis of thrust chamber and turbo-pump systems is demonstrated and some application samples are also illustrated.

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