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1999 Vol. 25, No. 4

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Conductive Rubber Composite of SIS/LPB/Pan
Chen Yichi, Yin Wusheng
1999, 25(4): 375-377.
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SIS(styrene-isoprene-styrene)/LPB(liquid polybutadiene) rubber matrix by the in-situ polymerization to form a mono-face conductive rubber complex.The effects of the crosslinking degree of the polymer matrix,the amounts of aniline and the oxidant,as well as the polymerization time on the conducting properties of the complex were studied.The conductivity of the conductive surface is up to 5.5 S/ｍ while the PAn content is only of 6.1%. The conductivity of the complex:(1)decreased with the increasing crosslinking degree of the matrix,(2)increased with the amount of aniline,(3)increased firstly and then decreased with the increasing amount of the oxidant.
Experimental Study on UHMWPE (Dyneema UD66) Fiber Composite Armors
Zhang Daxing, Zhang Zuoguang, Zhong Weihong, Sun Zhijie
1999, 25(4): 378-380.
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The variation of the ballistic absorption energy of Dyneema UD66 fiber composite,an ultra-high molecular polyethylene fiber reinforced composite,with molding pressure,areal density and projectile velocity is studied.The molding pressure of UD66 fiber composite has direct effects on the ballistic absorption energy,so the relation of molding pressure with the adhesive bonding force between layers,the thickness of the laminates and density is investigated during the optimum of the molding parameters.The result shows that when the molding pressure is about 2.5MPa,the ballistic absorption energy is up to the highest value.For the study of the principles of the ballistic absorption energy,the deformation and fracture area of the UD66 fiber composite armors after ballistic impact are analyzed.The study results would be valuable for the optimum design.
Control of Message Priorities for Token Passing Networks
Xiong Huagang Luo Zhiqiang Li Jingsheng
1999, 25(4): 381-383.
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The transmission mechanism of the messages with their priorities for token passing networks was studied.A new method to determine the value of token rotation timers is proposed,which makes messages to be transmitted according to their maximum allowable latency sizes,from small to big,and meets all the message latency requirements under certain network load.Results of our algorithm have considerable precision comparing to outcomes of method presented in LTPB design handbook,which validates that our analysis and algorithm is practical.
Design and Realization of GLONASS Receiver Frequency Synthesizer
Liu Hui, Zhang Qishan
1999, 25(4): 384-387.
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A GLONASS receiver front end structure and its frequency synthesizer part are given based on the GLONASS frequency plan. The synthesizer is realized with integrated PLL frequency synthesizer. It is easy to be constructed and also has the advantage of good stability. The design details of the frequency synthesizer is given. The inherent synthesizing error is analyzed and the method of eliminating it is discussed. The theoretical performance of the synthesizer is provided. The experiments show that the synthesizer has good stability and high precision. It meets the requirements and can be applied to the GLONASS receiver.
Multi-reflection Calculation of RCS and Programing
Han Xuewen, Lü Shanwei
1999, 25(4): 388-391.
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The method to calculate the multi-reflection in RCS is discussed. It mainly considered the interaction of facet and facet by using the geography optics(GO) and physical optics(PO) in calculation . In the calculation of the total RCS, we also use the equivalent currents method(ECM) to calculate the contribution of edge . It also gives the method of how to complete the multi-reflection calculation by program . Finally, some examples calculated by this program are given . Results computed are in good agreement with experimental data previously.
Representation of Signal in Tight Wavelet Frame and Best Wavelet Base
Yuan Yunneng, Mao Shiyi
1999, 25(4): 392-397.
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The subject on the representation of signal in tight wavelet frame and the selection of the best wavelet base was discussed. The relation between the wavelet frame representation and the wavelet base representations, which is very useful for interpreting the wavelet frame representation, is described. then the Mallat-pyramid algorithm for periodic tight wavelet frame decomposition and reconstruction is derived and it is proven that periodic wavelet frame by periodizing the tight wavelet frame with bound 1 in is a tight wavelet frame with bound 1. Finally based on the wavelet frame algorithm and criterion of minimizing an additive cost function, the selecting best wavelet base algorithm is proposed.
Research on Problems of Motion Compensationin Chirp-scaling Algorithm
Li Liwei, Jia Hongjiang, Asif Raza, Mao Shiyi
1999, 25(4): 398-401.
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The chirp-scaling algorithm(CSA) performs better than the range-Doppler algorithm(RDA) under deep squint angle and large imaging scene by avoiding interpolation. For SAR image formation process, autofocus algorithm is usually necessary, but most current autofocus algorithms are based on RDA. This paper presents an approach to combine the autofocus algorithm with CSA which will be more practical. This paper also suggests a method to combine motion compensation based on moving sensor and autofocus algorithm based on radar data with CSA. This method is very suitable for high resolution airborne SAR.
Flat Earth Removal and Denoising in InSAR Images
Hu Qingdong, Mao Shiyi
1999, 25(4): 402-405.
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Thermal and "Speckle" noise is an obstacle to generate digital elevation model(DEM) from the interferogram by 2-D unwrapping of Interferometric SAR. The boxing and median filters effects on reducing the noise are investigated in detail in this paper. Especially for the single complex images, it is more convenience to process the images by low-pass filters in image domain than in the frequency domain. And the window size effects on the processing are also discussed in detail. In order to process the noise by low pass filter reasonably, the flat earth removal is introduced to eliminate the frequency shift effect arisen from the geometry of the interferometric SAR. At the same time, the interferogram after earth flat removal can show the earth topography directly. The raw data show the validation of the algorithms in the processing.
Studies for System Reaction Time of Phased Array Radar
Yang Chenyang, Mao Shiyi, Li Shaohong
1999, 25(4): 406-409.
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The system reaction time of phased array radar is studied. The formula to compute the reaction time is proposed when TWS and TAS tracking mode are applied in phased array radar. The relationship between the reaction time and the searching, tracking and acquisition mode and their parameters are established. The optimization for the acquisition parameters is studied. The reaction times for the two tracking modes are compared. It is shown by the examples that the reaction time of TWS primly depends on the frame period of search and the target's velocity, and has nothing to do with the number of target. The reaction time of TAS mainly depends on the number and velocity of target, and is little effected by the frame period of searching.
Method of Anti-interference Information Processing based on System with Random Changing Structure
Wu Sentang, Xu Guangfei, Tang Yong
1999, 25(4): 410-413.
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In the complex environment of interference confrontation,to solve the accuracy problem of increasing information processing(for example,tracking problem of maneuvering targets with many sorts of means of interference confrontation). This paper presents a new method of anti-interference information processing based on the system with random changing structure.This method can identify the states of random interference and arrive at a decision about optimization and utilization of system resources(for example,sensor's optimum reconfiguration).This algorithm can reduce the effect of interference on information processing accuracy as a maximum limitation.Simulation for the algorithm's characteristic is conducted.Simulation results proved this method effective.
Application of General Orthogonal Polynomials on Tracking Problem of Time-varying Systems Optimal Control
Wu Bin, Cheng Peng
1999, 25(4): 414-417.
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A new method is presented for solving the tracking problem of time-varying systems optimal control. The approach starts by applying general orthogonal polynomials operational matrices and using finite GOPs expansion to approximate state, control variable and performance index, then differential equation and integration equation convert into algebraic forms, the control problem becomes one of finding the GOPs coefficients of the control variable alone with minimizes the cost function, so the method avoids solving the nonlinear Riccati equation and the calculation procedure become effective and straightforward. An illustrative numerical example is interpreted to support this technique.
Suboptimal Filter Algorithm of Initial Alignment in Inertial Navigation System
Wang Danli, Zhang Hongyue, S.I.Gubarenco
1999, 25(4): 418-421.
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The dynamic error vector equation of the initial alignment in an inertial navigation system and the observability problem of the dynamic error vector are analysed.The system state space is divided into observable subspaces by using the observable degree of the dynamic error vector.In the initial alignment problem of an inertial navigation system, a suboptimal Kalman filter algorithm is constructed by using the concept of the observable degree of a variable.The optimal Kalman filter algorithm and the suboptimal Kalman filter algorithm of the initial alignment are realized by using C language to programming.Simulation results show that the proposed suboptimal Kalman filter algorithm is available to the initial alignment in an inertial navigation system.
Theoretical Analysis for Squeeze Film Damper withElectrohydraulic Active Control
Li Yunhua, Wang Zhanlin
1999, 25(4): 422-425.
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Aiming at the problems existed in rotating machinery using traditional squeeze film damper combined with dynamic pressure bearing, a project of the hybrid oil film bearing composed of dynamic pressure and static pressure with piezoelectric crystal electrohydraulic active control supply orifice hole, i.e., electrohydraulic squeeze film damper(HSFD), is proposed. For this kind electrohydraulic squeeze film damper, the classical Sommerfeld assumption is not held. In order to solve its pressure distribution, a solution method applied to solve the Reynolds equation with hybrid action of static pressure and dynamic pressure is proposed. Based on this, the theoretical analysis for the rotor system to utilizing electrohydraulic squeeze film damper is carried out, on of the theoretical analysis of pressure distribution of this kind of electrohydraulic squeeze film damper is carried out, so the foundation to realize active control is established.
Scheme Analysis of Power-by-wire Airborne Actuation Systems
Qi Xiaoye, Fu Yongling, Wang Zhanlin
1999, 25(4): 426-430.
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An overview is given of various power-by-wire(PBW) airborne actuation systems currently demonstrated, along with descriptions of their mechanism of operation. After discussing advantages and disadvantages of existing PBW actuation systems, two kinds of new PBW actuation systems, the electromotor-pump compound control and the electromotor-pump-valve compound control, are proposed. The experiments of scheme demonstration present that two kinds of PBW actuation systems proposed are feasible and are necessary transitional forms toward all-electric actuation systems. Further improving the performance of each component in the systems will increase the performance of the whole systems.
Adaptive Control of Systems with Unknown Dead-zones
Jing Shaoguang, Song Zishan
1999, 25(4): 431-433.
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Dead-zone nonlinear characteristics are encountered in many physical components of control systems. They are usually unknown and may vary with time. A robust model reference adaptive controller with an adaptive inverse of dead-zone is developed. Based on the parameter match equation of adaptive control, the tracking error of closed loop system and normalized parameter estimate error is given. It is proved that all of the signals in the closed loop are bounded. A missile automatic pilot with the presented adaptive control scheme is simulated. Simulations show the perfect tracking performance of closed loop system.
3-D Numerical Analysis of Axial Skewed Slotted Hub Treatment
Li Ling, Lu Yajun
1999, 25(4): 434-437.
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The 3-D incompressible steady time -averaged N-S equation , K-ε turbulence model equations based on RNG method are applied to calculate the flowfield in the compressor cascade passage with axial skewed slotted hub treatment .By using the method of zonal grids, single grid system with lapped zones which would transfer the flow parameters is established in the course of calculation . The mechanism of extending stability of axial skewed slotted hub treatment and effect on the compressor are elaborated by means of a 3-D viscous numerical simulation. It is revealed that shape parameters of axial skewed slotted hub treatment are main factors which should be paid attention in the design of hub treatment . They strongly affect stable working range of the compressor.The SIMPLE algorithm with non-stagger grid is employed and the question of the pressure oscillating is solved.
Analogous Criteria of Leakage Flow and Heat Transfer in Labyrinth Seals
Yang Huitao Cao Yuzhang
1999, 25(4): 438-441.
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Some criteria analyses were made to investigate the effect of rotating,etc. On leakage flow and heat transfer in labyrinth seals.A series of analogous criteria for experimental simulation were driven from the method of directional unit system.The principle of directional unit system is suggested that the choice and treatment of the unite system in the similarity theory is quite different from those of public unit systems such as SI system or engineering unit system,even though all they must conform to the Gauss's rule of unit system.For the former,the flexibility and the particularity is necessary,because in the similarity theory the particular and actually phenomenon is investigated,and for the directional unit system, the invariance and the universality is necessary,as it is based on possibility of occurrence of all phenomena.Those analogous criteria are proved to be reasonable and practicable by discussion.
Implementation of Elliptic-type Conditional Moment Closure Model to Nonpremixed Turbulent Reacting Flows
Liu Tao, Liu Gang, Fang Ren, XU Kanglie
1999, 25(4): 442-446.
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The conditional moment closure (CMC) formulation considering both molecular and turbulent diffusions is derived and applied to simulate two dimensional nonpremixed turbulent reacting flows. Calculated results show good agreement with experimental ones. Results show that finite Damkohler number makes conditional averaged variables depart from their equilibrium values and the deviation is the maximum near stoichiometric mass fraction. The increasing Damkohler number increases conditional and unconditional mean reaction rates, and makes the conditional mean variable towards equilibrium limit.It is also shown that the reduction of dimensionality may result in certain deviations. For general elliptic-type reaction flow, it is suggested that the CMC formulation accounting for diffusion effect be employed.
Research on Robust Stability of Multiloop　Aeroservoelastic System
Sun Wei, Zou Congqing
1999, 25(4): 447-450.
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Research on a multiinput-multioutput(MIMO) aeroservoelastic (ASE) system was presented on the basis of modern control theory. The small gain theory and minimal singular value theory were applied to the control system which was equipped with the coupled roll and yaw loop. The stability scope of the aeroservoelastic system to resisted the model error was obtained. Both the methods gave the stability criteria respectively and according to the criteria the robust stability(or stability margin) could be defined. As an expression of turbulence the system uncertainty matrix was described. The above two methods result in the same result on the model of an ACT combat airplane.
Experiment Research of New-type Pressure Control Technology on Rapid Train's Cabin
Zhang Xingjuan, Yuan Xiugan, Wang Changhe, Mei Zhiguang
1999, 25(4): 451-453.
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When two rapid trains travel in tunnel or encounter, there will take place enormous pressure wave which makes passengers uncomfortable. In order to release the pressure wave, the new-type pressure control technology which borrow ideas from airplane's cabin pressure control program is analog tested. The test simulation system include simulation cabin, air inlet system, exterior ambient simulation system, indirect pneumatic pressure regulator and data acquisition system. The test content contain the resistance character of pressure regulator, the static test which exterior ambient is in negative pressure and in positive pressure, the dynamic test which the exterior ambient is variable. the result confirms that the computation analysis is correct and demonstrates that the cabin's pressure is the satisfied with the pressure target , also shows that the present technology is practical.
Mathematical Models of Human Thermal Regulation System
Zhao Chaoyi, Yuan Xiugan, Sun Jinbiao
1999, 25(4): 454-457.
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The human thermoregulatory system is introduced in the paper at first. The study status for the mathematical models of human thermal regulation system is surveyed. A comparative review of characteristics of several existing human thermal models is undertaken. The models receiving consideration in this study are NASA's 41-nodes man model, Kuznetz's model, Wissler's model, Werner's model and those developed at Beijing University of Aeronautics and Astronautics. The characteristics compared include anatomical representation, circulatory representation, solution method and dimensionality of the model. Some suggestions have been bring forward for the further developments.
Study of Image Real-time Compression Technique
Cheng Zijing, Zhou Xiaokuan, Zhou Fugen, Wang Fei
1999, 25(4): 458-461.
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An image real-time compression system based on multiple-mode adaptive compression algorithm has been developed .The system comprises several processors working in parallel mode ,and each processor adopts pipeline working pattern ,so the capacity and the data processing speed of the system are adjustable .The ASIC of the processor has been designed and manufactured by using VHDL and FPGA .The peak processing speed of a single processor can reach 100 Mbit/s .The compression rate can be adjusted dynamically and the PSNR of restored image varies from 35dB to 45dB.The system is characterized with low power consumption , small size, low weight.
Study on Effect Tail Clearance Angle in NC Sharpening of Twist Drills
Lü Yanming, Fan Rui, Chen Wuyi, Chen Dingchang
1999, 25(4): 462-466.
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Through studying the flank face geometry of twist drills, a new concept of effect tail clearance angle is proposed. A method for calculating the effect tail clearance angles is given. The relations between grinding parameters and the effect clearance angles are studied.This paper also shows how to use the new concept as a further criterion to arrive at a solution to the conical grinding method for a drill of given specification. The results show that the tail clearance angle is a very important parameter to drills performance, and the sharpening parameters determine the tail clearance angle. Five sharpening parameters have different effect on the tail clearance angle, θ has the most significant influence and the order of the significance of the other four is Cy、σ、ω、Cx.
Design of Flexural Vibration Holder for Vibration Cutting
Zhang Deyuan, Wu Bo, Li Guangjun, Dong Baoli
1999, 25(4): 467-470.
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The resonance frequency and nodal pitch of symmetrical three-step flexural vibration holder have been calculated precisely based on Timoshenko beams theory, and the 3D curved surfaces displaying the variations of the resonance frequency and nodal pitch with the tool holder sizes have been drawn by a computer. It can be from the contour line diagram of these relational surfaces seen that the influence of the length of side beam on the resonance frequency and nodal pitch is larger than the influence of the length of middle beam on that, so a new method to make the nodal pitch of reground tool unchanged by shorting the middle beam has been proposed. The theoretical calculation results show good agreement with the experimental results, the calculating error of resonance frequency and nodal pitch are 3% and 5% , respectively, so that the present method for designing flexural vibration holder is a convenient and accurate method.
Study on Global Construction of B-Spline Surface by Deformable Model
Xi Ping, Jing Ling, Tang Rongxi
1999, 25(4): 471-474.
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The surface modeling techniques in current CAD systems are generally based on the purely mathematical theories of parametrically described geometry. It is very difficult to design interactively fair surfaces which interpolate given data points or boundary curves. Physics-based modeling techniques are based on physical laws. So the deformation has a great similarity to elastic beams and plates, this makes their behavior natural and fair. The designer can simply and intuitively sculpt the local or global shape by adjusting the applied forces, geometric constraints and physical parameters, therefor can mediate the contradictory of local shape manipulation and global fairness as well as convexity. This method has been used in fairing, N-sided patch blending surfaces and joining surfaces.
Peeling Stress Analysis of Honeycomb Sandwich Structure
Guan Shiwei
1999, 25(4): 475-477.
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This work investigated honeycomb sandwich structure with mathematical analysis and experimental verification in order that the deformation of the face-sheet and the stress in the honeycomb-core of honeycomb sandwich structure under peeling load can be obtained. The theory of beam on elastic foundation was applied to the sandwich structure. The formula to compute the deformation of the face-sheet and the distribution of stress in the core was given for sandwich structure under peeling load based on model in which the core was regarded as elastics foundation and the face-sheet beam on the foundation. The conclusion was reached that the method suggested by the work to analyze sandwich structure is feasible, with merits of low quantity of computation, high precision and direct formula.
Material Selection Information Model Study Based on STEP Standard
Jiang Xuefeng, Xiao Ling, Deng Jiati
1999, 25(4): 478-481.
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Material selection information model was established for product lifecycle with STEP standard. The information model gives physical property,machine property,technology property,material price for the reality requirement by material data manual. The paper puts forward material selection ways of different design step. Key part' condition analysis in plan step. Part' environment and strength analysis in initial design step. Materials are examined by strength and technology property analysis in detail design step. The paper puts the ways of technology property and economics evaluation.
Application of Input-output Production Function to Make Production Plan
Zheng Yun, Wei Fajie
1999, 25(4): 482-485.
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The application of input-output production function to make production plan outline and product scheduling of make-to-order enterprises are studied. The manufacturing system is divided into production nodes or process centers. According to the rule of dividing the manufacturing system, the route of each varied productions can be described by the production nodes they pass. The input-output relations among production nodes and the dynamic and stochastic factors existing generally during production processes can be reflected by the model of dynamic & stochastic production function, in order that planners can estimate the stochactic factors which influence the manufacturing time. On the basis mentioned above of , considering the specificity of make-to-order enterprises, the production plan outline is made by the model of static production function, and the product scheduling is made by the model of dynamic & stochastic production function.
Method for Dynamic Modeling of Flexible Manipulators
Bian Yushu, Lu Zhen
1999, 25(4): 486-490.
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A method was presented for establishing the dynamic equation of the flexible multi-link manipulator with flexible joints. Firstly, the simplified models of a flexible joint and a flexible link are described respectively, then based on Kane's method and assumptive modes method, the complete dynamic equation of the flexible manipulator is derived and its recursive formulation is given. On this basis, the influence caused by the link flexibility and joint flexibility on the dynamic response is studied using an example. The results show the dynamic model described in this paper is more similar to the actual flexible manipulator system, and both link flexibility and joint flexibility are important in the flexible manipulator system, therefore their influence should be taken fully into account in the dynamic modeling and control of flexible manipulators.
Method for Vibration Control of Flexible Redundant Manipulators
Bian Yushu, Lu Zhen
1999, 25(4): 491-494.
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For a flexible manipulator, how to eliminate vibration caused by the structural flexibility as soon as possible is very important. In this paper, the theory and strategy of vibration control for flexible redundant manipulators are studied. The idea of active damping control is used to suppress vibration and the corresponding optimal control method is proposed. This method can enhance the damping of the manipulator system by means of optimizing the self-motion of links to input external energy, so as to damp the vibration quickly. Furthermore, the implement of this method is discussed. Finally, with this control method, simulations of the vibration control of a planar three-link manipulator with the last link flexible are carried out. The simulation results demonstrate its feasibility.
Precedence Relation Matrix of Increasing Expansion
Huang Rongying, Wang Zhisen
1999, 25(4): 495-497.
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The processing precedence relation of the dynamic variations in the concurrent process planning is described with the expansion matrix,which forms the generative process of the matrix with the state transformation and the expansion process with the iterative increment.The main algorithm steps are as follows:1.establishing the constraint set, 2.forming the constraint matrix on the basis of the contraint set, 3.generating the expanded line and column vectors of the precedence matrix, and 4.combining the expanded precedence matrix.Thus,a method with intercrossed concurrent and increasingly iterative perfection for the description of precedence relation in the dynamic CAD design has been worked out.

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