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2003 Vol. 29, No. 2

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Reduction of Cabin Noise Induced by Flow Around Air Refueling Pipe
Luo Guailin, Wang Yu, Wang Jinjun
2003, 29(2): 95-98.
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Fixed refueling pipe added to a fighter induces an obvious increase of the cabin noise. In order to reduce the noise, the changing laws of the cabin noise was tested in flight, then the reason of noise increase was investigated by flow field visualization tests and turbulent flow measurements in wind tunnel. After the design of refueling pipe was modified according to the results of present study, the cabin noise was obviously reduced.
Examination of a Computer Vision System Used for the Automatic Landing of Unmanned Helicopter on Ship
Qiu Liwei, Song Zishan, Shen Weiqun
2003, 29(2): 99-102.
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A computer vision solution scheme for the automatic landing of unmanned helicopter on ship was examined from the view of engineering application. A series of computer vision algorithms such as LOG filter, Hough transform and Kalman filter, were adopted and integrated to get the relative positions between the helicopter and ship, from which their relative movement parameters were obtained. Kalman filter were used to reduce most of the noises of position and movement parameters. Computer simulation results indicated that the presented algorithms were robust and reliable.
Optimum Interleaver Design for serial Concatenated Convolutional Codes
Li Yi, Fan Yuezu, Li Daoben, Li Yonghui
2003, 29(2): 103-107.
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Serial Concatenated Convolutional Codes (SCCC) is a better scheme presented recently for channel coding. This scheme employs two recursive systematical convolutional codes and an inner interleaver, where interleaver design plays an important role. According to coding structure and puncturing patterns of SCCC, an "balance protection" pseudo random S interleaver was introduced. Theoretical and simulation results showed that the proposed interleaver performed better than other random interleaver and block interleaver,and provided the design criteria of inner interleaver for SCCC.
Operational Profile Development Based on UML Use Case Diagram and Sequence Diagram Model
Wang Hao, Wu Ji, Liu Chao, Gao Zhongyi
2003, 29(2): 108-111.
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A new approach for developing operational profile used in software reliability engineering was presented, based on UML (Unified Modeling Language) use case diagram and sequence diagram model. With the approach, the operational profile developing process was reduced to three main steps. To compare with Musa's method, a subset of a telephone system was used as an example to demonstrate the ability of our approach to construct operational profile. The result proved that this approach was not only equivalent to Musa's, but also more efficient and more tractable.
Design and Implementation of the Telemetry System for Pilotless Helicopter
Lu Guolei, Zhang Xiaolin, Jin Shi, Kuang Wei
2003, 29(2): 112-115.
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It is very important to maintain a reliable telemetry data communication link between the pilotless helicopter and the telemetry ground station due to the special deployment condition and the high maneuverability of the helicopter.The base station system must be small and light while its reliable functions can meet the use of a mobile telemetry and remote command base station. The design and implementation were discussed for the measuring of the helicopter parameters, the communication link maintaining and the data processing of the telemetry system for the pilotless helicopter. This system has undergone several flight and performance test,and the results showed that stable operation was ensured.
Application of Inductorsyn in Sampled Servo System
Liu Qiang, Er Lianjie, Wu Yunjie, Wang Weihong
2003, 29(2): 116-119.
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For the sampled servo system using inductorsyn as position sensor, the presence of measuring delay leads to large measuring error. In order to solve the problem mentioned above, a new dynamic compensation method using linear extrapolation scheme was presented to compensate the measured output of inductorsyn. Thus the measuring error induced by measuring delay was reduced, and the system tracking precision was enhanced. By theory analysis, the bound of measuring error after error-correction was deduced. The simulation results and the experimental results applied to the three-axis flight motion simulator demonstrate its validity.
Wind Tunnel Test for Roll/Lateral Aeroservoelasticity of Aircraft
Zhang Junjie
2003, 29(2): 120-123.
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The low speed wind tunnel test of a aeroservoelastic (ASE) aircraft model about roll/lateral direction was introduced, in order to validate the analysis method about aircraft ASE stability and stability margin. The test model, subsystem of test, the ways to carry out test, the test content and the test result were discussed. Some techniques, such as the model suspend system, similitude method about control law, hydraulic control system, computer control for test, and data manage were described in detail. The test result can be used in practical aircraft design, and many experiences were obtained. Meanwhile, it is showed that the current ASE analysis method was feasible, but should be modified in further research.
Galvanic Corrosion Behavior between Titanium Alloy and HighStrength Alloys
Liu Jianhua, Wu Hao, Li Songmei, Xie Zhibing
2003, 29(2): 124-127.
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Galvanic corrosion between titanium alloy TC2 and two aluminum alloys (LY12,LC4) and two high-strength steels (30CrMnSiA,1Cr17Ni2) were investigated by galvanic corrosion testing,SEM and DES. The difference of galvanic corrosion behavior of two aluminum alloys and of galvanic corrosion behavior of two high-strength steels were analyzed. On the above basis,the rule of galvanic corrosion between titanium alloy and high-strength alloys was studied. By comparing the galvanic corrosion behavior of aluminum alloys with that of high-strength steels,the relationship between differential value of open circuit potentials and the value of galvanic corrosion current density was discussed. It was concluded that the galvanic couple of 1Cr17Ni2-TC2 can be available, but the galvanic couples of LY12-TC2,LC4-TC2 and 30CrMnSiA-TC2 should be avoided.
Infrared Image Car License Plate Location Method Based on Apriori Knowledge
Hu Aiming, Zhou Xiaokuan
2003, 29(2): 128-131.
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Since the background of a car license plate in an infrared image is quite complex, so it is difficult to locate it. A fast infrared image car license plate automatic location system is presented. The system is suitable for locating the position of car license plate in an infrared image under all-weather condition. Based on the feature of a car license plate image possesing of the highest average gradient in whole image, location system is designed and implemented, andthe accuracy of location rate can reach 99%.
Speckle Filtering Based on Segmentation for Monolook SAR Images
Yan Ying, Zhou Yinqing
2003, 29(2): 132-135.
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A segmentation based method was proposed for speckle-reduction of synthetic aperture radar(SAR) monolook images. Taking explicitly into account the characteristics of areas in a SAR monolook image, this method maximizes a given area with the help of edge detection with constant false alarm rate, and applies optimum filtering in the segmented area. Moreover, edge detection and image segmentation in the multilook image assure the effectiveness of the operations. Comparing with typical speckle filters, experimental results suggest that the proposed filter is an excellent alternative in speckle suppression.
Numerical Evaluation of MagneticDipole Field in Inclined Multilayer Dipping Media
Shi Xiaofeng, Li Zheng, Wang Baofa, Xiao Hongbing
2003, 29(2): 136-139.
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The electromagnetic response of magnetic-dipole in inclined multilayer dipping media was studied. Electromagnetic field formulas and a successive derived numerical method were given. On the above basis, a approach to profile and to predetermine the formation interface using resistivity readings at large dip angle was presented. Numerical simulation and application both proved that the approach is efficient. The present results are suggested to be valuable for application.
Distortion Error Model of Image of Ellipse Center in 3D Visual Inspection
Wei Zhenzhong, Zhang Guangjun
2003, 29(2): 140-143.
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In 3D visual inspection applications, there usually exists a distortion error of the CCD camera's pin-hole image of ellipse center. To address this problem, a mathematical model of this distortion error on the image plane of the CCD camera was established based on the theory of perspective projection and the theory of spatial analytic geometry. As it can quantificationally compensate the distortion error according to the parameters of vision system and the position and geometrical parameters of the inspected object, the proposed model provides a valuable theoretical reference for the inspection of the centers of the circular holes (elliptical holes) or cylindrical (cylindroid) workpieces, for the inspection application of structured-light based 3D vision and for the calibration of the intrinsic parameters of CCD cameras.
Preparation of in Vivo Degradable Material Used in Bone Fixation
Shi Xiaolin, Xie Huaiqin, Zhang Zhenyu
2003, 29(2): 144-146.
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To develop a kind of material with moderale strength and flexibility for bone fixation. First a series of product polymeric on chain reaction was obtained between poly D,L lactide and poly several lactore. Then to detect change regulation which tensile strength and degrading properties of product polymeric following extending chain agent and extending chain reaction condition, extending chain agent was selected and the best technology was formulated. With the above method, the polymeric of bone fixation was made, which is harmless to human body.The tensile strength of this product polymeric is 24.47 MPa, and its breaking elengation ratio is 1091%, to degrade it need six months.
Radar Scattering Characteristic Test and Analysis of Two Stealth Aircraft Models
Zhang Yunfei, Ma Dongli, Wu Zhe, Zhang Kao
2003, 29(2): 147-150.
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Radar scattering characteristics of two stealth fighter models were tested and analyzed. The models were stealed with the following procedures: controlling the radiating directions and numbers of main scatter sources, increasing the occupation ratio, surface metalizing, leaning the intake lips in three directions, and designing the gaps of the aileron as rhombus. The main results and conclusions are as follows: RCS values of both models are less than 1 m2, meaning that the stealth characteristic in nose direction is of great importance to the design of modern fighter. It is of benefit to stealth to reduce the number of scattering directions. Incomplete dihedral reflector constructed with the leaned tailer and wing, fuselage or stabilizer is a strong scattering source.
Image Compression ASIC for Satellite Remote Sensing Application
Cheng Zijing, Zhou Xiaokuan, Jiang Hongxu
2003, 29(2): 151-155.
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A VLSI architecture for the algorithm of combining re-sampling with multi-mode adaptive quantization was proposed. With low hardware complexity and fast computation rate, the architecture can deal with huge amount of data and match the requirement of VLSI architectures in regularity, modularity, locality. Based on the architecture, ASIC for real-time compression application for high resolution satellite remote sensing imagery was designed and manufactured using FPGA(Field Programmable Gate Arrays). An outstanding feature of the ASIC is that it can process one pixel during each clock cycle. At the clock frequency of 36MHz, a peak processing speed as high as 288Mbits/s of the image compression ASIC can be reached, with a power consumption lower than 1W.
Experimental Investigation on Effect of Horizontal Tail Deflectionon Aerodynamic Characteristics of Aircraft under Vectoring Jet
Wang Yankui, Deng Xueying
2003, 29(2): 156-160.
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Thrust vectoring is one of the advanced technologies in the design of 4th generation fighters to provide high maneuverability and agility. The effect of horizontal tail deflection on aerodynamic characteristics of aircraft with or without vectoring jet was investigated experimentally in a FL-1wind tunnel, as a function of testing parameters such as ,δj,α,Ma. Attention was focused on the influence of vectoring jet and the interaction between the vectoring jet and the mainflows around the forebody and afterbody of a modern fighter. It was found that (1) the deflection of the horizontal-tail doesn't affect the static stability of the aircraft with or without vectoring jet except the change of mz0 and α0. (2) Whereas the flow patterns over the wing can be changed greatly, improving the vortices flows and aerodynamic characteristics of the aircraft via the deflection of the horizontal-tail. (3) In addition, vectoring jet can influence the vortex burst flow at high attack angle greatly on the afterbody or extending to the foreboy with 10% increment of the lift.
Nominal Stress Approach for Fatigue Life Estimationunder Corrosive Environment
Wang Zhongbo, Liu Wenting, Jiang Dongbin, He Xiaofan
2003, 29(2): 161-164.
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In order to estimate fatigue life of aircraft structures under corrosive environment, a nominal stress approach under corrosive condition (Cor-NSA) was developed. Based on the curve of parking corrosion influence factor (C) versus parking time (T),p-S-N curves for the critical part of an aircraft component can be determined by inverse computation method, corresponding to different parking years. Thus, the fatigue safe life of aircraft structures under service environment could be predicted according to Miner's law. Furthermore, the life should be modified with flight corrosion influence considered. Finally, an example was given to show the validity of the method.
Numerical Investigation of Pressure Oscillation inGas Dynamic Resonance Tube
An Lian, Liang Guozhu, Tong Xiaoyan
2003, 29(2): 165-168.
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For studying the heating phenomenon in the gas dynamic resonance tube, the two dimensional axisymmetrical Euler equations and the explicit MacCormak scheme were used to simulate the non-stationary flow field in a resonance tube. Calculations were done for the driving gas of different pressures. Pressure oscillating histories and distributions of other flow parameters in the resonance tube were obtained. The calculated results confirm that the inflow and outflow of traveling shock waves and expansion waves by turns in the resonance tube results in the pressure oscillation, and the pressure oscillation is related to the pressure of the driving gas. Agreement of the calculated pressure oscillating curves with experimental results suggests that the employed numerical method is valid in modeling the resonance flow process.
Application of SDMA in GSM
Cui Yan, Lü Shanwei
2003, 29(2): 169-172.
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Considering the special characters of GSM (Globle System for Mobile) and the method presented by other researchers which uses antenna arrays to eliminate the cochannel interferences in wireless communication, a SDMA (Space Division Multiple Access) architecture used in GSM was put forward. Adaptive array and soft beamforming were used in this method to realize SDMA in TDMA (Time Division Multiple Access) system and no estimation of DOA (Direction of Arrival) or spatial signature was required in advance. This method can produce orthogonal beams in relative mild situation, therefore the same channel can be used by different users simultaneously. The applicability of this method was verified through simulation.
Vibration Attenuation Mechanism Investigation of a Adaptive Squeeze Film Damper
Ma Yanhong, Hong Jie, Zhao Fuan
2003, 29(2): 173-177.
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An ASFD/MRR (Adaptive Squeeze Film Damper with Metal Rubber outer-Ring) was designed to improve the high non-linearity of oil film force of conventional SFD (Squeeze Film Damper). The ASFD/MRR can effectively reduce vibration due to its ability of automatically adjusting the film clearance by elastic deformation of the metal rubber. Experimental results indicated that ASFD/MRR can control the clearance of the film and its oil film force characteristics are better than those of SFD. If ASFD/MRR can markedly restrain the occurrence of nonlinear vibration phenomenon such as bistable characteristic, lockup and non-synchronous motion, it can be suitable for wider range of unbalance level.
Design of Radio Frequency Smart Card Module
Yan Guangwen, Zhang Qishan
2003, 29(2): 178-180.
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Based on the ISO14443 and the principles of modern communication, a new method to design RF module of contactless smart card reader presented by using latest RISC single chip microprocessor .Encode and decoder were realized mainly by software instead of hardware ASIC. It has high performance of reliability and its operation distance can reach 10cm, without using high frequency RF power transistor or MOSFET. So it's much more less expensive than all of former RF module.
Disturbance Observer Based Robust Tracking Control of HighPrecision Flight Simulator
Liu Qiang, Er Lianjie
2003, 29(2): 181-184.
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Design method of a robust digital tracking controller based on disturbance observer for high precision flight simulator was presented. The controller consists of feedforward controller, feedback controller and friction compensation term. Feedforward controller composes of a zero phase error tracking controller and a zero phase low pass filter. Feedback controller consists of a proportional derivative controller and a disturbance observer. Columb friction model based fixed compensation was used in friction compensation term. Experimental results demonstrated that the proposed controller can effectively improve tracking performance, with strong robustness against parameter uncertainty and extern disturbance.
Study on Flowing State of Magnetic Fluid in Seal Gap of Reciprocating Shaft
Li Decai, Lan Huiqing, Bai Xiaoxu, Wang Zhishan
2003, 29(2): 185-188.
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In order to solve the problems that exit in the magnetic fluid sealing of reciprocating shaft, the magnetic fluid flow in the seal gap was studied when the reciprocating shaft moves with different velocities and strokes. The follwing were focused on the regular pattern of such flow, the loss quantity of magnetic fluid caused by the reciprocating motion shaft, the failure reasons of this magnetic fluid sealing and the design of a new structure for the magnetic fluid sealing of reciprocating shaft. The application indicates that the new structure is very effective in some occasions.

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