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2003 Vol. 29, No. 6

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Experimental Investigation into Effects of Gurney Flaps on Supercritical Airfoil
Li Yachen, Wang Jinjun, Fan Jianchao, Zhang Lin
2003, 29(6): 471-474.
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An experimental study was performed on a supercritical airfoil in the FL-21 wind tunnel to investigate the lift-enhancement effects of the Gurney flaps at high speed conditions. The 0.5%C, 1.0%C, 1.5%C and 2.0%C height Gurney flap increased the maximum lift-coefficient by 6.0%, 12.4%, 21.7% and 22.3% separately, and the 1.5%C height Gurney flap increased the maximum lift-to-drag ratio by 33.2%. The mechanism of this increment in lift is that the pressure upstream of the Gurney flap was increased and the base suction downstream of it was increased also, and this difference in pressure led to an increment in circulation.
Aerodynamic Characteristic Study of Axial Transonic Highly LoadedContraRotating Turbine
Fang Xiangjun, Liu Siyong, Wang Ping
2003, 29(6): 475-479.
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Axial contra-rotating turbine(CRT) comparing with the conventional one has a series of advantages, such as more significant stage efficiency, lighter weight, shorter axial size and less components and so on, due mainly to elimination of stationary vanes. Mainly,CRT basic aerodynamic status was analyed, its formula of efficiency was deduced. The parameters' conditionality relation of both high and low pressure rotors each other to be decreased a free design parameter was expounded. The results show that the high pressure turbine has both very high loading coefficient and large turning angle after the design parameters are adjusted to distribute reasonably the rim power of the high and low pressure rotors, its dynamic characteristic parameters are by far higher than the ones of the conventional turbine.
Anticollision Technology of Type A Cards Based on FiniteState Automata
Zhang Dawei, Zhang Qishan
2003, 29(6): 480-483.
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Based on the basic anticollision theory of Type A contactless smart cards, arithmetic description and state transition of bit collision detection protocol algorithm on cards were designed by finite state automata model. Anticollision procedures on cards were described with the virtue of a state diagram of UML. At last, anticollision protocol was implemented on cards. Practical application shows that this design model is correct.
Analysis of Spaceborne Spotlight SAR Antenna Beam Point Steering
Wang Guodong, Zhou Yinqing, Li Chunsheng
2003, 29(6): 484-488.
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In the condition of beam point steering, spaceborne spotlight SAR antenna model and imaging model were found. The math analysis confirmed that beam point steering resulted in echo amplitude being modulated and caused infinite pairs of echoes. So beam point steering would deteriorate image quality. Besides, based on the analyses of tradeoff relation of beam point steering ratio, imaging area azimuth width and image dynamic extent, the fundamental principle of designing beam point steering ratio was presented. Finally, point target simulation was given and simulation result shows the validity of theoretical analysis.
Study on Technique of Fast Acquisition Pseudo Noise Code in GPS Receiver
Xue Wenfang, Shao Dingrong, Li Shujian
2003, 29(6): 489-492.
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In order to reduce the time of acquisition pseudo noise code in GPS receiver, the conventional acquisition method slide correlation in the time domain was analyzed. The searching range of pseudo noise code was narrowed utilizing to the information provided by epicheirema. The lost reacquisition time was shortened. The fast acquisition technique using FFT was analyzed. Simulation shows that the acquisition speed can be improved obviously.
Synthesis and Performance of Macroporous Anion Exchange Resin
Su Yuqin, Zhang Zuoguang
2003, 29(6): 493-496.
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Ion exchange method is one of the important technologies for abstracting metal from ore. The synthesis of a new macroporous anion exchange resin with two of weak-base functional groups for extracting gold from cyaniding pulp was presented.The effects of resin crosslinking and aminating condition on its performance for extracting gold were studied .The exchange capacity of the resin for gold was determined to be 16 mg/g dry resin and the selective coefficient for gold was 1.1. The performance of this new macroporous anion exchange resin is better then that made in Russia and can be widely used metallurgy industry.
Analysis of Operational Effectiveness for Multiple Fake TargetsCajolery Antagonizing ARM
Ma Dongli, Zheng Mingqiang, Xia Haiting
2003, 29(6): 497-500.
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The operational effectiveness of antagonizing ARM using multiple fake targets to protect a true one was investigated. Having established the aiming direction of an ARM, a method of computing the capture probability of the true and the fake targets was presented when seeker differentiates targets. A universal formula for computing killed probability of the true targets under the attacks of ARM time after time was educed. The results show that the influence of accumulation of targets loss must be considered when evaluating operational effectiveness for fake targets antagonizing ARM and their vulnerability should be reduced, their eradiation power should be improved, and reasonable configuration should be adopted when the number of fake targets is increased to improve the operational effectiveness.
Developments and Evolutions of ThreeDimensional Perturbations inTransitional Boundary Layer
Guo Hui, Lian Qixiang, Yury S. Kachanov, Vladimir I. Borodulin
2003, 29(6): 501-504.
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Formations and developments of typical 3-D perturbations, typically shown as Λ structures, hairpin vortices and ring-like vortices, were observed by means of hydrogen-bubble method in a transitional flat-plate boundary-layer excited by a modulated 2-D artificial perturbation. Visual results show the relationships between a hairpin vortex and a spike structure, which convince the forming mechanisms of spike structures. Dark spots, often detected in turbulent boundary layer, are also observed during flow breakdown, and results show that the instability of local high-shear layer caused by dark spots is probably responsible for flow breakdown.
Lossless Image Compression Based on Feature of Local Texture
Jiang Hongxu, Zhou Xiaokuan
2003, 29(6): 505-508.
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Local texture was the basic element of recognizing the whole image and starting with analysis of local texture was a reasonable way in developing better decorrelation model. Based on this idea, a new lossless image data compression algorithm named lossless image compression based on feature of local texture (FOLT) was presented. The algorithm was composed from two parts, decorrelation and entropy coding. Decorrelation was based on adaptively selection best decorrelating model suitable for the processed local area from a given model group. And the CCSDS adaptive entropy coder was used for entropy coding. The compression results not only show that the performance of the proposed algorithm is better than that of JPEG-LS,but also show the proposed decorrelation idea is effective.
Study of Stability for Strapdown Antenna Platform
Zhou Ruiqing, Lü Shanwei, Liu Xinhua
2003, 29(6): 509-511.
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The strapdown stabilization model for imaging presented by Rudin was applied to antenna stabilized platform. Based on invariance principle, matching filter was used to stabilize antenna platform. The results show that decoupling precision is increased 35 dB at frequency 0.5 Hz~1.0 Hz. The impact of sensor noise on stabilization error also was simulated. Simulating results show that filter is practical in eliminating noise, and stabilization error can be reduced almost 50%. The technique used and results obtained are instructive for engineering problems.
Studies of a Caret Inlet at Subsonic Speeds
Zhu Yu, Li Chunxuan, Li Tian
2003, 29(6): 512-515.
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A Caret inlet was studied by means of experiment and numerical simulation. Basic aerodynamic characteristics of the inlet at low and subsonic speeds were presented. The experimental as well as computational results revealed that flow separations may exist at match state of inlet/engine at low speeds due to the existence of large mass flow rate coefficients. It was the true mechanism causing the low total pressure recovery in the inlet as demonstrated. Experimental results show a low total pressure region being taken place at the upper left corner of the duct exit, which is matched with the results obtained by numerical computations showing that flow separations on set occurs at the low-outboard corner of inlet entrance and develop with no circumrotation.
Ground Experimental Modeling of the Oxygen Supply System'sDynamic Performance Under Explosive Decompression
Sun Bing, Yuan Xiugan, Zhao Yingchun
2003, 29(6): 516-520.
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Ground experimental method of modeling the oxygen supply's dynamic performance under explosive was presented. The comparisons of ground and explosive decompression cabin test results show that the dynamic profiles of pressure have good agreement, and there is a ratio between the pressure release times of them, which suggest that this method can be applied to the dynamic performance research of oxygen supply system under explosive decompression.
Implementation of Network Interface Unit Based on HLA
Wang Huixia, Zhang Yuhong, Wang Xingren, Lin Xin
2003, 29(6): 521-524.
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To study how to transit the existed simulation systems based on distributed interactive simulation (DIS) standard to high level architecture (HLA) and how to develop a new system based on HLA, taking a blue sub-system of distributed virtual battlefield environment as study background, network interface unit(NIU) was adopted to guarantee the interaction between blue sub-system with other sub-systems, adhering to HLA standard. The configuration of the blue sub-system and the function of NIU was introduced.The development of application system based on HLA were described, especially the development and implement of NIU. This method has been used in a virtual battlefield environment, it proved to be effective.
TurboTCM Scheme for Digital Video Broadcast Systems
Ren Juntao, Shao Dingrong
2003, 29(6): 525-528.
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It was presented that Turbo trellis coded modulation (Turbo-TCM) scheme and the corresponding decoding algorithm for the system of digital video broadcast (DVB) system where the code rate of the inner error-correcting code was variable. The proposed TTCM scheme employs a simple rate 1/3 binary turbo code, punctured to achieve higher rates. Various code rates and modulation types had been simulated. The proposed turbo trellis coded modulation provides 1~3dB coding gain compared to the convolutional trellis coded modulation scheme used in the European digital video broadcasting standard(ETSI EN 300 744).
Dual Linera Programming Approach for Parameter Uncertainty Interval Estimation
Sun Xianfang, Teng Jitao, Fan Yuezu
2003, 29(6): 529-533.
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The parameter uncertainty interval estimation (PIE) problem was transferred into a set of dual linear programming (DLP) problems, and an improved simplex method was proposed to solve these DLP problems. The dual relationship between the variables of the DLP problems was used to directly compute an initial basic feasible solution, so that the process of finding an initial basic feasible solution is removed. Moreover, the largest reduction rule was used in the determination of both entering and leaving variables, and thus the iterative number was reduced. Considering that all the DLP problems derived from a PIE problem have the same objective function and constraint matrix, a unified simplex method was given to solve all the DLP problems in a single searching procedure. Simulation results show the effectiveness of the proposed algorithm.
Application of RoleBased Access Control in Management Information System
Li Jian, Tang Wenzhong, Song Changfu
2003, 29(6): 534-538.
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Role based access control was being paid more and more attention as a security mechanism. Traditional access control policies, including discretionary access control (DAC) as well as mandatory access control (MAC), were first briefly introduced. An access control model based on RBAC2 was provided, which not only inherited the advantage of RBAC2, but also extended the ability of modifying individual permissions. An example application of the model is presented as a proof of its availability. The distributed management for permissions was discussed.
Environmental Impact Assessment of Vibration Induced by Pile Sinking
Xia Chuanyong, Yao Yangping, Luo Ting
2003, 29(6): 539-543.
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The features and the environmental impact of vibration induced by pile sinking, recognizing the importance of environmental impact assessment of vibration induced by pile sinking were discussed. It also analysed and explained assessment range, standards, grade, content and investigation of present state, measurement and prediction on environmental vibration in the standard. Especially, the prediction methods for environmental vibration and the plans for preventing environmental vibration was recommended.
Real Time Simulation Research of ExtraVehicular Activity Control Technique
Han Chao, Liu Zhiqiang
2003, 29(6): 544-547.
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The attitude control of extra-vehicular activity (EVA) is a nonlinear and time variant control system with the uncertain parameters. It is difficult for general control method to deal with attitude control of EVA. For validating the disposal of adaptive control method for the problem and engineering practicability of this method, a half-physical simulated system based on DSPACE environment was established. This system ould simulate reality environment and gave out reliable result. Consequently it show that adaptive control method is of good control quality for EVA.
Optical Flow Computation Based on Analytic Wavelet
Tian Tian, Zhou Bing, Li Bo
2003, 29(6): 548-551.
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As two major limitations to applying optical flow to motion estimation, oscillating of wavelet coefficients and cumulative error highly affected precision in calculation. It was proposed that an algorithm for estimating optical flow based on analytic wavelets that suppress the oscillating of wavelet coefficients,and M-estimator that minimizes error of estimation. Experimental resultsshow the applicability of the proposed methods to some benchmark image sequences.
Relationships for the Relative Motion of a Tensor Described in Any Two Rotational Reference Frame
Xing Xiaolan, Chen Wanchun, Yin Jian
2003, 29(6): 552-555.
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The definitions of the relative derivatives of a tensor with respect to time in any reference frame by using the notation of vectrix were proposed. It was shown that with the help of vectrix one can treat the relative derivatives of a tensor more clearly and more rigorously when multiple reference frames were concerned. With the help of the notation of the skew-symmetric tensor,the expression for the 1st order absolute and relative derivatives of a tensor was presented, and the expression for the 2nd order absolute and relative derivatives of a tensor was offered further. When motion was necessarily described in two rotational reference frames, because the specific property of a tensor, although the composition of its "velocity" and the composition of its "acceleration" were similar to that of a vector to some extent in the form of expressions, there were still exists great distinction between them. As a result, the composition theories for the "velocity" and "acceleration" of a tensor were proposed, and they were further extended to the case of the relationships of motion between any two rotational reference frames.
Research on Control Problem and Controller of Parallel Robot
Yin Xufeng, Huan Ji
2003, 29(6): 556-560.
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The inverse kinematics problem and direct kinematics problem of a six branches parallel robot were studied. Their realizing technologies based on open CNC system, especially the real-time coordinate transformation based on the IKP algorithm and the system initialization based on the DKP algorithm were settled. The interfaces between these modules and NC kernel were given. Finally, a controller based on an open CNC system has been successfully developed to control the parallel robot. It can be concluded that using open CNC system and proper interface technologies, real-time control to a parallel robot can be realized.
Property Estimation of Compound Armors by Small Sample Statistic Analysis
Zhang Zuoguang, Shen Jianming, Li Min, Sun Zhijie
2003, 29(6): 561-564.
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The critical non-penetrating area density under different non-penetrating probability and the critical penetrating velocity under different penetrating probability for different compound structure armors with a definite confidence level were presented by small sample two-dimension up and down method based onmany ballistic tests. The statistic analysis on experimental data of three kinds of compound armors was put forward and the critical penetrating velocity, smallest full penetrating velocity and largest non-penetrating velocity with a definite confidence level of each compound armor were revealed. The ballistic performance dispensability of different compound structure armor was analyzed. The results are helpful to the design and application of compound armors.

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