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2004 Vol. 30, No. 09

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UML-based analysis method for collaborative intrusion detection system
Qian Depei, Zhang Ran, Bai Yuebin
2004, 30(09): 803-807.
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To enhance the capability of detecting distributed attacks, a general model of distributed collaborative intrusion detection was proposed, which is based on multi-agent. It achieves detection of complex attacks through coordinating the lower-level agents using coordination agents. Unified modeling language (UML) was employed to analyze and design the main functions and the static structure of the model, the inner reasoning behavior of agents and the cooperating behavior among agents. UML provides an effective means for the analysis and design of collaborative intrusion detection system, which facilitates its integration with other security systems.
Model analysis of bladed disk coupled system of compressor with low aspect ratio
Zhang Dayi, Shi Yajie, Lin Li, Hong Jie
2004, 30(09): 808-812.
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To study the blade vibration in coupled impellers system, a finite element model in the base sector for a coupled impellers system with low aspect ratio in a compressor was created. A vibration analysis for the coupled system by wave transmittal technique was processed, thus computed the coupled vibration that may occur during operation. The special vibration mode of blades with low aspect ration was figured and the relation between frequency of vibration and rotate speed was developed. The special modes of vibration in the impellers system with low aspect ratio and the relation between frequency of vibration and node lines were pointed out.
Reliability analysis based on simulation modular to control system
Wang Shaoping, Tao Jianfeng, Jiao Zongxia
2004, 30(09): 813-817.
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An object-oriented method of computer aided failure mode and effect analysis (CFMEA) was presented. The simulation modular of control system was established, in which the data, performance and mapping relation were encapsulated in component model and typical control modular. Through causal reasoning at attribution between objects, it is easy to transfer the CFMEA results into corresponding fault tree so as to realize the reliability analysis for control system. In the control system modeling, the dynamic performance in reliability model was inducted, its solution method based on simulation was provided. The application results indicate that the reliability analysis based on simulation modular is effective and easy to combine the advantage of system function and performance.
Investigation of testing dynamic characteristics of digital closed-loop fiber optic gyroscope
Wang Yan, Zhang Chunxi
2004, 30(09): 818-821.
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The fiber optic gyroscope is a new rotation sensor, and it is based on the Sagnac effect. The bandwidth of fiber optic gyroscopes is wider than mechanical gyroscopes. It is difficult to test dynamic characteristics of fiber optic gyroscopes with traditional equipment. Considered the principle of digital closed-loop fiber optic gyroscopes, the technique of testing dynamic characteristics was schemed out by means of adding signal to integrated optic modulator. The phase difference due to rotation rate was replaced with the phase difference generated by ramp phase modulation. Based on system transfer function, equivalence of the technique was proved. Step response and frequency response were tested. The conclusion that the bandwidth of FOG exceeded 2 kHz was approved.
Electromagnetic characteristics of different shape ZnO composite
Liu Jianhua, Sun Jie, Li Songmei, Chen Dongmei
2004, 30(09): 822-825.
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Tetrapod-shaped ZnO whiskers (T-ZnO) with the structure of hexagonal cross sections were prepared by using the control method of carbon-reducing agent. The spherical-shaped ZnO nanocrystals were synthesized by using stearic acidsol-gel combustion technique. The dielectric constants and magnetic constants of the products were studied by using the waveguide method of electromagnetic characteristics. It was shown that the increments of both dielectric loss and magnetic loss of tetrapod-shaped ZnO (T-ZnO) whiskers and the ZnO nanocrystals were not obvious with the frequency in the range of 8~12 GHz. It was demonstrated that the tetrapod-shaped ZnO (T-ZnO) whiskers and the ZnO nanocrystals were the materials with the performance of dielectric dissipation by the experiment of microwave electromagnetic characteristics, and the dielectric dissipation of T-ZnO was higher than that of nanosized ZnO. It was not found that the bulk materials of ZnO had the electromagnetic dissipation performance in the range of frequency 8~12 GHz.
High resolution spaceborne SAR implementation method based on multiple phase centres antenna
Liang Weibin, Li Chunsheng, Zhou Yinqing
2004, 30(09): 826-830.
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An implementation method of high resolution spaceborne SAR based on multiple phase centres(MPC) antenna was studied, especially to the tri-phase centers antenna, as can effectively resolve the impact of resolution and swath extension. The echo signal model was proposed, and a method of processing the echo signal was discussed. In this method, the echo was transformed to the standard echo as usual one phase central antenna, which can be processed by traditional strip-mode imaging algorithm. The PRF departure’s influence on imaging performance was also deeply studied and the false target’s position and relative magnitude was given. The result of computer simulation proves the validity of the content.
Numerical study on hydrazine arcjet thruster working exchangeability
Xiao Yingchao, Tang Haibin, Liu Yu
2004, 30(09): 831-834.
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A simplified physical model of an arcjet thruster was established on the basis of proper understanding of the physical mechanism of its working course, and a mathematical model for it was expressed by using Navier-Stokes equations coupled with electromagnetic source terms based upon the physical model. Calculation for working performance of a low power hydrazine arcjet thruster with arc and without arc was achieved comparatively. Second-order-accuracy non-oscillatory and non-free-parameters dissipative finite difference scheme and explicit time-marching method were used to obtain numerical solutions. The computationalresults present flow configurations within the thruster with arc and without arc, foretell its thrust and specific impulse in various conditions, and attest its working exchangeability.
Study on an XML approximately duplicated data cleaning method
Chen Wei, Ding Qiulin
2004, 30(09): 835-838.
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Aiming at the importance of semi-structured data XML in data cleaning, how to clean XML approximately duplicated data was studied. An efficient XML approximately duplicated data cleaning method was proposed. This method is adaptive, because any other approximately detecting algorithm can be used in it. An efficient approximately detecting algorithm based on tree edit distance was presented. This algorithm can detect approximately duplicated data efficiently. The lower and upper bounds of tree edit distance were used to optimize the approximately duplicated data detecting algorithm. The improved algorithm can avoid computing the tree edit distance that is not needed between a pair of XML data, and reduce the approximate computation complexity. So, foundations are built for researching XML approximately duplicated data cleaning.
Ambiguity performance analysis of spaceborne SAR with thermal mechanism errors in phased array antenna
Chen Jie, Zhou Yinqing
2004, 30(09): 839-843.
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To analyze the ambiguity performance of spaceborne synthetic aperture radar (SAR) with onboard thermal mechanism errors in phased array antenna, a mathematical model for thermal mechanism errors was established, based on the characteristics of spaceborne SAR antenna. The formula of the antenna pattern with thermal mechanism errors were presented, on the basis of paired echo distortion theory. The statistical model for ambiguity performance analysis of thermal mechanism errors in phased array antenna was proposed. The maximum boundary of ambiguity performance requirement was educed. The computer simulation results of a L-band spaceborne SAR was proposed, by which the conclusion was validated.
Error analysis based on hierarchical availability analysis
Wang Shaoping, Tao Jianfeng, Jiao Zongxia
2004, 30(09): 844-849.
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With the hierarchical decomposition technology, the dynamic fault tree of complex system can be simplified into individual modular, which assumes that there is no intrinsic relation with other modulars. The equivalent time-variable availability parameters of individual modular such as equivalent failure rate and equivalent repair rate were deduced, the system availability can be obtained through recursive algorithm with equivalent availability parameters from bottom to up. Actually, the hierarchical availability analysis method exist some errors comparing with availability analysis based on whole states due to the hierarchical decomposition. The cause of error formation because of failure dependence and repair dependence was analyzed, the error definition in different situation was investigated and the error distribution field was calculated. The suitable condition and application principle were presented to improve the modeling error of hierarchical availability analysis. The application indicates that error analysis of hierarchical availability analysis is helpful to reliability analysis of complex system.
Error analysis of a computer-assisted orthopedic system for distal locking of intramedullary nail
Liu Wenyong, Wang Manyi, Wang Tianmiao, Hu Lei
2004, 30(09): 850-854.
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To solve the distal locking difficulty arising from the bending and twisting of the intramedullary nail axis while the nail implanting in long bone fracture therapy, an image-guided computer-assisted orthopaedic surgery system was introduced. To evaluate the error distribution of the system, a special error analysis method was designed based on the character of the system structure and its geometric model. The concrete calculation and statistics of error distribution were embodied with the assistance of the Monte-Carlo method. The system performance was also evaluated in order to derive the theoretic guarantees for further optimizing the system. The idea of this error analysis method can be used for the similar systems with complicated mathematical models.
Optimal design of composite sandwich structure
Xiu Yingshu, Cui Degang
2004, 30(09): 855-858.
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The aeroelastic property of a wing can be improved by using the bending-twisting coupling effect of composite material skin. A genetic algorithm approach was employed to optimize this type structure in order to maximize the effect of bending twisting coupling and a sandwich structure to be an analysis example. A finite element software was used to analysis the objective function, the strength of the sandwich structure were used as the restriction function. The genetic algorithms optimum and finite element analysis function were integrated so that a structure optimal software was developed for complex structure optimization.
RLS de-spread re-spread multitarget array algorithm for MC-CDMA
Wang Huimin, Lü Shanwei, Su Donglin, Han Yanju
2004, 30(09): 859-862.
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Multi-carrier code division multiple access(MC-CDMA) is a hybrid of orthogonal frequency division multiplexing(OFDM)and code division multiple access(CDMA).To resist co-interference of MC-CDMA system,smart antenna are used in MC-CDMA. A blind adaptive array algorithm was developed for MC-CDMA system by using recursive least-squares dispread respread multitarget array. The proposed algorithm without training sequence for adaptive beamforming doesn't waste extra-spectrum by utilizing information of CDMA spreading codes. Compared with the RLS-DRMTA,the extended RLS-DRMTA algorithm proposed is less computation-consuming. The high performance of the system is achieved by post-FFT beamforming. Subcarrier clustering is applied to reduce the complexity. But subcarrier clustering reduce the performance of the system .So the complexity and the performance of the system are considered in clustering subcarrier. The results of simulations can be shown by the RLS-DRMTA algorithm that the array focuses energy in the required direction,which helps to reduce the interference.
Numerical calculation of stretch bending of narrow strip and analysis on spring back
Du Song, Anatoly, Chumadin
2004, 30(09): 863-867.
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To analyse stretch bending of narrow strip by numerical calculation, taking the loading history into account, the deformed zone was divided intomany elements to determine their strain by the condition that constant volume remains in deformation. Increment strain theory was applied to calculating the stress distribution from difference equation and the effect of loading history on them was discussed. The formulae for calculating the bend radius of neutral plane and the decrement of bend angle after springback were derived by considering the deformation after unloading. The simulative results show that stress distribution under stretching with superimposed bending is more advantageous to the reduction of spring back.
Research on fault diagnosis and running with fault method in dynamic system based on PLC
Gao Shumin, Fei Yuhua
2004, 30(09): 868-871.
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The fundamental and means of realization of fault diagnosis was introduced, which can be applied in the dynamic system controlled by PLC controller. In order to improve the reliability of the control system, one method that is realized by programming the ladder diagram to make use of the output module to shield the exception points was presented, which can realize fault detection and tolerance control function in the running process of the dynamic control system and can be even enable the system to run with fault. The applied instance illustrated that the method is very feasible in avoiding or reducing the fault effect on system.
Design and realization of GPS/GLONASS positioning emulator
Song Changfeng, Teng Jitao, Wang Y, ong
2004, 30(09): 872-875.
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GPS(global positioning system) and GLONASS(global navigation satellite system) which are two kinds of real time satellite positioning systems are applied widely. In order to fit the needs of offline experiment, a GPS/GLONASS positioning emulator that based on the theory of satellite navigation was designed. This emulator analysed the movements of satellite constellation, simulated the calculation of satellite receivers, and realized satellite positioning in pure software mode. The simulative calculation results show that its accuracy is identical to that of real receiver on the whole. So the emulator can simulate real satellite positioning, and makes the simulation works convenience.
Body fitted method with cartesian coordinates for solving viscous fluid flow and heat transfer problems
Kang Ning, Wang Jianbing
2004, 30(09): 876-881.
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A body fitted unstructured numerical method which takes advantage of Cartesian coordinates and reserves irregular control volumes near boundaries was studied for solving incompressible viscous fluid flow and heat transfer problems. The conservation equations were solved in the cells that are intersected by the wall according to the traditional methods without interpolation and are discretized using collocated grids with all discreted dependent variables located at common nodes throughout domain. This scheme is body fitted method which is well suited to simulating fluid flow and heat transfer problems on general complex boundaries. To test the accuracy of this approach, it was applied to two benchmark cases: flow between two coaxial cylinders’ surfaces; flow in a 2-D inclined driven cavity. Agreement was found with analytical, numerical benchmark and STAR-CD results. All these show that this method is validated for fluid flow and heat transfer problems.
Temperature prediction and simulation model of satellite’s thermal balance test
Li Yunze, Wang Jun
2004, 30(09): 882-884.
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To predicate the equilibrium temperature and simulate the heat variation influence of satellite thermal balance test more easily and correctly, a double layer lumped parameter model of the satellite equipment temperature was set up. The dynamic model had a simple nesting structure, its parameters can be reached from thermal balance test datum by using system identification method, and the temperature changes of different equipments on same satellite can be predicated and simulated separately, this can save a lot of computing works. Comparison studies show that the prediction and simulation results accord with the satellite thermal balance test results of accurately.
3D numerical analysis for the effect between tip clearance and casing treatment in turbomachinery
Yuan Wei, Zhou Sheng, Lu Yajun
2004, 30(09): 885-888.
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The field in tip clearance of some compressor stator was simulated by Numeca CFD, as well the field in casing treatment slots. The results were compared and analyzed, the computation showed detail streamline in tip clearance and slots. By the casing treatment, the flow path was changed, the tip leakage eddy can be passed through, so the blockage of low incline streamline can be moderated. The field near the tip enterd into the inclined slots by the high pressure from the tailing pressure side, then jet into field near the leading suction side. The jet fluid sweeped off the stalled flow, so the flow separated was postponed, and the stable operating flow range was increased, and the quadratic flow loss was decreased. The high jet effect on main flow from momentum exchange may be primary reason that slot casing improved the stable operating range.
Human-imitating control based on chaotic neural networks
Shi Xiaorong, Zhang Minglian
2004, 30(09): 889-892.
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A control method was proposed, which combines the human-imitating control theory and the optimization capability of chaotic neural networks (CNN). Firstly, a qualitative control law(linear or nonlinear control law)was formed according to human-imitating control. Then, the qualitative control law was quantified by CNN. Hopfield neural network is recognized as a useful tool for optimization problems. However, it is often trapped to a local minimum solution. Therefore, gradually reducing chaotic noise is added to the networks to form a powerful globe optimization algorithm. Applying the proposed control method to a double inverted pendulum, the results of numerical simulations and experiments both demonstrate the valid of this control method.
Research of task assignment in aircraft utility management system
Ma Baohai, Qiu Lihua
2004, 30(09): 893-896.
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The airborne utility management system is the inevitable developing trend of airborne system. The tasks of the airborne utility management system were partitioned for solving the task assignment problem. The two-level tasks allocation strategy of cycle tasks and un-cycle tasks was put forward because their contributions are difference for the risk coefficient of system. Taking the balance of risk coefficient among the computers as the goal function, the cycle task allocation arithmetic based on the ant colony optimization arithmetic was designed. The ant colony arithmetic was improved by fuzzy-adaptive parameter regulation. The simulative results show that the improved arithmetic can efficiently make it escaped from the local extremum and resolve the UMS task assignment problem of utility management system.
Three-parameter Weibull process of using position element and point estimation
Xiao Lianghua, Zhao Yu, Huang Min
2004, 30(09): 897-900.
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In the Weibull process, the peril rate is zero or infinite when time equals zero. In order to solve this problem of fitting in the engineering, the position element was put forward to revise the Weibull process. Iterative fitting, correlation coefficients method and maximum likelihood method were integrated to obtain the estimations of the scale, shape and position elements in the Weibull process. And meanwhile, some relative reliable characteristics were also estimated. An application example shows the estimations of these parameters can satisfied the requirements by using of this method, when repairable system is fitted by three-parameter Weibull process in the engineering.
Modeling, equilibrium and stability for double balloon system with tether and net
Du Liang, Hong Guanxin
2004, 30(09): 901-904.
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To study the design problem and evaluate the resisting wind ability for a double balloon system with tether and net, the mathematical model of the system was established consider of the effect of wind, it includes the balloon’s mathematical model in the body-coordinate system, tether’s mathematical model based on non-limit analyze theory and the net’s mathematical model according as some assumptions. The nonlinear equations was linearized based on small disturbance assumption in the state of equilibrium. The response and stability of the double balloon system was analyzed with step wind input. The simulative results show that the design of the double balloon system is reasonable and the system is considerable for resisting wind.
Center of gravity estimation in an object oriented aircraft conceptual design system
Liu Hu, Lu Xinlai, Wang Liang, Wu Zhe
2004, 30(09): 905-908.
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In order to evaluate such characteristics as weight and static stability of proposed concepts effectively and conveniently during aircraft conceptual design, the implementation of center of gravity and associated weight estimation in an computer aided aircraft conceptual design system, whose data organization is object oriented, was studied. The emphases were placed on the object oriented structure of center of gravity estimation and methods adopted in this part, especially the methods of estimating center of gravities of fuel and landing gear based on the design and modeling of relevant components. Through conducting weight and center of gravity estimation during the process of dynamic adjustment of concepts, the adaptability and reliability of this part, as well as the flexibility of designers’ interactive controls on estimation, were validated.
Research on airborne power-by-wire integrated electrical actuation and control systems
Sha Nansheng, Li Jun
2004, 30(09): 909-912.
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The development of airborne integrated electrical actuation systems in the latest ten years and main results were summed up. It concluded the virtues of integrated electrically actuation system. The successful airborne electrical actuators consist of electro-hydrostatic actuator and electro-mechanic actuator. It summarized series results referring the electrical actuators which will apply to aircrafts in the future. It presented the key technologies of power-by-wire (PBW) electrically powered actuation systems including high performance hard magnetic material, brushless DC motor-pump, integrated designing and manufacturing, redundancy management, fast response and high precision control. It pointed out the R&D targets and the urgent need technique difficulties to develop the next generation airborne actuation system.

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