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2005 Vol. 31, No. 11

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High precision fiber optic gyroscope based on Er-doped superfluorescent fiber source
Yang Yuanhong, Wang Zheng, Yi Xiaosu, Zhang Weixu
2005, 31(11): 1159-1162.
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For high precision fiber optic gyroscope application, high performance Er-doped superfluorescent fiber source was demonstrated and a practical prototype with 2.58×10-6℃ mean wavelength stability and less than 1% output power instability within -40℃~+60℃ was made with a cut-off type thin film filter which reflect long wavelength light within 1 550 nm band and the optimal parameters obtained by simulating. The source relative intensity noise was measured and analysed. A close loop all digital fiber optic gyroscope prototype was made using this source. With a noise subtracting technology, the noise in fiber optic gyroscope was reduced and the random walk coefficient decreased about 20% .The whole performance of this gyroscope prototype was tested and the bias drift of the fiber optic gyroscope prototype is 0.004 5(°)/h and the random walk coefficient is 0.003 5(°)/h 1 2 according to the result of Allan variance analysis and its scale factor error is less than 11×10-6. This is satisfied the demand of land inertial system.
Research on motor-driven reverse bootstrap air cycle refrigerating system used on aircraft pod
Xiao Xiaojing, Yuan Xiugan
2005, 31(11): 1163-1167.
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Refrigerating system used on aircraft can provide refrigeration for electronic equipments. Because of the special characters of aircraft pod, there are many differences on framework and working theory between refrigerating system used on aircraft pod and the one used on normal aircraft. Several air cycle refrigerating schemes designed for aircraft pod were introduced. Design concepts, working theories of a reverse bootstrap air cycle refrigerating system driven by 2kW-powered high-speed electric machine were described. Component structural design methods were discussed. Refrigerating performance and performance penalty calculations were given. The results show that the new system has a compact structure and low power consumption. It works reliably and can increase the refrigerating performance. This system is affected by aircraft flight states lightly and can provide cooling capacity when the aircraft is on the ground. It's a promising environmental control system for aircraft pod.
Simulation on cooling system and fuzzy control of BEPC’s beam pipe
Ning Xianwen, Pang Liping, Wang Jun
2005, 31(11): 1168-1171.
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A lot of synchronous radiate heat is generated when beijing electron positron collider operating. The heat is dissipated by the beam pipe’s cooling system. According to the key problem of cooling the beam pipe, an active cooling system based on modular form was developed. In order to investigate the cooling system, a dynamic model was established and flow characteristics equations were derived from parallel regulator valves, by means of lumped parameter method with physical analysis and logical simplification. A fuzzy control strategy was offered and simulated according to the model. Simulation results indicate that the cooling system with fuzzy controller can satisfy the system design demands. It is demonstrated that the fuzzy control strategy is more stable and less overshoot than conventional proportional-integral-differential control strategy. The results can also instruct the engineering design.
One method solving parameter estimation of varying stress accelerated life test
Yuan Zhongkui, Wang Shaoping
2005, 31(11): 1172-1176.
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The maximum likelihood function of varying stress accelerated life is a nonlinear multi-dimension complex object function with five evaluated parameters, whose parameter estimation is easy to get into local optimization with grads descending algorithm while has low searching efficiency with global optimal algorithm. To solve the bottleneck between direct and intellective optimization of multi-dimension complex object function, the genetic accelerated algorithm was presented based on real code genetic algorithm and Powell method. Through designing perfect switch with adaptive function, the genetic accelerated algorithm takes the advantages both genetic algorithm and Powell method at furthest that ensure global optimization and keep rapid searching velocity to multi-dimension complex object function. Application of hydraulic pump on accelerated life test shows that the genetic accelerated algorithm was able to fulfill global optimization at the beginning of parameter evaluation process and approach optimal values rapidly at the end of the process, its success rate of optimization can reach 85%.
New algorithm for constrained control direct allocation
Li Weiqi, Wei Chen, Chen Zongji
2005, 31(11): 1177-1180.
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A new algorithm for the direct allocation method named "adjacent facets searching algorithm "was presented to solving the three-objective constrained control allocation problem. The key problem of direct allocation method is to determine the intersection of the desired objective vector with the convex hull of the attainable moments set(AMS). Instead of searching all the boundary of the AMS, the algorithm proposed start from a facet in the boundary of the AMS, searching the adjacent facets one by one, until the facet with which the desired objective intersected was founded. The algorithm relaxed the restriction assumed in the original method that any three columns of the controls effectiveness matrix are linearly independent, and returns optimal solutions in any cases. The high precision and the ability of real time application were validated. Simulation result shows the effectiveness of the algorithm, when applying in the flight control system of an aircraft with multiple control surfaces.
Design and determination for the front fed Cassegrain compact range
Chen Haibo, He Guoyu
2005, 31(11): 1181-1184.
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In theory, simulation and experiment, it was proved that the cross-polarization is eliminated in geometric-optics condition when the geometries ofthe front fed Cassegrain compact range satisfy the Mizugutch condition. The optimization rule on the layout and serration of the compact range was referred to, then the optimization algorithm was performed and the result was given. The front fed Cassegrain compact range (the mode K2010) was developed. The amplitude character, phase character and cross-polarization character of the quiet zone were determined in X band, Ku band and Ka band, which was compared to the calculation results with the PO(physical optics) method. The performance of K2010 was analyzed from the simulation and experimental results. Compared to other types of compact range, the front fed Cassegrain compact range provides larger quiet zone and lower polarization, which satisfies the requirement to the polarization purity in the satellite test and polarization matrix measurement.
Surface mesh generation for surface models by 2D conforming delaunay triangulation
Li Jigang, Yang Qin, Meng Xianhai, Chen Qiming
2005, 31(11): 1185-1189.
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An approach to the generation of unstructured surface meshes for surface models was presented. The only assumption is that each patch of input surface model can be treated as a single-valued function by properly specifying the projection plane. To mesh a patch of the surface model, 2D conforming Delaunay triangulation was employed on the corresponding projection plane followed by interpolating the vertices of mesh. Because of adopting cooperate-triangulation strategy, the generated surface mesh was matched at common boundary although the mesh of each patch was generated separately. Compared with advancing-front method,boundary discretization need not to be performed in advanced, the same effect was achieved when the boundary is recovered by means of boundary subdivision scheme in the conforming Delaunay triangulation procedure. By assigning element size distribution function reasonably in conforming Delaunay triangulation procedure, the generated surface mesh was a nice approximation of the underlying surface model, and self-adaptive surface mesh can be achieved. The capability of the method is demonstrated for several 3D surface models.
Object’s velocity effect on pulse to pulse frequency shifting RCS measurement
Peng Gang, Liang Yi, Wang Zhenrong
2005, 31(11): 1190-1193.
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Object's radial velocity effect on object’s radar cross section (RCS) outdoor measurement with pulse to pulse frequency shifting radar was researched. The cause of object's radial velocity make RCS measurement results inaccurate were analyzed from the aspects of object-imaging's position shifting and profile distortion. The numerical relationship between the velocity and RCS measurement error was presented using computer simulation. A method to reduce the RCS measurement error was presented base on these analysis. A method to correct the object's velocity effect was discussed bases on the architecture that the two-channels radar can measure the target on two different frequency band in the same time. The method was used to deal with the measurement data of BHEML-1 radar and the results were analyzed and compared.
Analysis of turbine flow field under low Reynolds number condition
Yang Lin, Feng Tao, Zou Zhengping, Li Wei
2005, 31(11): 1194-1197.
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The flow field in turbine was investigated using three-dimensional numerical simulation method. The flow structures in different altitude were compared and analyzed, to show the effect on flow structure and turbine performance with the decrease of Reynolds number. The results indicate that on the condition of high altitude, the Reynolds number is decreased nearly one order, and the blade loading distribution is changed, large separation is found on blade suction surface, and secondary flow and radial mixing effects enhance obviously, so that the performance is changed worse and the efficiency is dropped rapidly. These factors should be paid more attention to the aerodynamic design of turbine under low Reynolds number condition. Moreover the selection of loading distribution form is also an important factor of the design.
Multiple faults diagnosis approach for nonlinear system
Song Hua, Zhang Hongyue, Wang Xingren
2005, 31(11): 1198-1203.
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A new method for multiple faults diagnosis of nonlinear systems based on fuzzy parity equation was presented. This approach can be used to detect and identify the fault models when there are several kinds fault such as actuator fault and sensor fault simultaneously in the system. Fully decoupled parity equation for multiple faults was constructed, and fuzzy parity equation was obtained by using the T-S fuzzy model. Residual generated by the fuzzy parity equation is sensitive to one special actuator fault and all sensor faults except one special sensor, and insensitive to other actuators and the special sensor. The faults in sensors and actuators were represented as biases. The fault parameter can be identified from the information contained in the residuals. A parameter estimator based on recursive least square was designed. A simulation example on an induction motor of a railway traction system was given for illustration. Results show that the new approach can be used to detect and identify the faults of multiple sensors and multiple actuators in nonlinear systems.
Image processing algorithms for uneven heating in infrared thermographic NDT
Guo Xingwang, Shao Wei, Guo Guangping, Liu Yingtao
2005, 31(11): 1204-1207.
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In infrared thermographic non-destructive testing, to reduce the effects of non-uniform heating and increase defect contrast and inspection depths, the thermal image sequence processing algorithms were studied based on the pulsed thermography of carbon fibre reinforced plastic samples. The factors that produce uneven heating were analyzed and summarized. Three types of data processing algorithms, including deleting fitted background, polynomial fitting and integrated technique, were proposed based on the least square method. The algorithms were verified and compared by experiments and their processing effects were quantitatively evaluated by three statistical standards of image evaluation. The result shows that the deleting fitted background technique can effectively remove the bad influence of uneven heating on the defect inspection, the polynomial fitting method can decrease uneven heating effect and increase defect contrast at the same time, and the integrated approach has the advantages of the two forenamed methods and can more greatly enhance defect contrast.
Detection of SS signal cyclic spectrum based on AO technique
Wang Danzhi, Shao Dingrong, Li Shujian
2005, 31(11): 1208-1211.
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The spread spectrum (SS) signal modulated by pseudo noise code is typically cyclostationary (CS) signal. Based on the spectral correlation theory of CS signal, a cyclic spectrum detection method of SS signal using acousto-optic (AO) signal processing technique was presented. The cycle frequency and cyclic spectrum of the SS signal as well as AO CS processing model were investigated. Via AO CS time-integrated correlator, the AO correlation function (cyclic spectrum) of SS signal was detected at the cycle frequency. Compared with the conventional signal energy detection methods, the cyclic spectrum detection has better detection characteristic. For noise and interference, no matter what they are stationary or non-stationary, the cyclic spectrum detection is with the quite anti-interference capability. The simulation results show the effectiveness of the method.
First-order D-type iterative learning control for a class of nonlinear systems
Song Zhaoqing, Mao Jianqin
2005, 31(11): 1212-1216.
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The design scheme of the classical D-type iterative learning control law depends on the relative degree of the controlled systems. In order to solve this problem and the problems of the gain of relative degree, and of the higher-order differential operation, a first-order D-type iterative learning control design scheme was presented for a class of nonlinear systems with arbitrary higher relative degree based on the dummy model. The main idea of the method was constructing a dummy model with relative degree one and with gain of relative degree that can be designed arbitrary by connecting in parallel with a first-order subsystem for the nonlinear controlled systems with arbitrary higher relative degree. A first-order D-type iterative learning control law was designed based on the dummy model, so that the dummy model can track the desired trajectory perfectly,and the controlled system can track the desired trajectory within a certain error. The simulation example illustrates the feasibility and validity of the presented scheme.
Tree structured hybrid filter banks based on power complementary pairs
Liu Zhiyu, Lin Maoliu
2005, 31(11): 1217-1221.
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A near-perfect reconstruction tree-structured hybrid filter bank (HFB) was presented. The analog analysis filters to analyze input signals are not the low-pass, band-pass or high-pass filters designed by using conventional methods, but the tree-structured analog filters based on power complementary pairs,whose parameters were optimized by genetic algorithm. And the digital synthesis filters were implemented by means of the optimization method based on inverse fast Fourier transforms. 3rd-order and 5th-order analog power complementary filter pairs were designed for 4-channel tree-structure HFB. And length 63 FIR(finite impulse respouse) synthesis filters were implemented to ensure the near-perfect reconstruction. The HFB, which yields 1.06×10-7dB average deviation from 0dB distortion and -111dB average aliasing, is suitable for systems up to 15 bits resolution.
Performance loss analysis on aerospike nozzles
Ju Chunguang, Liu Yu, Han Fei
2005, 31(11): 1222-1225.
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The performance of the aerospike nozzles is influenced by many factors. To identify how much influence each factor work on the performance loss, the major factors were analyzed, including the boundary layer losses, the chemical kinetic losses, the truncated losses and the base losses, as well as the losses inherent to the design. The model of the pressure distribution on plug wall was established according to the altitude compensation capability of the plug nozzle. The results show that the truncated losses and the base losses due to the truncation of the plug are the main factors influencing the performance of the aerospike nozzle. To reduce the losses and improve the performance , the gas flow features on the spike and base should be emphatically investigated by the experiments and the numerical simulations, and these features should be taken into account in the process of the aerospike nozzle design.
Study on fast synchronization of hybrid DS/FH system
Zhang Bo, Shao Dingrong, Li Shujian
2005, 31(11): 1226-1231.
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For a hybrid DS (direct sequence) /FH (frequency hopping) spread spectrum system, a fast synchronization method was proposed. Synchronization include two processes: acquisition and tracking. In the process of acquisition, a fast frequency identification method was used to realize the hybrid DS/FH systems’ fast acquisition. In the process of tracking, based on the frequency information obtained, the receiver was waiting in a certain frequency. Through the DS signal’s acquisition tracking and demodulation processing, to get the FH synchronization information, the hybrid DS/FH system’s synchronization was completed. The mathematic model of the hybrid DS/FH system’s synchronization process was provided, the mean acquisition time expression using this method and generalized mean acquisition time formula was derived. The validity of the project was verified after simulating, in the circumstances of Gauss noise, choosing the correct threshold, result at Ec/N0= -15dB shows that the mean acquisition time is decreased almost 1/4 of the one using usual waiting method.
Parallel multi-objective genetic algorithm by adding area penalty
Li Changlong, Cheng Peng, Chen Xiaobo, Chai Xudong
2005, 31(11): 1232-1236.
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One challenge for multi-objective genetic algorithm (MOGA) is the computational cost when MOGAs were used in the multidisciplinary optimization (MDO) problems. To improve the efficiency of MOGA, a new parallel algorithm was suggested. All the individuals were distributed among processors equally, and each processor got the extremum of Pareto solutions from all processors and constructed its own penalty function. Then each processor could divide its own Pareto solutions convergence area by the penalty function. To avoid the appearance of overlapping and omitting area and reduce the convergence time, some optimization techniques were suggested. So each processor could converge to its own special Pareto solutions segment. Because the individuals computed was divided into every processor equally, in each processor the computational cost was reduced. This with the small data changed in each processor guaranteed the efficiency. Through comparing with serial MOGA (NSGA2) and the other parallel MOGA (guided domination approach), the algorithm is proved being more effective and advanced.
Set membership identification algorithm of nonlinear systems
Chai Wei, Sun Xianfang
2005, 31(11): 1237-1240.
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A new set membership identification algorithm was proposed for the robust identification problem of nonlinear dynamic systems with unknown but bounded noises. Radial basis function (RBF) networks were used to approximate unknown nonlinear dynamic systems utilizing their approximation ability according to input and output data of systems. The weights of the RBF network of the unknown nonlinear dynamic system were estimated using a linear-in-parameter set membership identification algorithm considering that the RBF network was a linear-in-parameter model and the modeling errors and system noises were bounded after the centers of the RBF network were determined. Since the result of the estimation was a set of the weights of the RBF network, it could be easily used to predict the interval of the practical system output. Simulation shows that the set membership algorithm is less affected by the distribution of the noises of the unknown nonlinear dynamic system than the least squares algorithm.
Connection-level network traffic model based on wavelet
Hong Fei
2005, 31(11): 1241-1244.
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Recent research shows network traffic exhibits drastically different statistics according to scales, including one component holding most traffic and being mostly Gaussian and the other absorbing virtually all the small scale bursts. For better understanding of this phenomenon, wavelet for multiscale analysis was introduced, a novel traffic model based on wavelet was proposed. Independent wavelet model was proved to be an ideal model for the Gaussian component, while the bursty component find a better match with the multifractal wavelet model, this novel traffic model combined the merits of independent wavelet model and multifractal wavelet model. Simulation results with the real traffic show this model is flexible and parsimonious to accommodate Gaussian as well as bursty behavior on different scales.
Ontology based resource management platform design and implementation
Zhu Lijun, Chen Qian, Liu Hui, Huang Xiaoyun
2005, 31(11): 1245-1249.
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To solve the lacking content based analysis problem on volumes of domain information resource, a domain ontology based information resource management platform trial system was designed and implemented. Costume ontology(CO) was created to represent domain concepts and the relationship between concepts. CO was used to construct the description database of managed information resource to calculate the relationship between these resource and to add value to them. CO based semantic query on the description database was implemented. The costume domain ontology modeling, ontology formal representation and storage schema were discussed. The trial system took J2EE architecture which including storage component, semantic query interface component, semantic analysis component and semantic inference component. Using resource description framework(RDF), the meaning of the managed resource was mapped to the ontology layer(CO). By semantic analysis and semantic inference, the relationship among resource could be fully used to implement the relevant information resource retrieval and semantic fusion.
Numerical simulation of infrared characteristics of liquid rocket plume
Zhang Xiaoying, Zhu Dingqiang, Xiang Hongjun, Cai Guobiao
2005, 31(11): 1250-1253.
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The infrared characteristics of liquid rocket plume, in spectrum 2~5 μm, was calculated using integral method of radiation transfer equation. The absorption of air at sea level was considered. The temperature and mole fraction of components in the cylindrical plume vary in axial and radial directions. The absorption and emission of gaseous components: H2O, CO2, CO were considered in computation. The spectral transmission of gas were calculated by the SLG model and air by LOWTRAN7.0. The spectral radiation intensity outgoing plume surface, and that after being absorbed by the air path of 0.88 km was calculated. By comparing, the results was basically accord with that in reference.
Two-segment information fusion attitude determination method for spacecraft from vector observations
Yu Yanbo, Fang Jiancheng
2005, 31(11): 1254-1258.
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The low precision characters of the integrated inertial/stellar attitude determination system consists of MEMS (micro electromechanical systems) gyros and CMOS APS star sensor. For this question, the methods of attitude determination from vector observations which suitable for this system were studied. There are several attitude determination methods suitable for the gyro/star-sensor configuration such as EKF, QUEST and optimal REQEUST. According to the different characters between the EKF and optimal REQUEST and together with the single-frame method QUEST, the quaternion was used as the attitude parameter. A two-segment attitude estimator was presented: when the estimated error of gyro drift was large, the fusion mode of EKF and QUEST was used to estimate the gyro drift as soon as possible. When the estimated error of gyro drift reduces to some low extent, the filter was switched to the fusion mode of EKF and optimal REQUEST. The results of simulation show that the two-segment estimator can estimate not only the attitude parameter but also the gyro drift. The determination accuracy of the attitude estimator can meet the attitude determination requirements of the most spacecrafts.
Design of active integrated probe-fed receiving antenna
Su Donglin, Xiao Yongxuan, Wang Guizhen
2005, 31(11): 1259-1263.
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In order to improve the gain and sensitivity of the receiving antenna system, one scheme on how to design active integrated receiving antenna was adopted in the receiving antenna and radio frequency front end system, which can bypass the traditional impedance matching network between the active circuit and the microstrip antenna. Depending on this scheme, the design of active integration between the rectangle microstrip probe-fed antenna and the front end low noise amplifier was performed. The feed of the rectangle microstrip antenna was connected with the input port of the low noise amplifier by one metal probe. When the antenna is resonant at 2.48 GHz, by selecting the proper feed position, the antenna can produce the input impendence needed by the low noise amplifier design. The active integrated probe-fed receiving antenna operates on the S band. The final measurement results show good characteristic.
Design of workflow-based integrated quality management system
Li Qing, Zhao Meng, Wen Jingqian
2005, 31(11): 1264-1268.
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To address the problem of lacking process management in a function-orientedquality management system, an integrated quality management system was designed by taking advantage of process management, control, and reconfiguration supported in the workflow technology. The principal contribution is to present a framework of workflow-based integrated quality management system, which supports process management and control for aircraft manufacturing. A three-tier system architecture based on J2EE (java 2 enterprise edition) was investigated. In particular, a workflow-enabled platform was developed by integrating a workflow middleware into the framework. The platform supports workflow modeling, execution and management, and provides necessary tools for quality management. The quality information management and process management were well combined in the system. Finally, an integration method based on XML(extensible markup language)was introduced aimed at enhancing the integration of the quality system with other management information systems. This design has been put into practice in the quality management system of a large-scale aircraft manufacture enterprise.

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