Advanced Search

2005 Vol. 31, No. 06

  Previous Issue | Next Issue 
Display Method:
TSK-DRFNN and its constrained optimization algorithm
Xu Chunmei, Er Lianjie, Hu Hongjie
2005, 31(06): 595-598.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1441
Abstract:
A novel DFNN(dynamic fuzzy neural networks )based on TSK(Takagi-Sugeno-Kang) fuzzy model was presented to the nonlinear dynamic system. The DFNN was constitutive of static networks and dynamic networks. The static networks realized premise and defuzification part. The recurrent dynamic networks realized by FIR filter was used for realizing consequence part. Beside this a new algorithm, constrained optimization method-FUNCOM(fuzzy neural constrained optimization method)was suggested for reducing the convergence time of networks parameter. The network training task was formulated as a constrained optimization problem. The proposed dynamic model equipped with the learning algorithm was applied in a nonlinear dynamic system. Comparisons with other FNN(fuzzy neural network) and DFNN (dynamic fuzzy neural network)were given and discussed, indicating the effectiveness of the DRFNN(dynamic recurrent fuzzy neural network) and the algorithm.
Study of flow control over different noses with single hole microblowing
Sun Shuyuan, Deng Xueying, Zhan Huiling
2005, 31(06): 599-603.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 788
Abstract:
The SHM(single hole microblowing) as a new perturbation active control technique has been applied to the slender body with different model noses at zero sideslip and high angle of attack. The analyzed and contrasted results of the distribution of the surface pressure distributions and the sectional side forces with the former results of the slender body in the same flow conditions show that the SHM’s control effect to the slender body is due to that the two asymmetric vortices over the slender body model are sensitive to the nose perturbations. The analyses indicate that the SHM’s control ability has strong adaptability to various slender body at high angles of attack, and its control ability is determined by the original state of the flowfield around the slender body.
Neural　network　gain scheduling　design for large envelope curve flight control law
Zhang Ping, Yang Xinying, Chen Zongji
2005, 31(06): 604-608.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1081
Abstract:
A 3-layer BP(back propagation) network is developed for the gain scheduling flight control law in a large flight envelope curve for a flight by wire flight control system. It can replace the traditional gain scheduling according to the altitude, Mach number or dynamical pressure which is only one-parameter adjusting and then difficult to find the adjust rule and so the stability in hole flight envelope curve, specially for those flight conditions between the designed points, can’t be guaranteed. The design procedure included choosing a BP network with middle layer of 6 points only and its parameter train. The outputs are the designed optimal robust 8 feedback gains. This network realized double parameters (altitude and Mach) gain adjusting. The illustration shows the neural network can give the same control parameters at the designed flight conditions and then the response can be the same good as before. It gets a good control effect at other un-designed flight conditions, also for the system with about 50% dynamical modeling error. It gives more finely carve up result of the control parameters between all flight conditions and shows a strong extrapolate ability.
Software imitation for unmanned aerial vehicle landing scenes
Yang Peng, Wang Rui, Zhou Fuqiang, Zhang Guangjun
2005, 31(06): 609-613.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 928
Abstract:
To offer a cost-effective solution to the research of vision-guide algorithm for UAV(unmanned aerial vehicle) with vertical takeoff and landing capability, the imaging principle and imitation technology of UAV landing scenes based on the theory of machine vision was employed. The pinhole camera model including lens distortion parameters was established. Moreover, a method of adjacent region search was introduced to decrease the singularities in the imitation images caused by the lens distortion. To get more veracious imitation of landing scenes, some main interferential factors of the unmanned vehicle landing, such as the blurring induced by the light amplitude non-uniformity, image motion, as well as the noise from electronic and photometric source, were also considered. The software for real time generation of scene images was developed by C+ +　and windows operating system. The results of simulation including images and data are presented at the end.
Study on measurement of relative motion of satellite formation flight
Li Chenguang, Han Chao
2005, 31(06): 614-617.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 879
Abstract:
In satellite formation flight, the measurement and determination of independent relative orbit is one of the most important techniques of formation flight. The traditional techniques of using star sensor, radar and GPS(global positioning system) signal to determine relative orbit are considered. Relative orbit determination which is based on pseudo satellite technique is considered. Pseudo satellite technique means that carrier generators and receivers are assembled onboard, and are used to measure the distance between satellites. In these projects, differential carrier-phase GPS sensors are used, and nonlinear equations are solved by optimization methods. These methods of measurement adapt different situation. On the base of measurement results from previous three projects, using the concept of relative orbit elements, precision of orbit determination is improved by Kalman filter. Emulation calculations indicate that the request of keeping formation can be satisfied, and a part of results is presented.
Multiple object anti-collision RFID technology with dynamic slot allocation
Wu Jing, Xiong Zhang, Wang Ye
2005, 31(06): 618-622.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 847
Abstract:
To identify multiple objects simultaneously assuming that the number of labels is not known in advance, multiple objects anti-collision RFID(radio frequency identification) technology and its application system model were presented. The collision solution in ISO/IEC15693 standard was improved, with the self-match mode in address access policy and the dynamic slot allocation. These were used to solve collision problem and approach the expected target during identifying process. A method was discussed to determine and optimize the system parameters. Based on the model and the cycle of anti-collision identification, a system was developed and applied in a project of smart management system in library. The results of experiment indicate that the identification performance is more effectively and accurately. This technology can satisfy more requirements and its application range is still extended.
Novel closed loop system and output signal processing of digital Coriolis mass flowmeter
Zheng Dezhi, Fan Shangchun, Xing Weiwei
2005, 31(06): 623-626.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1116
Abstract:
In the processing of designing Coriolis mass flow measurement system, the novel digital method for processing the signals and calculating the results was introduced. The high performance parallel analog to digital converter (A/D) was utilized to sample the whole signals of the sensor. The sample data were deeply analyzed and processed by the high performance floating point DSP (digital signal processor). The classical signal processing method was used to filter the sample data and calculate the phase difference of the two signals, and that the mass flow and density of the liquid were calculated. The system was controlled and the output results were displayed and transferred by the single chip processor and the FPGA (field programmable gate array). Furthermore, the novel digital closed loop was brought forward in the closed loop resonant circuit, the digital circuits and digital signal processing methods were used to realize the traditional AGC (auto gain control) in the closed loop circuit. The experimental results show that the offset and the precision of the system are improved.
Research on synchronistic multi-ignitions of hydrogen-oxygen resonance ignitor
Yu Nanjia, Zhang Guozhou, Song Yana, Cheng Shengqing
2005, 31(06): 627-631.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 256
Abstract:
New hydrogen-oxygen resonance igniter is designed to use in synchronistic multi-ignition for aerospike nozzle engine. Ignition start time, delay time, repetition of multi-ignition and lifetime of igniter are tested. It can be found from performance tests that the new hydrogen-oxygen resonance igniter with quick starting, short time delay for ignition, good repetition and long life time. Two igniters are used in every synchronistic ignition tests. The pipeline’s influence to synchronization is analyzed. Two ways are put forward for shorten the time difference of synchronistic. It can be concluded from total 5 times synchronistic ignition tests that the new hydrogen-oxygen resonance igniter can satisfy the requirements of synchronistic multi-ignition for aerospike nozzle engine and other liquid propellant rocket engines which need synchronistic multi-ignition.
Numerical dispersion analysis for 3 -D ADI-FDTD method using higher-order spatial difference
Zhang Yan, Lü Shanwei
2005, 31(06): 632-636.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 194
Abstract:
Attention was focused on the numerical dispersion property of 3-D ADI-FDTD (alternating-direction implicit finite-difference time-domain) method using the higher-order spatial difference. First, the iterative formulas of the numerical dispersion relation for the higher-order spatial difference were derived. And secondly, the numerical dispersion values were computed and compared for the second-order, fourth-order, sixth-order and tenth-order spatial difference along the maximum phase-velocity direction and the minimum phase-velocity direction, respectively. And consequently the numerical dispersion was investigated as a function of higher-order spatial difference. Finally it is found that the fourth-order spatial difference is better than others for the uniform cell case.
Computation of fuel regression rate in classical hybrid rocket motors
Tian Hui, Cai Guobiao, Wang Huiyu, Zhang Zhenpeng
2005, 31(06): 637-641.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 166
Abstract:
The combustion characteristic in classical hybrid rocket motors has been studied. The heat transfer process in the gas and the solid fuel has been considered. Coupling computation is presented by the regression rate equations based on the heat transfer theory and the Arrhenius law. The regression rate at various oxidizer mass flow rates, axis distances, ambient operating temperatures and times is obtained. Fuel regression rate mainly infects with oxidizer mass flow rate and axial distance. Regression rate increases as oxidizer mass flow rate increases and decreases as axial distance increases. The temperature sensitivity of solid fuel in a hybrid rocket motor is low and we need not assign a weight margin for variations in ambient operating temperatures. Adiabatic combustion temperature at various oxidizer mass flow rates and grain length is obtained by thermodynamic calculation and has a maximum as oxidizer mass flow rate increases. The results are in agreement with the some references and useful for further study.
Approach of calendar life extension for aircraft structures
Liu Wenting, Wang Zhongbo
2005, 31(06): 642-646.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 172
Abstract:
To extend service life of existing aircrafts approaching the end of their original life at the expiration of calendar life while fatigue life is far from running out due to low operation, a calendar life extension approach was proposed based on evaluating technique for life system of aircraft structures under corrosive condition. Methods of identifying candidates for life extension were discussed. Accumulated damage caused by fatigue and corrosion was analyzed to separate the candidates into different classes. On the basis of fatigue life evaluated in general environment (at room temperature and in laboratory air) and expected calendar repair intervals, the remaining fatigue life that considering the effects of corrosion and continued service years were calculated from loading and repair histories using fatigue life evaluation approach in corrosive environment, from which service life was reliably extended for typical operation. Life extension results along with repair schemes for a wing of a fighter shows effectiveness of the approach.
Some influencing factors of rotor vibratory loads prediction under high speed state
Wang Bo, Li Shu, Hu Jizhong
2005, 31(06): 647-651.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 277
Abstract:
Based on the rotor airflow environment and blades movement, which would be produced when the helicopter flighted forward with high speed. It was analyzed the influence on the hub vibratory loads prediction by unsteady aerodynamics model, dynamic stall model, induced-flow distribution, elasticity deformation of blade, synthesization of hub loads and the method of numerical calculation. The hub load model includes the Leishman-Beddoes unsteady dynamic stall model, dynamic inflow theory and coupled blade movement between flap and torsion. The state-space method was used to solve the equation, which was fit for computer calculation. A calculation program was built up. Comparing calculational results of several models, it is revealed that various analysis models have great influence on hub vibratory loads prediction precision, and that aerofoil stall and induced velocity distribution are primary influencing factors. It is appropriate that more advanced induced inflow model and unsteady aerodynamics are introduced in hub vibratory loads prediction.
Study on comprehensive evaluation of cockpit ergonomics and its application
Li Yinxia, Yang Feng, Wang Lijing, Yuan Xiugan
2005, 31(06): 652-656.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 241
Abstract:
Comprehensive evaluation of cockpit ergonomics plays key role in the new-type cockpit development. At previous period, during the development of aircraft cockpits, some judge standards were proposed in order to ensure design quality without allowing for ergonomics evaluation. There are not any appropriate and operational evaluation index and method to direct the cockpit ergonomics evaluation. This leaded to several problems conflicting with ergonomics in the cockpits design. In terms of these problems, a novel integrated approach was proposed. It is characterized with soliciting, synthesizing experts judgment, taking into account the fuzzy of ergonomics evaluation. Therefore this approach can be made the comprehensive evaluation of cockpit ergonomics more objectively and scientifically. This provided a theoretical basis and a practical method in order to compare different design schemes. Utilizing the method, the geometry ergonomics of an aircraft cockpit was evaluated roundly, and the results have the approval of aviation engineering experts.
Research on intelligent simulation modeling library of three-axis virtual flight motion simulator
Liu Zhenghua, Er Lianjie, Chen Jingquan, Wu Yunjie
2005, 31(06): 657-661.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 354
Abstract:
To solve intelligent and rapid design problem of model library of three-axis flight motion simulator, an advanced approach of intelligent simulation model library of virtual flight motion simulator was proposed, based on intelligent parametric design, genetic algorithm, virtual reality and Pro/Toolkit interface tools. Genetic algorithm was used to optimize model parameters on the basis of a common product model library, which was generated by secondary development approach of Pro/Toolkit and parametric design; still more, an open software platform was designed and implemented to model assembling and real-time simulation during a virtual developing environment. The simulating results indicate the above method could be used to design and optimize the model's parameters quickly and effectively at engineering analyses. Having added intelligent methods and a common interface that can compensate for the shortages of types and capacities of table’s model library, the limit to the above intelligent model library is released and this method's application range is extended.
Novel batched patch caching algorithm for streaming media
Qin Shaohua, Li Zimu, Cai Qingsong, Hu Jianping
2005, 31(06): 662-667.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 352
Abstract:
In distributed streaming media delivery system, an important topic is how to reduce the consumption of backbone network bandwidth. By deploying the proxy at the edge of network, it made response to a group of local clients’ request and forwarded the multimedia data streamed out of the server. An efficient algorithm called batched patch pre-caching (BPP) was proposed, which tightly combined the server scheduling with proxy caching strategies. In terms of the distribution of clients’ request arrival at current time, the proxy allocated the corresponding buffer units in advance and cached data in segments from the ongoing multicast stream started at server. These cached data could be shared by subsequent requests till they were evicted from the proxy. The results of theoretical analysis and experimental simulation show that this algorithm can significantly reduce the bandwidth consumption on backbone link, and has very good adaptability for the variation of request arrival rate.
Integrated power and attitude control system based on VSCMGs for agile small satellite
Tang Liang, Xu Shijie
2005, 31(06): 668-672.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 252
Abstract:
The multi-projects attitude maneuver problem for ASSAT(agile small satellite) with VSCMGs(variable speed control moment gyros) as actuator was investigated. Under some limits, such as, the saturation of actuators, the requirement of attitude maneuver, the measurement and tracking ability of sensors, a nonlinearly integrating power and attitude controller was designed. The quaternion drift resulting from frequent maneuver was tuned. A VSCMGs steering law was provided. According to the singularity indicator of configuration, the steering tasks including singularity avoidance and wheel speed equalization were assigned soundly. Two corresponding methods were designed. The law was switched form one method to another if the indicator reached the defined condition. A numerical example for the IPACS(integrated power and attitude control system) with VSCMGs of pyramid configuration was given. The simulating results show that the ASSAT is able to satisfy simultaneously the requirements of the rapid speed attitude maneuver and stability, as well as the energy control and wheel speed equalization.
Analysis of observability and the degree of observability in autonomous celestial navigation
Ning Xiaolin, Fang Jiancheng
2005, 31(06): 673-677.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 330
Abstract:
The type of celestial measurement used in the autonomous celestial navigation system is one of the most important factors, which effect the precision of position determination greatly. There are two main celestial measurements. One is the angle between the lines of sight to a star and earth core. The other is the star elevation angle which is the angle between the lines of sight to a star and the edge of earth disk. These two common celestial measurements and their measurement equations were presented. The performance of the system using different kind of celestial measurement was analyzed based on the observability and the degree of observability of the celestial navigation system. The condition number of the observability matrix is adopted as a scalar measure of degree of observability. The effectiveness and the validation of this analysis method were confirmed by the results of computer simulation.
Modulus prediction of a polymer matrix composite reinforced with fly-ash hollow microspheres
Cao Feilong, Li Huanxi, Shen Zhigang
2005, 31(06): 678-681.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 233
Abstract:
Based on a self-consistent three-phase model and Mori-Tanaka theory, general expressions are deduced to calculate the effective volume modulus and the effective shear modulus of a composite containing several sorts of hollow microspherical reinforcements. Then, the effective modulus of a polymer matrix composite reinforced with fly-ash hollow microspheres is predicted, as a function of the volume fraction, the average size and the inner pressure of the microspheres. The calculated results agree with experimental measurements satisfactorily, suggesting that the modulus of the composite is determined mainly by the volume fraction and the average size of the microspheres, while the effect of their inner pressure is negligible.
Detection of underground cracks and thin weak layers using blasting vibration
Long Liping, Wu Yanfeng, Ding Hua, Fei Binjun
2005, 31(06): 682-685.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 257
Abstract:
By using the assertion that the propagated wave signal mainly comes from the natural vibration of geophysical structure after blasting, a new technique is proposed for detecting underground large scale cracks and thin weak layers. This technique indicates that the local stiffness decreases, owing to the exist of the cracks or thin weak layers in the medium, which directly effects the vibration velocity and frequency of the medium. The character of cracks or thin weak layers can be detected by the signals (including the vibration velocity and frequency) received on the ground if placing the source of blasting vibration near cracks or thin weak layers. The calculations were performed by a recently developed SPH(smoothed particle hydrodynamics) method and shown the contrast of the blasting vibration signals between the situation when cracks were horizontal and inclined. The results drawn a conclusion and showed the possibility of this method.
Analysis of the effects of microwave leakages on the accuracy of optically pumped cesium frequency standards
Pan Shunkang, Feng Keming, Wang Wei
2005, 31(06): 686-689.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 226
Abstract:
One of the major factors which effect the accuracy of optically pumped cesium frequency standards is caused by microwave leakages. Fourier transform is the major method to analyze the frequency offsets of small optically pumped cesium frequency standards, which is limited to analyze the case of atomic velocity being in narrow distribution. Formula of the frequency shift as a function of microwave leakages are derived by analysis and calculation. The results of calculation and analysis indicate that the magnitude of frequency offset caused by leaking microwave fields is in dependence on the length of the free field region,microwave power and the phase,amplitude and the position of the leaking microwave fields. The derived results are consistent with the conclusion which was educed by using the method of Fourier transform. However, the method is not limited by the velocity distribution of atom.
Numerical simulation on lateral jet interaction in supersonic flows
Wen Jie, Zhao Guilin, Hu Liang, Peng Hui
2005, 31(06): 690-695.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 254
Abstract:
It was validated that Fluent can be used in numerical simulation on lateral jet interaction by comparing with the experimental results. Using Fluent, the lateral jet characteristics at different jet pressures and different angles of attack in supersonic flows is numerically investigated. The results indicate that in supersonic flows, with increasing of jet pressures, the high pressure region before lateral jet enlarged, and the wraparound effect strengthened. In the cases of angles of attack, comparing to windward side jet, the high pressure region before the leeward side jet enlarged, the jet wraparound effect in the region of leeward side moved forward, and the control of leeward side jet was more effective. The affected regions of wraparound effect is confined in regions from 0° to 90° on missile surface.
Study of transistor steady-state operation life test by method of controllable junction temperature
Li Jihong, Jia Ying, Kang Rui, Zhang Dejun
2005, 31(06): 696-699.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 335
Abstract:
Analyzing the various problems of current steady-state operation life test standard, it is pointed out that, not measuring and controlling, transistor junction temperature in current transistor steady-state operation life test can lead to fatal inaccuracy of the test results. To increase the accuracy of the test method, a steady-state operation life test method with additional measuring and strictly controlling transistor junction temperature, in the highest temperature range, is given. Bipolar transistors of the type of 3DD820 and 3DD15D (with F2 metal-pack) are taken as an example in the study to verify the method of controllable junction temperature. Analyzing result of simulated experiment data shows that the test method can increase availably the accuracy of the transistor steady-state operation life test method.
QoS management model based on policy for grid application service
Yuan Man, Hu Jianping, He Rui, Ma Jian
2005, 31(06): 700-704.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 394
Abstract:
A quality of service(QoS) management model for grid is proposed by R.Al-Ali, the issues for grid QoS are divided into QoS of application layer, QoS of grid middleware and QoS of network layer. Research focus on expression for application layer service level agreement(SLA) by extending WSDL and optimization issues etc.. The research is a little for regarding application quality of service and network layer service of quality as whole. Therefor, a kind of QoS management model for grid based on policy is proposed. The motive is to shield differences for mapping application services’ QoS into transport services’ QoS from all kinds of QoS mechanism model employed by all organizations or different QoS level employed by application services for grid. When organization employs differentiated services(DiffServ), the QoS management model for grid is simulated, primarily. The simulated results show this QoS policy management model for grid can be integrated into OGSA to implement QoS management for grid application service.

Copyright © Journal of Beijing University of Aeronautics and Astronautics

Address: Editorial Department of Journal of Beijing University of Aeronautics and Astronautics, 37 Xueyuan Road, Haidian District, Beijing Post Code: 100191 Email: jbuaa@buaa.edu.cn

Supported by: Beijing Renhe Information Technology Co., Ltd.