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2001 Vol. 27, No. 5

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Electrochemical Investigation of Cerium Conversion Coatings Deposited on Porous Film of Anodized Aluminum
LI Guo-qiang, LI Di, GUO Bao-lan, PENG Ming-xia
2001, 27(5): 495-498.
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Cerium-rich conversion coatings was deposited on porous film of anodized aluminum by cathodic electrolysis in a solution containing 1g/L CeCl3·7H2O and 2.7g/L H2O2. Electrochemical and chemical reactions related with coating formation were studied using electrochemical methods such as cyclic voltammetry, φ-t  curve and j-t  curve tests. It was revealed that the formation of cerium conversion coatings involves a chemical dissolution process of anodized film and an electroreduction process of 4-valent-state cerium compound. Reduction of H2O2 was considered to be the major factor responsible for the occurrence of the two processes, by changing the local pH at surface of anodized film before cathodic potential reached up to hydrogen evolution potential. While the reduction of O2 was unable to trigger the occurrence of the above processes.
A Wide-Band Monopulse Antenna-Feed System
LIU Juan, Lü Shan-wei
2001, 27(5): 499-502.
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A wide-band monopulse antenna-feed system was developed by the authors. This wide-band monopulse antenna-feed system operates in S~C bands．Its key parts include the taper slot antenna, the wide band magic T and the wide band divider. By analyzing and calculating taper slot antenna and the factor of antenna arrays and studying microstrip-slotline junction and design theory of magic T, the antenna-feed system with wide-band and high gain was obtained. The validity of the design of the above antenna-feed system was verified by its agreements with experiment results.
Visualization Computing of Radar Objects in Resonance Region of RCS
JIANG Xin, YANG Zhi-ling, WANG Bao-fa
2001, 27(5): 503-506.
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With the development of visualization in scientific computing, traditional MOM for low frequency RCS has been re-evaluated. By means of advanced 3Dmodeling technology, a loop circuit method for solving the scattering field of 3Dtargets in resonance region is presented. The numerical results are in good agreement with experiment data.
Traveling Wave Computation of Low-Scattering Cabin
ZENG Zhi-yong, NING Huan-sheng, WANG Bao-fa
2001, 27(5): 507-510.
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Graphical electromagnetic computing (GRECO) is recognized as one of the most valuable methods of RCS computation in high-frequency region. For the low RCS cabin, the effect of traveling wave is remarkable and larger than that of facets and wedges in some cases. A practical example of Low-RCS target was given to prove the validity of the method by using the hybrid method of GRECO and traveling wave theory. The results were shown to have practical engineering significance.
Design and Implementation of ACARS Message Communication Server
ZHONG Qing, ZHANG Qi
2001, 27(5): 511-513.
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Client/Server model was applied to the design and implementation of ACARS message communication server. In order to improve the system performance of real-time and rapid response, a multithread technique was used. The multithread concurrent server can receive, send and distribute ACARS messages in real time. The system has already been successfully utilized in CAAC VHF data link networks center.
On the Slot Reservation Selection Algorithm aboutSelf-Organized TDMA VHF Data Link
ZHANG Jun, ZHANG Qi-shan, DENG Qiu-lin
2001, 27(5): 514-517.
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Slot reservation selection algorithm is the key to the dynamic slot reservation in Self-organized TDMA data link. The effect of the slot reservation selection algorithm on the performance of S-TDMA VHF data link was analyzed with probability analysis method, especially in the case when users' slot selection intervals overlap with each other. Computer simulations were conducted and analyzed. On the above basis, a new effective slot selection algorithm was proposed.
Relationship Between Satellite Attitude Jitter and SAR Imaging Quality
CHEN Jie, ZHOU Yin-qing, LI Chun-sheng, CHEN Yuan-zao
2001, 27(5): 518-521.
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To provide a theoretical foundation for the design and analysis of spaceborne SAR, a method quantitatively analyzing the relationship between attitude distortion and spaceborne SAR imaging quality was developed, based on a mathematical model describing satellite attitude jitter and an expression of impulse response function for attitude jitter. The validity of the theoretical results was confirmed by computer simulation.
Temperature Calibration in A Distributed Temperature Sensor System Based on Raman Back-Scattering
A Distributed, CHANG Cheng, LI Zheng
2001, 27(5): 522-524.
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Temperature calibration in a distributed optical fiber temperature sensor system based on Raman back-scattering was discussed. A very useful principle was presented on the basis of considering system stability and system temperature sensing accuracy. By measuring and studying the loss due to status and radius differences of the reference optical fiber, a solution on how to carry out calibration was also described. Experimentations indicated that not only the principle is reasonable and correct, but also it is helpful to the design of such a system.
A System on Speckle Reduction and Quality Evaluation of Spaceborne SAR Images in IDL
YAN Ying, ZHOU Yin-qing, LI Chun-sheng, CHEN Jie
2001, 27(5): 525-528.
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Speckle reduction techniques and quality evaluation for one-look spaceborne synthetic aperture radar(SAR) images were integrated into one  system in IDL language, which provides a complete computational environment for visualization and mathematical analysis of scientific data. With this system, high space resolution and high radiometric resolution spaceborne SAR images were obtained.
Analysis of Multi-Groove Circular Radiators　with Moment Method
Lü Shan-wei, GAO Wen-jun
2001, 27(5): 529-531.
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The method of moments was employed, in conjunction with the equivalent-source technique and the modal expansion theory, to analyze multi-groove and multi-mode circular radiators. No restriction was imposed on the number, width and depth of grooves, so the theoretical method and the analytical formulation are applicable to the analysis and design of wide-ranging coaxial grooved radiators. The problem of radiation from a multi-groove and multi-mode circular radiator embedded in an infinite ground plane was solved first. Then, expressions representing the elevation-plane patterns of the radiator embedded in a finite ground plane was derived using Geometrical Theory of Diffraction(GTD). The expressions for the field pattern were obtained by superposing the infinite ground plane solutions, the first-order diffracted field solutions and the axial caustic solutions in their respective regions of validity. The calculation results are in agreement with experiment measurements.
Identification of Frequency Domain Maximum Likelihood System Using Genetic Algorithm
DUAN Shi-zhong, ZHOU Yin-qing
2001, 27(5): 532-535.
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Float point genetic algorithms were used to solve the start value and convergence problems of frequency domain maximum likelihood system identification, based on errors-in-variables model. Simulations showed that it is difficult to get accurate result only using the genetic algorithm, while the traditional non-linear iterative optimization methods may lead to convergence to local minimum in some cases. By taking the advantages and overcoming the defects of the above two methods, an improved algorithm was proposed which can give the start value of delay directly and can find the global minimum precisely within a rather short time, even when cost function has a lot of local minima. In addition, the improved algorithm exhibited broader adaptability than the old ones.
On Reliability Model of SCI Interconnections in Avionics System
SCI Interconnections, ZHOU Qiang, LUO Zhi-qiang, LI Qiao
2001, 27(5): 536-539.
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The problem of reliability modeling of Scalable Coherent Interface(SCI) protocol, the candidate standard for the future avionics system, is studied. Based on basic SCI interconnection model, a task-based analysis method of system reliability is proposed. A reliability model of SCI interconnection system is developed. The reliability of butterfly interconnection in SCI avionics system is analyzed. Conclusions show that the method has a directive influence on both task division and topology selection in the phase of avionics system design.
Common Waveform Series
ZHANG Qi-shan, YAN Guang-wen, WEI Yu-chuan
2001, 27(5): 540-543.
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In addition to sine functions, sawtooth, square, triangular and trapezoidal wave all are common waveforms in electronics as well. With the help of a formula in number theory, the relations between common waveforms and sine-cosine functions are presented, and the classic Fourier series is generalized into frequency series based on common waveform, shorten as common wavefrorm series. This generalization describes the relation between signal and common waveforms and makes it possible to represent a signal as a superposition of common waveforms. It will be important in theory and techniques.
A Virtual Instrument System Based on Parameter IdentificationDeveloped to Test Permanent Magnet DC Motor
LIU Xiang-qun, WEI Zhen-zhong, ZHANG Ren, QIU Yue
2001, 27(5): 544-547.
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Parameter estimation method (based on block pulse function and least square method) applicable to virtual test system of a permanent-magnet DC motor was discussed. Electromechanical parameters of the motor was obtained through parameter estimation. Physical parameters, dynamic and static characteristics of the motor were obtained from their function relations with the electromechanical parameters. Finally, fault detection and diagnosis were conducted. It was shown that the system possesses powerful and self-contained test functions.
Optimal Control of Systems with Random Changing Structures
WU Sen-tang
2001, 27(5): 548-551.
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An approach is given to get optimal control of systems with random changing structures.Without the indicator of structures conversion, the solution is obtained to solve control problems of systems with random changing structures when system structures conversion process is difficult or unable to observe. The effectiveness of this method is proved by simulation results for an anti-interference optimal control problem of airborne obstacle avoidance system.
Decentralized Variable-Structure Control of a Class of LinearUncertain Large-Scale Systems
ZHAO Chao, SHEN Gong-zhang, WEN Chuan-yuan
2001, 27(5): 552-555.
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The paper proposes a new variable-structure control scheme for a class of linear uncertain large-scale systems with parameter perturbations, interconnections and external disturbances. The chatting and limited control problems are discussed, and proper solving methods are formulated. The proposed control algorithm is concise and easy to be realized, the closed system shows good transient properties and robustness. Simulation results show the effectiveness of the proposed method.
Application of Simulated Annealing to Global Optimization Problems with Continuous Variables
JIANG Jia-he, SONG Zi-shan, SHEN Wei-qun, QIU Li-wei
2001, 27(5): 556-559.
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Global optimization problems with continuous variables were discussed based on simulated annealing. Implementation steps were given. Practical methods of determining control parameters were introduced. According to characteristics of continuous variables, practical methods of generating new points from a current point were given. Finally, an example of computing the fundamental matrix in computer vision domain was given to demonstrate the application to continuous variables. The simulation results showed that the algorithm can efficiently solve the global optimization problems with continuous variables.
A Combined Method of High Precision Temperature Control
SONG Ming-gang, FAN Shang-chun
2001, 27(5): 560-563.
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A combined method of high precision temperature control and its application in a constant temperature trough were presented. Combining Fuzzy logic with intelligent PID control of expert type, the method fully utilizes the expert's experience of manual manipulating and quantitative operating feature of PID control. Therefore, it could meet the precision and adjusting time requirements in high precision temperature control. Moreover, a novel and simple model to modify PID parameters and a method to predict the change of temperature on-line were introduced, which are easy to implement. When used in a constant temperature trough, the control accuracy of the combined method is even smaller than 0.01℃.
Applications of Artificial Neural Network to Opto Electric Measurements
ZHANG Guang
2001, 27(5): 564-568.
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Artificial neural network technology is getting wider and wider scale application. Following a brief introduction on neural network, its recent applications to optoelectric measurements were described in detail, including online monitoring grain protein based on NIR, structured light based 3D vision inspection, X ray real time detection of welding seam defect, and precision measurements of surface roughness and sphere radius. By summarizing its advantages and limitations in these applications, suggestions and comments were given for further research efforts in this field.
Experimental Study on Film Cooling at Rotating Flat Blade Tip
WU Hong-wei, DING Shui-ting, CAO Yu-zhang, TAO Zhi
2001, 27(5): 569-572.
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The governing conservation equations were non-dimensionalized according to the theory of similarity, a series of analogous criteria were obtained to study rotating film cooling. The rotating components of film cooling were designed and set up. A series of problems, such as signal transfer between rotational and station systems without loss of accuracy, were trickled successfully. Extensive amount of experimental data were obtained to determin film cooling effectiveness and its heat transfer coefficient. The linearity of the heat transfer coefficient and dimensionless temperature ratio was driven. Experimental correlations of the film cooling effectiveness and its heat transfer coefficient at rotating flat blade tip were formulated.
Control of the Reliability of Mechanism and Relevant Breakdown Caused by the Malfunction of Coupling
SHEN Guo-shan, LIU Wen
2001, 27(5): 573-577.
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To enhance the integral machinery reliability of the mechanical system by means of minimizing mechanical movement clog and controlling correlation failure, some relevant investigations were carried out on failure mode, failure mechanism and scathe analysis. It was found that the main cause of all the mechanism troubles is the generalized deformation. This paper presents a comprehensive mode based on Gershgorin disk principium and transfiguration design. The reliability of general mechanism and relevant failure fault were well controlled by altering nonlinear coupling and fastening into linear ones, with which the generalized distortion and the morbidity of eigenmatrix can be effectively inhibited.
Failure-Rate Analysis of Repairable Systems
SUN Jin-kang, LI Zheng-neng
2001, 27(5): 578-581.
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Considering the influence of maintenance on reliability, an approach about the modeling of failure processes for repairable systems was presented, which includes the definition and formulation of failure rate. Interrelations between these rates and failure intensities, such as inherent hazard rate and failure intensity, were also discussed. To get some maintenance and repair policies of repairable systems, the formula and trend diagrams of failure rate were derived. All of these lead to an approach to the analysis of failure rate for repairable systems.
MATLAB Simulation Model of Air-to-Air Plate-Fin Heat Exchanger
SONG Jun-xiao, YUAN Xiu-gan
2001, 27(5): 582-584.
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A dynamic lumped model of air-to-air heat exchanger is established and constructed in MATLAB environment. The model can deal with dry air condition and moisture condition with the same lumped parameter method. Simulation results of some ECS indicate that the present model has great potential in the simulation research of environment control system.
Simulation of Stationary Random Process with MATLAB
PENG Jing, JIN Chang-jiang
2001, 27(5): 585-588.
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The basic definitions of stationary random process and the principles of using spectrum decomposing to simulate the stationary random process were given. The three important factors to be considered when simulating stationary random process with MATLAB including selection of signal source, simulating algorithm and corresponding parameters, and regulation caused by different definition of the power spectral density. The procedure of simulating stationary random processes with MATLAB was illustrated by two examples: air turbulence and aircraft carrier motion at sea. The tested simulation results indicate that stationary random process can be simulated very well with MATLAB.
Fuzzy Neuron and Its Computational Capability
LIANG Jiu-zhen, HE Xin-gui
2001, 27(5): 589-592.
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Based on analysis of the limitations of computational capability of a fuzzy neuron model, two improved methods on the definition of fuzzy neuron model are presented, by using non-monotonous function as restricted inspiring function and by modifying the definition domain. For the improved fuzzy neuron models, computational capability equivalence to Turing Machine is proved. The proposed models are proved to be generalizations of traditional neural networks. Finally, the characteristics of mix fuzzy neural networks are discussed.
Implementation of Dynamic ReportCreation Based on Developer/2000
LI Qing, ZOU Jie-tao, LI Zhi
2001, 27(5): 593-595.
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Output reports of database application system are usually designed in the developing process, which limits the change of use-s management requirements. This paper presents an implementation method of optional query and creating reports while the system runs based on Oracle development tool Developer/2000 and Dynamic Data Exchange techniques. Using the method, users can select the fields and records in the output report according to their own requirements. It effectly enhances system-s capability and flexibility of report generation.
On the Free Vibration of High-Speed Ball Bearing Retainer
ZHOU Yan-ze, WANG Chun-jie, LU Zhen
2001, 27(5): 596-599.
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As a basic component of mainshaft ball bearing in aero-engine, retainer vibration plays an important role in the strength and stability of the retainer and the bearing performance. With finite element method, the free vibration performance of the retainer is examined. The results show that: 1)Apart from rigid-body motion, there is no natural frequency less than 751.12 Hz for the examined retainer. 2)With the retainer vibrating like a ring as a whole, it has some local vibration modes of side and across beams. 3)The rotation of the retainer makes its natural frequency, front-and back-moving vibration frequencies unequal with each other, which makes its resonance being excited easier.
Four-Test-Winding Eddy Current Sensor for Seam Tracking and Its Application
WU Hong-jie, QI Bo-jin, WU Xin
2001, 27(5): 600-603.
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A four-test-winding eddy current sensor for seam tracking was introduced to improve the accuracy of automatic seam tracking system for sheet butt joint. Both horizontal and vertical deviation information can be gained from testing the eddy current induced by the excitation winding. In addition to advantages such as non-touch with work pieces, high sensitivity and rapid response , the sensor is also suitable for non-magnetic material. An automatic seam tracking system based on the eddy current sensor has been developed. The principle ,processing circuit and experiment results of the system were presented in detail.
Analysis of Kinematics of Three-Branch Space Robot
REN Jing-yi, SUN Han-xu
2001, 27(5): 604-607.
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The kinematics of a three-branch space robot mechanism was analyzed by presenting its model and discussing its three working modes. The space robot is a kind of serial-parallel mechanism when it is working in carrying and cooperating modes. Since six out of its twelve joints are independent in this case, it is difficult to analyze and control this robot. By using influence coefficient method, the motion constraint equations of the mechanism were derived. The mapping of input and output was established. The inverse kinematics about velocity and acceleration were also solved.
Application of Micro Input-Output Theory to Enterprises' Logistics System
ZHENG Yun, WEI Fa, JIANG Xing
2001, 27(5): 608-610.
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Based on the structure and the character of enterprises' logistics system, application of dynamic and stochastic production function which describes the input-output relation of an enterprise to logistics scheduling was discussed. The type, quantity, time and space of a flow of produce nodes can be expressed by the dynamic and stochastics production function. By introducing periodic production capacity into the model, the dynamic and stochastic model was improved. The results indicated that better logistics schedule can be obtained with the improved dynamic and stochastics production function.
Experiment Data Acquisition System of Low Power Arcjet Thruster
TANG Hai-bin, JI Luo-shuan, LIU Yu, DAI Wu-ye
2001, 27(5): 615-618.
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With an introduction to the experimental setting and the data acquisition system of low power Arcjet thruster, measuring principles of engine operating thrust, current and voltage were highlighted, together with descriptions about measuring methods of parameters, hardware configuration, and performance of data acquisition system, as wellas rules and methods of software development. Typical experimental results were given to reflect the experiment process exactly.

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