Advanced Search

2007 Vol. 33, No. 05

  Previous Issue | Next Issue 
Display Method:
Improvement of dual-Euler method for full scale Eulerian angles solution of aircraft
Li Yuejun, Yan Chao
2007, 33(05): 505-508.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 3492
Abstract:
To overcome the shortcoming of the original dual-Euler method, i.e., it presumes that the range of pitching angle was limited to and it can-t be used for continuous solution of super-maneuvering flight when the pitching angle was beyond this limited range, improvement was made to solve Eulerian angles for full scale continuously by introducing a discriminant function that can obtain the only one corresponding solution for both positive Eulerian system and negative Eulerian system. To validate the new method, a simple model of super-maneuvering was numerically simulated with the improved Dual-Euler method, and R-K algorithm with variant time steps was used for time integration. Results showed that the numerical solution was in perferct agreement with the theoretical solution.
Fast alignment model and method for inertial navigation system
Wang Xinlong, Ma Shan
2007, 33(05): 509-513.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1041
Abstract:
A fast alignment and calibration method of inertial navigation system (INS) were approached from a control theory point of view. Using the Lyapunov transformation was proposed for transforming the conventional strapdown inertial navigation system(SlNS)error model. And the equivalence of SINS and gimbaled inertial navigation system (GINS) error model was discussed. Using a semblable transformation which based on physical insight and the so-called pseudostates vector instead of the true states were proposed. Consequently, the observable error states are uncorrelated with the unobservable ones, and the best observable sub-space of INS was found. Based on the simplified model, the fast estimation methods for the azimuth error and calibrating the drift of gyroscopes were creatively proposed. It reveals that the azimuth error and the drift of gyroscopes can be entirely estimated from the estimation of leveling error rate, and without using gyro output signals.
Fatigue life evaluation and test verification for civil aircraft structure under corrosive environment
Yang Hongyuan, Liu Wenting
2007, 33(05): 514-517.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1084
Abstract:
Rationality of the fatigue life evaluated method for civil aircraft structures under corrosive environment was validated by test for the chordwise joint parts of wings which were typical fatigue critical parts of civil aircraft structures. And the fatigue life of this part under corrosion was evaluated. The pre-corrosion curve was obtained by pre-corrosion and followed fatigue test in common environment on simulated specimens of this critical part. The corrosion-fatigue influence factor was obtained by corrosion-fatigue test on the same specimens. Pre-corrosion and corrosion-fatigue alternation tests were carried out on large-scale simulated specimens. And the synthetical correction factor of corrosion under typical using condition was obtained. The correction factor of the alternative test was also obtained by evaluated method. The comparison between the two results shows that the evaluated method is rational and validity. And the fatigue life evaluated result of the chordwise joint parts of wings under corrosion was given.
Design of damping-ring for vibration control in labyrinth air seals
Zeng Liang, Li Lin
2007, 33(05): 518-522.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 975
Abstract:
The design and application of severed damping-ring to rotor/stator components are effective in protecting labyrinth air seals and the cylindrical walls of annular chambers against flexural vibration and fatigue failures excited by various disturbing forces. The dynamic analysis of contact system was complex due to its non-linear and chaotic behavior in the process. The theory for vibration control in labyrinth air seals was built up by elastic mechanics and contact mechanics. The dynamic response of labyrinth air seals with different damping-ring and contact pressure was analyzed by dynamic compliance method. The simulation results confirmed the validity of the proposed model and method and showed that the damping-ring could reduce the amplitude of the labyrinth air seals notably. There were the best parameters of damping-ring, which lead to the best effect of vibration control. The vibration control of damping-ring was different to different modal shape of labyrinth air seals.
Carbon dioxide accumulation of space station crew quarters
Fu Shiming, Xu Xiaoping, Li Jindong, Pan Zengfu
2007, 33(05): 523-526.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1762
Abstract:
In order to analyze the accumulation process of CO2 expired by crew in pressure cabin without proper ventilation and to evaluate the possible medical hazards, a computational fluid dynamics (CFD)model of crew staying in a given space station quarter was built to simulate the unsteady process of respiration. The concentration of CO2 in exhaled air and the pulmonary ventilation varied with the concentration of CO2 in the inhaled air based on physiological experiments. The results for partial pressure of CO2 at typical locations and different intervals were presented based on simulation. Finally, a maximum allowable time that crew can stay in quarters without ventilation, some placement principles of CO2 monitors and some precautions ensured crew-s life safety in similar conditions were proposed.
Optimal actuator placements for shape control of adaptive piezoelectric truss
Xian Kuicheng, Huang Hai
2007, 33(05): 527-530.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 845
Abstract:
With piezoelectric actuators as control elements, the basic equations of shape control for adaptive truss was formulated. A mathematical model of optimal actuator placements was presented, in which the actuator locations and the control voltages were taken as design variables, and the weighted presentation of the shape precision, control energy and number of actuators was taken as the objective function. This model subjected to the strength of the structure, the limit of nodal displacement and the maximum control voltage of actuators. Because the actuators and the ordinary bars have different element stiffness, every reasonable allocation of actuators could result in the change of whole stiffness matrix. If genetic algorithm was directly applied, an extremely large number of structural analysis would be needed. In order to decrease the number of structural analysis, a new method was proposed, in which the multi-point approximation, genetic algorithm and quadratic programming were combined. The results of examples show that the proposed method has high efficiency.
Mechanical properties of 2A12 Al alloy at transient heating
Wu Dafang, Song Hao, Gao Zhentong, Yan Zhenqian
2007, 33(05): 531-534.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1375
Abstract:
Testing and determining the pivotal parameters such as ultimate strength and thermal stress at the complicated condition of transients heating is very important to the reliability estimate, life prediction of aerospace materials and security design of the high-speed flight vehicle. Because there are no ultimate strength and other important token parameters at high temperature transients heating environment in the intensity design handbook yet, the high temperature ultimate strength and other mechanical properties of 2A12 Al alloy under different transient heating temperature and load environments was obtained by using experimental simulation system of the transients aerodynamic heating for high-speed flight vehicle. Reliable basis was provided for studying the loading capacity and weight lightened of aerospace materials and structure at transient heating environment.
System model simulation and control method used in environmental simulation chambers
Li Ke, Pang Liping, Liu Wangkai, Wang Jun
2007, 33(05): 535-538.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 996
Abstract:
According to the dynamic state characters of the environmental simulation chamber, a lumped parameter model of temperature and a mathematical model of control system is established to accurately control the temperature of the environmental chamber to measure up to GJB, raise temperature rate and promote control precision. An expert control method is introduced into the design of the temperature control system which is simulated on the platform of MATLAB. By contrast the simulated result with the experimental data, the validation of the lumped parameter model has been proved and the expert control method has been showed with the advantage of no-overshoot, fast response, high precision and great efficiency. The presented methods for the simulation and the control system provide great references to the research on the control laws of other similar problem and show great significance to the relative research field.
Fuzzy variable structure control for lunar gravity-turn landing
Zhu Jianfeng, Xu Shijie
2007, 33(05): 539-543.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 989
Abstract:
Based on fuzzy variable structure control, a new guidance law of gravity-turn landing has been developed for the terminal descent phase of lunar soft landing. The sub-optimal sliding surface and fuzzy controller were designed to drive sliding variable converging to zero that would make a soft landing on the lunar surface safely. The bias of the descent engine-s thrust,the estimation of the lander-s initial mass and the lunar gravitational acceleration,the disturbances of initial conditions,the measurement error of sensors and attitude tracking error were considered. The Monte Carlo simulation has demonstrated that the guidance law is robust to all bias and disturbances. Therefore, the guidance law designed is feasible. It requires only slant range and slant range rate, and it is easy to implement in lunar soft landing mission.
Relative attitude estimation and control schemes for the final approach phase of spacecraft rendezvous
Zhu Renzhang, Lin Yan
2007, 33(05): 544-548.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1066
Abstract:
Motion equations of relative attitude between the target and chase spacecraft were elaborated for the final approach phase of spacecraft rendezvous and docking. Two algorithms of extended Kalman filtering based on vision observations were used to estimate relative attitude, one is through attitude estimation of the target, and the other is directly using motion equations of relative attitude. And two control schemes were presented to execute the relative attitude control. One of them is the phase plane control method by using constant control moment and optimal damping, in which the attitude control system can be simplified into three independent two-order systems to obtain the switching function, and the other is based on the quaternion feedback control, using eigenaxis rotation and linear two-order system to design feedback gain coefficients. The phase plane control method is relatively simple but needs more consumption than the quaternion feedback control.
Affects of temperature and error compensation for fiber optic gyro
Wang Hai
2007, 33(05): 549-551.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1135
Abstract:
The thermal characteristic of fiber optic gyro(FOG) is one of difficult questions, it is a efficient method to improve the thermal characteristic of FOG by modeling. The characteristic of thermal affect induced nonreciprocity of optic loop was introduced , and it is one of the main reasons that affect the steability of Bias and scale factor of FOG. The thermal affect produced by the inner instruments of FOG is the main reason of warm-up time. And the warm-up time can be shortened by modeling and compensating. The influence of surrounding temperature for FOG is random. The error can be modeled and compensated by temperature model. The error model of temperature drift and scale factor of FOG is settled. The raw data of FOG is compensated with the model and the validity of the model is tested.
Unscented quaternion particle filter application in micro-satellite estimating attitude
Wang Chen, Fang Jiancheng
2007, 33(05): 552-556.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1164
Abstract:
To solve the problem of low precision characters and non-Gaussian distribution noise of the micro-satellite attitude determination system, UPF(Unscented particle filter) was proposed. Based on the different characters between the UKF(Unscented Kalman filter) and PF(particle filter), UPF uses the UKF to generate sophisticated proposal distributions. UPF can not only avoid the limitation of the EKF(extended Kalman filter) and the UKF which only apply to Gaussian distributions but also avoid the limitation of the standard PF which can not include the new measurements. The MEMS(micro electronic mechanical system) gyros and CMOS APS(complementary metal oxide semiconductor active pixel sensors) star sensor were applied as attitude sensors, the method of attitude determination used the error quaternion as the attitude parameter, presented a UPF attitude estimator. The attitude determination filter was constructed and the stochastic noise was adopted from the MEMS gyro. Then the UPF characters were analyzed. The simulation results showed that the suggested method can improve the system performance. The determination accuracy was higher than the UKF while the number of the particle was lesser than standard PF.
Fast stereo edge-matching algorithm based on corner-guidance
Li Haichao, Zhang Guangjun
2007, 33(05): 557-560.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1933
Abstract:
A new fast and robust edge-matching algorithm guided by matched corners was presented. In the whole matching process, the corner constraint and the edge constraint were proposed to guarantee the matching speed. First, the matched corners were used to guide the edge matching. How to use the previous matched corners to guide the edge matching was shown. Furthermore, region-growing idea was introduced to get matched edges quickly. Second, the edge constraint was proposed to limit the search area in several pixels, then epipolar constraint was used to achieved matched points, if necessary the cross correlation was also utilized. Numerous experimental results with various images clearly demonstrate that the benefit of integrating matched corners into the edge matching procedures is obvious, and with the two new constraints this method seriously improves the speed and the correct matching ratio is higher than 97%.
One-dimension angle-oriented projection template matching
Yin Runmin, Li Bohu, Fan Shuping
2007, 33(05): 561-564.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1281
Abstract:
Refer to two key stages in template matching between two overlapping images: template selection and iterative matching, an one-dimension angle-oriented projection template matching method was proposed. The matching process firstly evolved a template selection discipline based on gray level difference segmentation to reduce the sensibility to image noise and illumination changes. After the segmentation, a well post intensity projection into angle-oriented array by linear interpolation was used to accelerate matching process and to maximum the employment of edge information. The method at last implemented an angle-oriented reformed AD(absolute differences) matching principle both to reduce miss-matches conduced by viewpoint rotation and to obtain rotation between reference and target other than correspondences coordinates. With aid of analysis of matching process respect to different cases under consideration of speed and precision, experimental results proved that the proposed approach works well over most overlapping images and is fast enough for real time applications.
Improved security enhancement for a dynamic ID-based remote user authentication scheme
Duan Xiaoyi, Zhang Qishan, Liu Jianwei
2007, 33(05): 565-567.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 867
Abstract:
Smart cards are secure, compact and intelligent data carriers, which can offers strong authentication and guaranteed non- repudiation. With the traditional authentication solution, the static password is rarely altered and maintained in the verifier table on the server. This is bringing forth the important attacks of replay attacks, guessing attacks, modication attacks, and stolen-verier attacks. However, the dynamic ID-based authentication solution can solve the problem. I-En Liao et al proposed a dynamic ID-based user authentication scheme using smart cards. The scheme has a lot of advantages, such as avoiding a variety of attacks, mutual authentication and no verifier table, but it can′t resist to stolen attack. A improved scheme was presented to remedy their weaknesses. Compare with Liao-Lee-Hwang′s scheme, the improved scheme not only avoid stolen attacks but also reduce the computational costs.
Relationship between PCB material and power/ground impedance
Su Donglin, Wang Xiaoxiao
2007, 33(05): 568-571.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 2605
Abstract:
To mitigate PCB(printed circuit board) power/ground impedance, which is a great negative influential factor to signal and power integrity of high-speed multilayer PCB , the relation functions among PCB power/ground resonant impedance,resonant frequency, resonant quality factor and the electromagnetic parameters of power/ground planes structure were deducted based on cavity resonant model. According to the deductions above, two main ways to reduce PCB power/ground resonant impedance from the aspect of selecting conductive and insulating materials whose electromagnetic parameters are more helpful to reduce power/ground impedance were developed. These two ways include using conductive material with high permeability and low conductivity and adopting insulating material with high permittivity and loss tangent. The latter full-wave simulation results prove the effectiveness these two ways.
New optimal control allocation method for flight control system
Yang Lingyu, Gao Jinyuan, Shen Gongzhang
2007, 33(05): 572-576.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1155
Abstract:
Control allocation method was investigated with the background of aircraft with multiple control effectors. A new optimal control allocation method, bases sequence control allocation, was put forward. The optimal objectives were divided into control objective and mission objective, and the control objective should be fulfilled firstly. The actuators were recombined, and the efficiency vectors of the actuators were treated as the bases of multidimensional space. All of the bases were sequenced according to the control object and the mission objective. Then the optimization of redundancy system was transformed to a sequencing problem. Comparison with other allocation method and control system simulation results show the bases sequence method can achieve the objective accurately and optimally, and can be computed in real-time. The response of the control system is rapid and accurate, and shows good decouple performance among axes.
Enhancement of a timestamp-based password authentication scheme
Qi Wenhua, Zhang Qishan, Liu Jianwei
2007, 33(05): 577-579.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 704
Abstract:
Yang and Shieh have proposed a timestamp-based password authentication scheme using smart card. The weakness of Yang and Shieh-s scheme is submitting password in plaintext and not authenticating key information center(KIC)by user. The new scheme improved the process of registration, login, authentication and update password. The user submitted the password-s hash value instead of the password-s plaintext, and shared the secret information with the KIC. Submitting the password-s hash value is the same as password in authentication, and avoiding the password-s exposure. With the secret information, the user can authenticate the KIC. The new scheme can overcome all of the above vulnerabilities, can resist the forged login attack and never revel the privacy of user even if the server is attacked.
Phase estimation of sinusoid signal based on DFT and error analysis
Li Chunyu, Zhang Xiaolin, Zhang Zhan, Chang Jiang
2007, 33(05): 580-584.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1722
Abstract:
A fast and accurate estimation technique of initial phase of single-tone signal based on the phase of discrete Fourier transforms (DFT) spectrum was proposed. The initial phase is obtained by removing the frequency item in the multinomial using the DFT coefficient which is from two discrete sinusoid signal sequences of different length. The root mean square error (RMSE) formula of initial phase estimation under Gaussian white noise was derived that presents the relationship among RMSE, fast Fourier transforms (FFT) length and signal noise ratio (SNR). The parameters in the formula were studied and optimized to minimize the RMSE. The process of which is to solve the integer programming problem with the objective function that RMSE is minimal. Through Monte Carlo simulation, the performance of the improved technique was compared with other typical algorithms and Cramer-Rao lower bound (CRLB), the RMSE formula is found to be effective.
Workflow-based project management system for complex software prototyping
Liu Li, Mao Fei
2007, 33(05): 585-589.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1628
Abstract:
Modeling and simulation for a complex software prototyping system were computer supported cooperative work process. To effectively manage its business process and data and thus improve the efficiency of the whole system-s work, a workflow-based project management system was proposed. It was comprised by system management, project management, workflow management, document management, message management and information management. The hierarchical and modularized architecture and the components of this system were illuminated. Particularly, the workflow architecture, workflow modeling and running were thoroughly explained. The elements of the model and modeling mechanism included multi-instantiation, dynamic creating and revising of the workflow. Finally, the application of the project management to a virtual prototyping system for a weapon developing platform was introduced.
Algorithm of weighted association rules mining with multiple minimum supports
Zou Likun, Zhang Qishan
2007, 33(05): 590-593.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 999
Abstract:
A new model of weighted association rule was presented in order to solve the problem that data item have not the same importance in datasets. Based on this model, a new algorithm of mining weighted association rules with multiple minimum supports was proposed. The algorithm allows the user to specify varied minimum supports and items weights to reflect the importance and frequency of each data item in datasets .The algorithm aims to deal with problem that items have different importance and varied frequency in transaction database and find more interesting rules which involve both frequent and rare items. The correlative properties of model and algorithm were given and the theories were proved. Finally, the algorithm was tested on the experimental data. Experiment results show that the new algorithm is effective for large databases.
Application of pre-interpolation S-shape acceleration/deceleration in CNC look-ahead nterpolation algorithm
Cao Yunan, Wang Tianmiao, Chen Youdong, Wei Hongxing
2007, 33(05): 594-599.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 2114
Abstract:
Aiming at improving the interpolation efficiency without lowering the path accuracy, the velocity look-ahead control in CNC(computerized numerical control) was introduced. Firstly, the interpolation geometry elements linking vector angle model, which was separated into line-connect condition and circle-connect condition, was proposed. The CNC velocity look-ahead control algorithm was presented. This novel algorithm can find the approximate optimal velocity adaptatively based on the maximum number of look-ahead segments and the geometric properties of the interpolation path, then the high connected velocities between segments can be achieved. Because introducing the acceleration attenuation in acceleration zone and deceleration zone, the S-shape acc/dec(acceleration/deceleration) can improve the flexibility of interpolation. By combining the advantages of the look-ahead control algorithm and the S-shape acc/dec in high velocity condition, a novel S-shape acc/dec CNC look-ahead interpolation algorithm was introduced and realized. This algorithm feasibility has already been proved in real CNC system.
FEM design of cruciform biaxial tensile specimen based on limit stress analysis
Han Fei, Wan Min, Wu Xiangdong, Wang Haibo
2007, 33(05): 600-604.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1284
Abstract:
The cruciform biaxial tensile test is an effective and practical method to realize the process of complex strain paths for the investigation of subsequent yield behavior and forming limit of sheet metal, and the key questions should be solved including the large deformation, homogeneousness of stress distribution and the method to measure the stress in the center region. Using cruciform specimen with thinning center region, the necking even fracture was realized. Three types of cruciform specimen with different geometrical shape of thinning center region were presented, and the homogeneous distribution of stress, the appearance of largest deformation and the avoidence of stress concentration in the center region were analysed. A mathematical method was discussed to calculate the stress in the center region. The result shows that the cruciform specimen with square thinning center region is the superior device for the investigation of forming limit stress diagram(FLSD) to obtain the more homogeneous stress distribution in the center region, to realize the large deformation and the fracture appears in the center region more easily, and to control the stress concentration preferably.
Primary calculation of electronically controlled hydraulic power steering
Gao Feng, Liu Yahui, Ji Xuewu, Guo Xiaolin
2007, 33(05): 605-607.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1251
Abstract:
Electronically controlled hydraulic power steering (ECHPS) improves driver-s ‘road feel’ because it has alterable assistance character. Steering gear model and bypass ECHPS model were built based on the hydraulic principle of the control valve and ECHPS. A simple formula suited the two models was used to analyze the assistance character of steering gear and ECHPS. The bypass ECHPS parameters- affections were analyzed by changing basic gap- width or slot-s radius of the control valve, or torsion bar-s stiffness of steering gear or both of basic gap- width and slot-s radius. The electromagnetic valve- affection was also analyzed by changing the orifice-s figure of the spool. The results show that the assistance character of the bypass ECHPS is determined mostly by the control valve of the steering gear, it has relations with the electromagnetic valve else.
Plasma spraying of the nano-structured TiO2 coatings and its photocatalytic properties
Yu Qinghe, Zhou Chungen
2007, 33(05): 608-612.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1058
Abstract:
The starting nano-TiO2 feedstock was agglomerated by spray-drying process. Nano-TiO2 coatings on transparent glasses were prepared by plasma spraying. The coating proceeded heat treatment at 300℃,400℃ and 500℃ respectively. The phase structure and the morphology of the TiO2 coatings were characterized by X-ray diffraction(XRD), scanning electron microscope(SEM) and transmission electron microscope(TEM). The porosity of the TiO2 coatings was tested by mercury porosimetry method. The result shows that the content of anatase TiO2 in the sprayed coatings is approximate to 30%~50%, and its grain size is about 10~30nm.The porosity of the TiO2 coatings is less than 6%,but has a great influence to the photocatalytic properties. After heat treatment at 300℃,400℃ and 500℃, the coating becomes denser and has a lower porosity, which leads to a decrease in photocatalytic properties. Sprayed nano-TiO2 coating obtained without heat treatment at the spraying current of 400A has the best photocatalytic property.
Concept design integrated system and constellation architecture exploration
Guo Aibin, Mi Jie, Dong Xiaoqin, Deng Jiati
2007, 33(05): 613-617.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 873
Abstract:
The method of rapid architecture selection and concept design was further discussed. The elementary models of satellite constellation′s architecture selection and concept design combined with concept design process were introduced. Risk and uncertainty analysis were integrated into the models. The integrated system of satellite constellation concept design was realized by using system design optimization framework(SDOF). The design process of the integrated system was given. The satellite constellation architecture selection and concept design proceeded with the interactive, evolving and collaborative fashion. The concept design optimization could be executed automatically, and the operation of design task unit could be monitored and controlled. After the completion of satellite concept design optimization, the design report′s context and style could be tailored by the costumers. The example for the satellite constellation for observing the earth was presented and its optimal result was achieved by using the multi-island genetic algorithm. The result demonstrates the usefulness and validity of the system.
Motion tracking and recognition of human hand in master-slave manipulation for dexterous hands
Li Jiting, Ren Dawei, Zhang Yuru
2007, 33(05): 618-621.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1022
Abstract:
Acquiring the motion information of human hands is a very important research problem in the master-slave grasping system for dexterous hands. Used to be the human-computer interface for the master-slave manipulation system for dexterous hands, a binocular stereo computer vision system was investigated to track and recognize the dynamic moving fingertips of human hands. A corresponding identifying algorithm and the experimental system were proposed. Experiment results show that the longest time is 0.4ms to simultaneously recognize the four targets in two images of left and right ones, and the recognition rate reaches 100 percent when the human hand moves in usually used speed, which illustrate that the presented method meets both the real-time and accurate requirements.
CBR methodology application in fault diagnosis of aircraft
Li Qing, Shi Yaqin, Zhou Yang
2007, 33(05): 622-626.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1414
Abstract:
CBR(case-based reasoning) is a problem solving technique of using previous experience and cases to find a solution to new problems, which is suitable for those areas of experience-rich. CBR methodology was applied to the fault diagnosis and maintenance decision support of aircraft due to the abundant repair experience accumulated in after-service of aircraft. According to the requirement of aircraft maintenance, the research into the method of aircraft fault diagnosis using CBR was conducted and key techniques, including the case base development, case representation, case retrieval, adaptation and retain, were investigated. The case representation was discussed in detail, and a case retrieval model of combining the character field match with the KNN(K-nearest neighbor) method was established and applied. A framework of aircraft fault diagnosis system was proposed. The prototype system was developed and an application example was given.
Product development two-factor risk model and simulation based on DSM
Zhang Hanpeng, Qiu Wanhua
2007, 33(05): 627-630.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 909
Abstract:
To solve the risk measurement of product development with iterations, a modeling method to evaluate the risk of schedule and cost in product development was constructed, and a simulation algorithm was given to analysis the risk of product development process. The model was constructed by two stages, rework probability matrix and rework impact matrix were firstly established based on design structure matrix(DSM), which described the relationships between schedule, cost and iteration. The evaluation model was then set up according to schedule and cost uncertainty, iteration uncertainty and the structure matrix. At the same time, the idea to decrease schedule and cost risk of product development was introduced through reducing iterations. Finally, a case was presented to illustrate the model, which indicated the model can measure product development-s schedule and cost risk, and also decrease schedule and cost risk by adopting product development sequence optimization based on DSM. This is useful to measure and control product development risk.

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.