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2007 Vol. 33, No. 12

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Rotation effects on the film covering area
Yang Xiaojun, Tao Zhi, Ding Shuiting, Xu Guoqiang
2007, 33(12): 1383-1386.
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Experimental research was conducted to investigate the rotation effect on the film covering area, which is important to comprehend the mixing process of the coolant flow and the hot gas over the high pressure turbine blades. A simple flat surface with a 30° inclined film hole was positioned parallel to the hot main stream and different rotation orientations were selected to simulate the blade pressure or sides. Liquid crystal was used to supply the temperature field information over the blade surface and the average adiabatic effectiveness of the area adjacent to the film hole was selected to measure the cooling effect. Rotating speed varied in 0, 300, 500, 800 and 1000 r/min. It was found that the film trajectory could bend under the rotation condition. With the increase of the rotating speed, on the pressure side the film trajectory inclines centripetally firstly and centrifugally at last. On the suction side, the film trajectory bends centrifugally. As the momentum flux ratio kept constant, the increase of the density ratio could lead the film trajectory to incline more centripetally on the pressure side. But on the suction side, the trajectory bends more centripetally.
Parameters self-tuning fuzzy-PID combined with expert control on wind velocity control system of wind tunnels at home
Li Ke, Liu Wangkai, Wang Jun
2007, 33(12): 1387-1390.
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The structure and the characters of wind velocity control system of D-4 low velocity wind tunnel at home having been built in Beijing University of Aeronautics and Astronautics was introduced. Due to the difficulties of establishing mathematical model, the complicated nonlinear characters and the change of parameters, the wind velocity systems is not easy to control in classical PID algorithm. This problem can be solved on the basis of parameters self-tuning fuzzy-PID control algorithm combined with expert decision. The experiment proved, compared with classical PID control, the parameters self-tuning fuzzy-PID control method can decrease the overshoot, enhance the capacity of anti-dynamic disturbance, have certain robustness, resolve the contradictory between rapidity and small overshoot, and is suitable for application in low velocity wind control system.
Parametric modeling and optimization of low observability fuselage in aircraft conceptual design
Bai Zhendong, Liu Hu, Wu Zhe
2007, 33(12): 1391-1394.
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Parametric modeling method on typical sections of fuselages was studied to improve the efficiency of low observability fuselage modeling in aircraft conceptual design. Several design parameters of section curves were defined to adjust the control points of B-spline, and then typical sections of fuselage and canopy were described with single B-spline, including cutting edge, concave-convex curves, etc. Based on this method, a series of parametric templates on section curves were created. When the parameters of selected templates had been set, the practical shape of the cross section was obtained at each station, and then a low observability fuselage can be constructed rapidly. Finally, two low observability design concept models were generated to apply the proposed method, and optimized with the objective of minimal lateral radar cross section, which validated the effectiveness of fuselage optimization with parametric modeling method.
Two dimensional Voronoi grid technology applied in the DSMC method
Hou Fenglong, Cai Guobiao
2007, 33(12): 1395-1399.
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The Voronoi grid technology applied in the direct simulation Monte Carlo (DSMC) method was researched. Basing on the Dirichlet tessellation and Voronoi diagram theory, the Voronoi cells were defined by thier tessellated points and the peculiar arithmetic mapping particles to cells satisfied the statistical requirements of DSMC method. By filtering out the tessellated points too closed to the boundaries, dividing the boundaries if necessary and distinguishing the incomplete Voronoi cells defined by boundary points from the complete Voronoi cells defined by inner tessellated points, the two dimensional Voronoi grid boundary conforming problem was resolved. The Voronoi grid technology supported self-adaptive DSMC calculations. Mapping efficiency contrasts showed that efficiency of Voronoi grid was higher than triangle grid and lower than multi-level rectangular grid in the DSMC method. The validity of Voronoi grid technology in the DSMC method was confirmed by the simulation results of MEMS-based micro nozzle flow.
Burning surface calculation for grain embedded metal wires based on SolidWorks API
Xiong Wenbo, Liu Yu, Yang Jinsong
2007, 33(12): 1400-1403.
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A simpler and more accurate of propellant grain calculation which is based on SolidWorks API interface and Visual Basic has been developed for grain embedded metal wires. It can build parametrical model for grain embedded metal wires automatically and distill burning surface which occurs during burning process by SolidWorks API. As a result of the relation between burning surface and propellant thick, the interior ballistic performances can be simulated. The result shows that this calculation method is feasible and has a better precision. The calculation results are in good agreement with experiment results. It can also simulate the burning process of this type grain and be satisfied with actual engineering calculation. This software is a useful tool for difficult propellant grain calculation and propellant grain design with this type grain.
Analysis of traction trafficability of diameter-variable wheel for planetary rover
Sun Peng, Gao Feng, Li Wen, Sun Gang
2007, 33(12): 1404-1407.
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A planetary rover with diameter-variable wheels was represented which has advantages of compact structure, good climbing obstacle capability, low gravity center, and traveling stability. In consideration of lunar gravity environment and mechanical property of lunar regolith, the interaction between diameter-variable wheel and lunar regolith was analyzed by means of Bekker equation of terramechanics. The extended wheel model and sinkage were simplified, and the drawbar pull, driven torque, as well as driven efficiency of rover wheel were calculated under different slip conditions. The analytical result shows that the extended wheel reduces the bulldozing resistance, the drawbar pull and driven efficiency increase compared with that of folded wheel configuration. The range of slip for maximal driven efficiency has been obtained.
Design and performance simulation of a new type wheel with claws
Yue Ronggang, Wang Shaoping, Jiao Zongxia, Kang Rongjie
2007, 33(12): 1408-1411.
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Aiming at the disadvantages of current planetary rover wheel, a new type climbing obstacle wheel with claws was designed according to the complex planetary surface environment. Its main innovation is the claw on wheel. Mechanics analysis of the new type climbing obstacle wheel was computed, and the steady running condition was deduced. It offered designers several theory foundations. A three-dimensional planetary rover model with the new type climbing obstacle wheels was built by Pro/ENGINEER software, and kinematic and dynamic simulation of the wheel was given by ADAMS(automatic dynamic analysis of mechanical systems) software. The simulation results show that the new type wheel has strong crossing obstacle capabilities. It can scale the step whose height is 1.4 times than the wheel radius, and can adapt itself to all kinds of rough and uneven terrain environment. The new type wheel overcomes disadvantages and shortages of current rover wheels.
Calibration and compensation periodic error in quartz MEMS gyroscope drift
Zhang Haipeng, Fang Jiancheng, Sheng Wei
2007, 33(12): 1412-1416.
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It was found in experiments that the drift of quartz series MEMS(micro electromechanical system)gyroscopes had good orderliness and periodicity against other series MEMS gyroscopes, especially in short-time and high frequency sampling. In order to improve the precision of the quartz gyroscope and the performance of the system, a precise calibration method was raised by studying each period-s parameters as well as its error transfer coefficients according to error analysis theory. The experiment results not only demonstrate that the precision of the quartz MEMS gyroscopes is improved by the accurately calibrating but also testify that the obtained parameters values are applicable to compensation online in long subsequent time. It is extraordinarily necessary for the quartz series MEMS to process the precise periods calibration.
Synthesis algorithm of multifractional Brownian motion with wavelet
Wang Zhaorui, Lü Shanwei, Nakamura Taketsune
2007, 33(12): 1417-1419.
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In practice, the signals being analyzed are often very far from regular or smooth, and these irregular signals usually have many non-differentiable points, even nowhere differentiable. To describe the signal whose pointwise singularity varies along the sample path, in terms of the concept of multifractal, a new algorithm based on discrete wavelet transform for synthesis of multifractional Brownian motion was proposed. The desired local regularity of the multifractional process was obtained by controlling the weights of the wavelet expansion of the Gaussian white noise. The convergence of the synthesized process was controlled by an experimental factor. Compared with both Durbin-Levinson model and circulant matrix embedding model, this algorithm is not only time saving, but also appropriate for generating the multifractional process that is non-Gaussian and autocovariance function unknown in advance. The validity and rationality were verified by numerical experiments.
Test resource coalition formation in open flexible test system
Bian Zeqiang, Meng Xiaofeng, Chen Yue
2007, 33(12): 1420-1423.
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To solve the rapid creation of the open flexible test system (OFTS), the complicated test task was disassembled into sub-test set based on signal type at first. Consulted about the unified color and individual color of polychromatic sets theory, a best test resource coalition formation model was established. The source share among the signal type was considered in the model based on the real test system, thus the excess complex system size and the waste of the resource after the system creation could be avoided. Taking the minimum resource cost as the goal function, the coalition formation algorithm based on the ant colony optimization arithmetic was designed. The effectiveness of the model and algorithm was proved via real resource coalition formation.
Satellite selection algorithm for combined satellite receivers
Zhang Qiang, Zhang Xiaolin, Li Hongwei, Chang Xiaoming
2007, 33(12): 1424-1427.
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On the basis of the relationship between the determinant of a 5×5 matrix and five satellites- geometry dilution of precision(GDOP), a method of selecting satellites for double constellation combined receiver (e.g. GPS(global position system) and BD2(BeiDou2) combined receiver) was proposed. With this algorithm, firstly several combinations of the maximal determinant were computed, then some optimal satellites from other visible satellites for each combination were chosen according to need, lastly according to the least GDOP principle the final result was selected from previous combinations. Computer simulations indicate that compared to directly using GDOP to select satellites, more than 95% of relative ratio are lower than 5%, while computation burden reduces more than 40% with this method.
Finite field model of concatenated prime codes
Liu Qingge, Shao Dingrong, Li Shujian
2007, 33(12): 1428-1431.
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Based on the construct idea of prime codes and the transformation relation between finite ground fields and finite extension fields, the construction of concatenated prime codes was analyzed in polynomials form and the finite field model was deduced. The model indicates that concatenated prime codes are the result of a little change of finite extension field multiplication with one certain class of quadratic irreducible polynomials. This result associates the construct of concatenated prime codes to the multiplication of finite extension fields similarly to that of prime codes to the finite ground fields. Furthermore, according to the conclusion above, one rule is achieved to decide the groups- number of concatenated prime codes. These two conclusions are theoretically enlightening to extend the construct idea of prime codes to finite extension fields. And a new way is provided to construct frequency hopping sequences with longer period and more sequences based on prime codes.
Energy transmission characteristic of PLZT bimorph
Liang Lei, Wang Shaoping, Cao Feng, Deng Weiti
2007, 33(12): 1432-1435.
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The mechanism of the photostrictive effect of lanthanum-modified lead zirconate titanate (PLZT) ceramics was researched. The theoretical analysis showed that photostriction was the superposition of photovoltaic and converse piezoelectric effects. The maximal deflexion and drive force of PLZT bimorph driver under ultraviolet illumination were attained from material dynamics analysis. PLZT bimorph deflexed to the maxima under irradiation when there was no mechanical load, whereas bimorph did not do work; part of the incident energy was wasted, and the other converted into electrical and mechanical energy and stored in the bimorph driver. The magnitude of work done by bimorph driver related to mechanical load. The exporting mechanical energy reached maximum when the load was half of the maximal drive force. The research can be applied to structural design for optical driver, making the whole system get maximal energy output.
Fuzzy modeling of rate-dependent hysteresis loop in giant magnetostrictive actuator
Guo Zhenkai
2007, 33(12): 1436-1439.
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Hysteresis is a strongly nonlinear phenomenon which exists in the input and output property of a giant magnetostrictive actuator, which has influence on the precision and stability of active vibration control. So a method based on fuzzy tree model was presented to describe the hysteresis nonlinearity of giant magnetostrictive actuator. In order to obtain the data which was adapt to fuzzy tree modeling, the original one-dimension input space was first projected on a high dimension input space, then the multivalued function in one-dimension space could be converted into the single value function in the high dimension space. The proposed method has a simple architecture, which is of low computational load and is insensitive to the dimension of input-data set. The numerical simulation shows that the method is effective.
Implementation of 32k points ultra high speed FFT processor based on FPGA devices
Li Wei, Sun Jinping, Wang Jun, Li Shaohong
2007, 33(12): 1440-1443.
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An ultra high speed 32k point pipelined fast Fourier transform (FFT) processor was designed with FPGA (field programmable gate arrays) implementation. The processor can operate at 125 MHz and is able to handle a continuous input complex data stream of 1 Giga-samples per second. The FFT processor is based on MDF(multi-path delay feedback) structure which combines the features of the SDF(single-path delay feedback) and MDC(multi-path delay commutator) architectures. The memory cost of the processor was decreased compared with the MDC architectures while the speed is higher than the SDF architectures. The algorithm and design model for the processor was established and the three modules of the processor according to the design model were optimized to decrease resource cost. The design was implemented with the the Xilinx ISE development tool using VHDL and was verified with the FPGA place and router results.
Automatic geometry alignment for muti-projector image display wall
Peng Junyi, Chen Huan, Dai Shuling
2007, 33(12): 1444-1447.
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A practical and scalable alignment automation system for muti-projector display wall was constructed based on the measurement of low-performance cameras. Taking the advantage of re-alignment theory the homography matrix was refined and used to achieve seamless alignment across different areas on the projection screen. The special pattern for feature extraction and the re-alignment idea furthest decreased the effect of the cameras- performances on the alignment precision. The system can automatically align the projectors under the conditions that there are overlapped view areas between adjacent projectors and cameras can observe them. It is shown in the experiments that the re-alignment method obviously shortens the calibration period and brings us sub-pixel alignment precision. The low-performance cameras, high efficient feature extraction method and sophisticated solution for homography make the cost of expanding the system low.
Multisensor multipled hypothesis algorithm based on data compressing technic
Zhang Jingwei, Xiong Wei, He You
2007, 33(12): 1448-1451.
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In order to solve the problem of multitarget tracking in centralized multisensor situation, a new multisensor multitarget tracking algorithm was presented. At first, the algorithm permuted and combined the measurement from each sensor using the rule of generalized classical assignment algorithm. Then, all of measurements in each assignment were combined into one equivalent measurement according to their weight in the assignment. Finally, the association probability of each equivalent measurement was calculated, and then the state estimation in fusion center was obtained. Some typical simulations were used to compare the performance of the algorithm with the other centralized multisensor joint probabilistic data association (MSJPDA) method, and the results show that the performance of the algorithm here is better than that of the MSJPDA, especially under the environment of the detection probability decreasing.
Information increment and information value of demand information in supply chains
Wang Jing, Li Yuxiang, Wang Xu
2007, 33(12): 1452-1456.
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The definition and measurement of information increment and information value of demand information in supply chains were given, basing on theory of information science. It showed how a certain piece of demand information took effect in the process of making a decision on order, and how the wholesaler-s expected income varied with decision changing by establishing an order decision model. The relationship between information increment and information value was studied after analyzing information increment and information value when the actual demand was uniform distribution and normal distribution respectively. The results of equation calculation and simulation experiment prove that there is positive correlation between information increment and information value, and the information increment can influence the information user-s income. The results of the research also prove that it is very necessary to establish an effective information evaluation system for members in supply chains to increase income by improving the quality of decision information.
Digital product model support methods in aircraft collaborative development
Tao Jian, Fan Yuqing
2007, 33(12): 1457-1461.
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Effectivity and consistency of product data are the precondition of collaborative development pattern. Digital product model (DPM) acts as carrier of product data and relation information, and its effectivity will affect the purpose of collaborative development. The importance of DPM was emphasized and the definition of DPM was confirmed based collaborative development pattern. Two basic conceptions of configuration item, baseline and three new notions of applicability, availability and effectivity were proposed referring to Boeing and Airbus ideas. The review mechanism of configuration item and baseline was studied in detail. The method of ensure DPM-s effectivity was established by associating with the evolvement of baseline and DPM version in product development lifecycle under the configuration management. Finally, a case of definition model development was given to illustrate the validity of the method.
Design and simulation of highly stable and precise tracking-pointing platform
Cui Long, Huang Hai
2007, 33(12): 1462-1465.
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In order to implement high accuracy space tracking-pointing task, highly stable and precise tracking-pointing mechanism with vibration control ability was designed. The mechanism adopts 6-SPS Stewart configuration. Utilizing macro-micro actuators, high accuracy pointing movement was implemented in large workspace. Combining characteristic of actuator, the control system of this mechanism was designed. The control system has tracking-pointing, vibration suppression and vibration isolation ability. Vibration isolation uses feed forward method. Tracking-pointing and vibration suppression use PID method. Utilizing MSC.ADAMS, frequency response analyze and time domain dynamic simulation of mechanism was finished. The result shows that the mechanism has higher directional precision and better vibration control ability and could implement large scale high precision tracking-pointing function in disturbance environment.
Single-factor uncertainty analysis of project-s duration based on float
Li Xingmei, Qi Jianxun, Su Zhixiong, Wang Jing
2007, 33(12): 1466-1470.
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In order to analyze the sensitivity of variety of single activity completion time to project-s duration, by probabilistic analysis principle and approach, the probability of terminative time-s change of activity under different conditions was confirmed, and the system of decision evaluation index was designed which contains the method of confirming correlative parameters in the system on the basis of total float theorem. The sensitivity of variety of critical activity-s completion time to project-s duration was analyzed with the analysis technique of single-factor sensitivity, and how to select critical activities which are the most sensitive to total time limit from all activities considered. Finally the process was validated and illuminated by illustrating. The system is helpful to supervise and control the sensitive activity to project duration, and contribute to project scheduling and planning, which establishs theoretic foundation for analyzing multi-factor uncertainty problem of project-s duration.
Hybrid genetic algorithm for multiple process and batch scheduling in job-shop
Lin Nan, Meng Biao, Fan Yuqing
2007, 33(12): 1471-1476.
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Combined with the heuristic rule and the simulated annealing algorithm, an improved genetic algorithm GASA(genetic algorithm-simulated annealing algorithm) was put forward. This algorithm adopts the new type of POX cross operators and takes advantage of the simulated annealing algorithm which could effectively avoid the earliness problems based on the basic genetic algorithm. The availability of this algorithm was also validated through experiments. Grounded on GASA, considering the production batch, production transition time and multi-equipment process path, the problems of static and and dynamic scheduling in aeronautic workshop were researched, and then the effects brought by the different batching methods were discussed and validated as well. The algorithm now has been used in some production planning and control system in large scale enterprise.
Disclosing method for protecting sensitive certificate
Jiang Zhengtao, Huai Jinpeng, Wang Yumin
2007, 33(12): 1477-1480.
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Further investigations on the problem of disclosing sensitive attribute certificate were provided. To enhance its security assurance, cryptographic mechanisms were utilized and a certificate disclosure scheme based on which was proposed, which realized the following characteristics: At last resource demander submits part of all of her attribute certificates to the resource provider; Resource provider can receive that part of attribute certificates and he cannot get any information of the rest; Resource demander cannot get any information on which attribute certificates does the provider really get or interest; With this scheme and according to their realized agreements, they can arrange a set of different bounds for the different attribute. For any attribute, the condition that the attribute certificate can be obtained or validated only when the number of the provider participant (or limit) exceed or equal to the corresponding bound, which can protect part of right and privacy of both sides.
Semantic-based resource cooperation mechanism
Chen Jiangfeng
2007, 33(12): 1481-1485.
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In order to improve the efficiency of the resource cooperation, according to the static functional characteristics, the similarity function and function-based resource cooperation algorithm was provided; according to the runtime QoS characteristics, the runtime QoS resource cooperation algorithm was given. On the basement of above work, a resource cooperation which combines the effects of static functional resource cooperation and runtime QoS nonfunctional resource cooperation was put forward. The top-rank candidate resources which were able to satisfy the end user-s task were provided through the function-based resource cooperation, and the high quality resource could be gotten from the given top-rank candidate resources through the runtime QoS resource cooperation. The evaluation on the cooperation mechanism shows that the semantic-based service resource cooperation mechanism promotes the success rate, service quality and executes efficiency for resource cooperation.
Description language oriented to attack tree model
Tang Shujun, Li Xiaojian, Tu Shouzhong, Wei Gang
2007, 33(12): 1486-1490.
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A main problem of recent researches on network security simulation is the lack of methods to model attack and uniform description. Hence computer network attack description language(CNADL) was presented, with attack tree adopted to model attacks and describe purpose, characteristic and process of attack. Attack tree was used to model attacks and then transformed to automata model. CNADL, which was attack tree model oriented and designed in context-free grammar, described the goal, means and process of different attacks in uniform format. The interpreter translated CNADL into corresponding orders and sent them to attack drilling system. Based on GTNetS simulator, the attack drilling system tested the validity of CNADL. The experimental results show that CNADL is able to describe attack characteristics efficiently, and simulate denial of service(DoS), worm password attack and IP spoof based on GTNetS.

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