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2010 Vol. 36, No. 6

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Influence of Gurney flap on longitudinal aerodynamic characteristics of  multiple-control-surface UAV
WANG Jin-Jun, ZHANG Zi-Jun, FENG Li-Hao
2010, 36(6): 631-635.
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An experiment had been conducted to investigation the effect of different control surfaces with Gurney flaps on the aerodynamic characteristic of a multiple-control-surface tailless aircraft model. It is found that either the individual elevons and flaperons, or their combinations with Gurney flaps can increase the lift coefficient, while the drag and nose-down pitching moment coefficients are also enhanced inevitably. In contrast, when the canard wing is equipped with Gurney flaps, the lift and drag coefficients have nearly no change at the linear stage, while the nose-down pitching moment coefficients decrease significantly during the angles of attack tested. Therefore, the combinations of the canard wing and either the elevons or flaperons with Gurney flaps were further tested. The results show that such combinations can increase the lift coefficient while keep the pitching moment coefficient almost unchanged, which is benefit to improve the aerodynamic performance of aircraft.
Simulation and experiment of random errors of MEMS gyroscope
2010, 36(6): 636-639.
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The random errors of a micro electro mechanical system (MEMS) gyroscope was analyzed and modeled to improve gyroscope performance. Time series analysis was used to fit the gyroscope measurement data which had been preprocessed. State vector augmenting method was proposed to design Kalman filter. In order to verify the validity of the method, rate test and oscillating test had been done. After filtering, in the case of static and constant angular rate, the mean value and standard deviation were 55% and 12% of that before filtering respectively. However, the effect decreased when it turns to oscillating environment. Adaptive Kalman filter was adopted to solve the problem. The choosing principle of fading factor was discussed and the filtering performance of constant fading factor was compared with that of adaptive factor. The results showed that, in the case of oscillating, both of them could get a remarkable performance improvement, and the filtering performance of the adaptive fading factor is higher than that of the constant one.
Modeling and reducing of water hammer of proportional direction valve controlled ship steering system based on AMESim
Fu Yongling, Zhao Gang, Qi Xiaoye, Ji Youzhe
2010, 36(6): 640-644.
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In proportional direction valve controlled ship steering system, the proportional direction valve could generate water hammer when it changes direction. Bad affects could be lead to not only the hydraulic steering system but also the ship itself. The model of proportional direction valve controlled ship steering system was created in AMESim. The model and the water hammer simulation result were correct after compared with the test result. Then the current optimization method was used to reduce the water hammer of proportional valve, the optimization result was the parabolic curve. The simulation and the examination results show that the AMESim is fit for the water hammer modeling and simulation of the steering system. The current optimization method can reduce the water hammer significantly.
Dynamic instability of helicopter transmission rotating shafts with spline coupling
Kang Lixia, Cao Yihua
2010, 36(6): 645-649.
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To transfer torque effectively, spline coupling is widely used in rotating machinery, and it can be adopted in helicopter transmission system. Theory analysis on stability of the supercritical rotating shaft was conducted. And the corresponding experimental verification on the helicopter tail transmission shaft was developed. By installing and uninstalling O-rings on both ends of the spline, which were used to lube grease airproofing, the work state of the spline could be altered, and the conversion of the relative stability to absolute instability of helicopter tail transmission shaft could be realized. The agreement between the theoretical analysis and experimental verification indicates that the inner damping due to friction in the spline and on the supporting surface of both ends of the spline is the springhead of self-excited vibration and the stability of the supercritical shaft can be meliorated by improving the work state of spline, and they can lay the foundation of the research about the supercritical helicopter transmission shaft design.
Design and optimization on trajectory of increasing velocity along its original -velocity direction by impulse firing for ballistic missile to penetrate anti-missile system in passive ballistic curve
Zhang Bin, Ren Junxue, Wang Yibai, Liu Yu
2010, 36(6): 650-653.
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A fly dynamics model of ballistic missile to penetrate the anti-missile system in the passive ballistic curve, which was based on the increasing velocity along its original velocity direction, was established. The influences of the impulse engine work time and the impulse engine ignition time on trajectory were analyzed based on the result of trajectory simulation. With a constant total impulse, the short time-large thrust model had maximum range. When impulse engine ignited at climbing stage, the model of short time-large thrust had maximum utilization ratio of energy, while the model of long time-small thrust had maximum utilization ratio of energy at descending stage. The constraint conditions of the optimization problem of increasing velocity along its original velocity direction by impulse firing were given. The results of optimization show that the mass of impulse engine decreases 24.87%. 
Vertical flight trajectory optimization of heavy military airlift aircraft
2010, 36(6): 654-658.
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Vertical profile flight trajectory of heavy military airlift aircraft, which is often time-critical was optimized. Flight time was chosen as the cost function and divided into climb, cruise and descent parts. Flight point-mass motion equation was transferred into equivalent-energy form using energy-state method. Climb and descent segment flight trajectory optimization was carried out by applying Pontryagin's minimum principle after optimizing cruise altitude and speed. Numerical result was obtained that trajectory of such aircraft was made up of three parts:  a climb segment along a maximum feasible speed path, a maximum level speed cruise segment at lower altitude and a descent and approach segment along a maximum feasible speed path. This result will be significant for improving airlift efficiency and safety of military transport aircraft which is operated in hazardous frontline environment.
Extraction of saliency-gist features and target detection for remote sensing images
Li Zhicheng, Qin Shiyin, Itti Laurent
2010, 36(6): 659-662.
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An automatic approach to detect and classify targets in high-resolution broad-area remote sensing images is explored, which relies on detecting statistical signatures of targets, in terms of a set of  biologically-inspired lowlevel visual features. The broad-area remote sensing images were first cut into small image chips with slide window, which were analyzed in two complementary ways: attention/saliency analysis exploits local features and their interactions across space, while gist analysis focuses on global non-spatial features and their statistics. Both saliency and gist feature sets were used to classify each chip as containing target or not, through using a support vector machine. The proposed algorithm outperformed the state-of-the-art HMAX algorithm in the experiments and thus can be used to reliably and effectively detect highly variable target objects in large scale remote sensing image datasets.
On orbital maneuver window for servicing spacecraft
Cai Yuanwen, Shen Gongxun, Yu Xiaohong
2010, 36(6): 663-666.
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The development and implement of space technology made the on-orbital service be possible. On account of kinds of constraints-affection, the maneuver time and time period should be chosen carefully for the servicing spacecraft (SSC) to provide on-orbital services. The concept of maneuver window was put forward and defined, also its constraints was analyzed. The calculation of the maneuver window between circular orbits under the energy limit was discussed with emphasis. The energy-save drifting maneuver window and the time-saving quick maneuver window were studied separately according to the emergency degree of the service mission. Simulation results indicate, under the condition of limited energy and unlimited time, that the co-orbit deployment has more maneuver opportunity than the other modes, and maneuver energy is the key constraint for maneuver window.
Prediction of military UAV development cost based on partial least-square regression method
Luo Wei, Liu Lu
2010, 36(6): 667-670.
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The basic model was formulated based on the partial least-squares regression method, which has some prominent advantages in dealing with small sample and variables with multiple correlations, and the arithmetic steps of the development cost prediction of the military unmanned air vehicle were given, for there are some complex factors such as maximum take-off mass, cruise velocity,  flight altitude and so on affecting the development cost of the military unmanned air vehicle and few sample data of the military unmanned air vehicle. The data in reference [2] was tested and compared with step multivariate regression, back propagation and radial basis function neural network method. The results show that the partial leastsquares regression model is practical and efficient.
Large-stroke Hexapod platform and its vibration isolation test
Cui Long, Huang Hai
2010, 36(6): 671-675.
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In order to improve observation precision of vehicular and airborne optical equipment, large-stroke 6 degree freedom active vibration isolation platform was designed. The actuator of Hexapod platform adopted linear motor, and to use in vibration isolation mission, gapless gimbal joint was designed. The platform adopted 6-UPS Stewart configuration, had 30 kg carrying capacity, and upper mounting plate had 30 mm translational and 8 rotational movement capability. Platform control system combined proportion integral-derivative (PID) control and filtered-X adaptive inverse control method, PID controller applied  positioning control and filtered-X adaptive inverse controller applied  vibration control. 3～20 Hz sinusoidal vibration isolation experiment result shows that the Hexapod platform vibration isolation ability is higher than 90%, 5～20 Hz frequency range random vibration isolation experiment result shows that the upper plate vibration amplitude peak-peak value is reduced by 78%.
Space swept algorithm based assembly path planning method for aircraft
Qiu Xi, Wei Shengmin, Cheng Hui
2010, 36(6): 676-680.
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In order to get effective assembly path, a space swept algorithm based assembly path planning method to plan the assembly path of aircraft was presented. Firstly, by considering the rules of assembly fixtures and tools in aircraft assembly process, the whole process of assembly path planning for aircraft was formed on base of the assembly sequence. Secondly, the guide model of path planning was developed on the base of assembly sequence which was integrated with the assembly resources. Thirdly, the path obstacle space, space swept closure as well as the assembly path closure were defined, and the path was formed according to the space swept algorithm which can form a sweptvolume between the part and its kinetic orientation. Lastly, the parameters of assembly path were studied, and the assembly path was also optimized according to the threshold adjustment of interference. On base of the theoretical analysis, a case of the assembly of a fore flap was studied to prove this method can solve a practical application quit efficiently.
Eigenrotation-based rigid body tracking system with sliding mode controller
Li Tiejun, Huang Hai
2010, 36(6): 681-685.
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A sliding mode control(SMC) method was derived and applied to a rigid body attitude tracking system in the presence of dynamic uncertainties which included uncertainties and variations in its inertia parameters, uncertainties in its control actuator alignment and external disturbances. A feedback linearization was used to obtain the required angular acceleration according to eigen-rotation. The SMC algorithm was derived to make the angular acceleration of the rigid body track the required angular acceleration. Simulation results show that the proposed SMC law is globally stabilizing and insensitive to uncertainties and variations in its inertia parameters, uncertainties in its control actuator alignment and external disturbances.
Application of chebyshev spectral boundary element method to acoustic-scattering computation
Yang Mingsui, Wang Tongqing, Fan Zhenzhen
2010, 36(6): 686-689.
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On the basis of boundary element theory, combined with Chebyshev spectral element method, acoustic scattering numerical computation was studied. The second order boundary element was used in the computation of acoustic scattering field.  Chebyshev-Gauss, a spectral collocation point method, was used to realize the whole process in which spectral point were dispersed. As a result, this method overcame some shortcomings of traditional ones such as the discontinuity of normal direction and normal derivative that appeared on the nodes of surface element. With the application of a combined Helmholtz integral equation formulation (CHIEF), numerical non-uniqueness was solved and the computational accuracy and efficiency would be improved. Therefore, the new method advantage such as fast computation and high accuracy are drawn through the comparison and analysis with the traditional method.
Effect of orifices‘diameter on heat transfer and flow resistance characteristic of passage
Li Li, Xu Guoqiang, Ding Shuiting, Deng Hongwu
2010, 36(6): 690-693.
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Numerical simulation was performed to obtain heat transfer and flow resistance characteristics in a channel with zigzag divider wall. Six configurations with different diameters of the orifices were designed to predict the effect of the orifices’diameter on heat transfer of passage. The simulation results of the configurations with big-small diameter partition wall tend to agree with available experimental data. The results show that the heat transfer and the flow resistance both decrease with the diameter of the hole in the configuration with the same diameter partition wall. The heat transfer of the configuration with big-small diameter partition wall is better than that of the same diameter partition wall when the total flow area of holes is constant.
Cartesian grid technology applied in DSMC method
Hou Fenglong, Cai Guobiao
2010, 36(6): 694-699.
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The Cartesian grid technology applied in DSMC (direct simulation Monte Carlo) method was studied. A strategy of counting the boundary triangle surface elements in each Cartesian grid cell for establishing the mapping relationship from bug cells to surface elements was adopted. Further more, the bug cells were distinguished as level one bug cells and level two bug cells. In addition, a variable time step technology was used. With these skills, the Cartesian grid can match complex geometric surfaces smoothly in DSMC calculations. The self-adaptive method of this Cartesian grid was presented. A general DSMC procedure, rarefied gas dynamic tool(RGD-Tool) was developed. The classical DSMC simulations of flows passing around a sphere and an inclined baffle were carried out respectively by using RGD-Tool procedure. The results show that the discussed Cartesian grid technology work well.
Empirical research on meta-competency evaluation model based on multiple dimensions hierarchical entropy
Li Junfeng, Du Bin
2010, 36(6): 700-703.
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In order to upgrade effectiveness of human resources, reduce employing risk and evaluate individual competency, the equilibrium decision model based on multiple dimensions hierarchical risk entropy was presented for human resources evaluation of spaceflight product project. Firstly non-linear solid characters of project human resources were analyzed. Credibility and validity of these data were tested. By the way of hierarchical decomposition and dimensions propulsion, this multiple dimensions hierarchical entropy model was applied to aggregate meta-competency for evaluating human resource. There are multiple dimensions as concept skills, creativity, learn skills, reflective skills, mood skills, communication skills and problem-solving skills in the competency model. At last, one human resources empirical example was studied to demonstrate the meta-competency based on hierarchical entropy. All data of the empirical example show that this model is effective and feasibility to practical work. So this method provides one scientific evidence to upgrade the effectiveness of project human resources.
Flow superposition design method and CFD simulation for the impeller of water pump
Li Lihong, Liu Yanfang, Xu Xiangyang, Ji Fenzhu
2010, 36(6): 704-707.
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The blade of impeller, which is complicated spatial curved volume, directly influences on its hydraulic performance and running stability. Basing on the flow law of liquid, flow superposition design for the impeller of engine water pump was applied following to the flow trail. The flow of liquid in water pump was considered as the superposition of axial and radial flow at motionless and the peripheral flow at rotating, so its meridian contour and blade type could be designed with corner flow law and source-vortex flow law. According to the computational fluid dynamics (CFD)  simulation result, this method can avoid uneven pressure because of uneven spatial liquid flowing, and reduce back flow and secondary flow, accordingly reduce energy loss and increase pump efficiency.
Approach to mobile robot localization based on incremental landmark appearance learning
Wu Hua, Qin Shiyin
2010, 36(6): 708-712.
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Robot localization with omnidirectional vision becomes much difficult as the landmark appearances change dramatically in the omnidirectional image. An approach to mobile robot localization with omnidirectional vision was proposed, which used incremental landmark appearance learning to deal with changes of the landmark appearances and to provide observation information for estimating the robot pose under a particle filtering framework. Incremental probabilistic principal analysis was employed to solve the incremental landmark appearance learning problem, where the landmark appearances viewed from different angles were adopted into the learning model. The proposed method can estimate the robot pose accurately since it takes the advantages of particle filtering by means of sequential importance sampling with resampling. The experimental results demonstrate satisfactory performance with low localization error, little computation burden, efficiency, robustness to various interference in omnidirectional vision.
System maintainability allocation improved method based on the time character
Zhou Dong, Lv Chuan, Wang Meihui, Huo Lin
2010, 36(6): 713-718.
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The maintainability allocation work has unreasonable aspect in the engineering application at the present time. According to the traditional method, the allocated time can not be controlled by the design department, and it is hard to achieve the real purpose of maintainability allocation. For this question, the maintainability allocation improved method of the aviation equipment based on the time character was present. The idea is to divide into two parts for the equipment structure, one is common maintenance time, and the other is particular maintenance time. The common maintenance time is controlled by the system overall arrangement department or the higher hierarchy, and the particular time is controlled by the unit or the lower unit design. The maintainability allocation model based on the analysis of the time class to allocate the common time and the particular time severally also was presented. Finally, a case of certain kind of system on aircraft is applied, using the method base on the time character. The improved method allows the allocation time to each product unit can be truly under the control of the various design departments, and thus can really impact and guide product design, to achieve the real purpose of maintainability allocation.
Modified SAR image segmentation method based MRF with fast simulated annealing
Liu Xianghua, Zhou Yinqing, Sun Muhan
2010, 36(6): 719-722.
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Markov random field (MRF) approaches are able to implement better SAR image segmentation by combing the image intensity and structure information. However, this kind of approaches often obtains a global solution at the cost of computational burden. A fast simulated annealing method was presented by combing the prior knowledge of SAR image distribution and applied to the SAR image segmentation based MRF. In the process of segmentation based MRF, the fast method first searched the neighborhood of each pixel to find out whether there was a predominant marker. If yes, the pixel would be marked with this predominant marker in the updated segmentation field; if not, the pixel would be marked randomly as the traditional simulated annealing algorithm does. Because a prior judgment based on Gibbs distribution was introduced, the proposed method is able to obtain a global best solution very quickly. In the end, experiments were carried out on real SAR images and the results validate the feasibility and efficiency of the proposed method.
Execution engine for real-time embedded software test -design and realization
Yin Yongfeng, Liu Bin, Wang Chen
2010, 36(6): 723-727.
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In automatic real-time embedded software testing, the design and realization of test description execution system is one of the key problems. Based on object-oriented programming thought, an execution engine oriented automatic real-time embedded software test description language (RT-ESTDL) was designed and realized. The test description driven real-time embedded software testing process was studied. And then, the general design scheme of the execution was put forward. The compiling and the execution process of the engine, including the hash function and its conflict resolution and the test description execution process based on segment-based rate monotonic scheduling (SBRMS) were brought forward. The evaluation and analysis result of the efficiency indicates that the engine can meet the requirements of real-time and concurrency in real-time embedded software testing by controlling the test description scale and the concurrent execution number reasonably, and has good transportability.
Timing offset compensation algorithm for OFDM system
Sun Yuming, Zhang Yanzhong, Shao Dingrong, Li Shujian
2010, 36(6): 728-731.
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To eliminate the effect of orthogonal frequency division multiplexing (OFDM) system symbol timing offset on channel estimation, a compensation algorithm was presented. The theoretical analysis shows the phase shift is calculated as the change of statistical properties and the channel estimation error is extended when the linear interpolation is used in the channel estimation. The presented algorithm compensates the channel estimation using the characteristic of subcarrier phase shift caused by symbol timing offset. The simulation results show that, in multipath fading channel, the channel estimation mean square error of the new algorithm is 25% that of normal linear interpolation algorithm when the signal to noise ratio is 20 dB and the timing position is the middle of the cyclic prefix, so the new algorithm can shorten the meansquare error of channel estimation. The experimental results show the algorithm can improve the performance of receiver.
Routing protocol based on cross-layer design in wireless sensor networks
Wang Guangxue, Liu Kai
2010, 36(6): 732-735.
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Interference in wireless sensor networks (WSNs) not only causes packet loss and delay, but also leads to excessive energy consumption. It is necessary to mitigate interference in order to improve transmission and energy efficiencies. To achieve this objective, a novel interference-aware routing (IAR) protocol based on crosslayer design was proposed. Unlike existing contention-based routing protocol, the IAR protocol employed interference degree and energy degree to make routing decision based on an interference-aware route selection scheme. Interference degree was computed based on received request-to-send (RTS), clear-to-send (CTS) and acknowledgment (ACK) packets, and energy degree of a node was calculated based on its initial and residual energy in order to prolong network lifetime. Simulation results show that the IAR protocol achieves higher energy efficiency and better performances than both dynamic codeword routing (DCR) and ad-hoc on-demand distance vector routing (AODV) protocols in terms of throughput, packet delivery ratio and delay.
Mixed guidance method for  reentry vehicles based on  optimization
Wang Junbo, Tian Yuan, Ren Zhang
2010, 36(6): 736-740.
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The error caused by the calculating time delay of predictive guidance was analyzed for the mixed guidance based on the reference-trajectory guidance and predictive guidance for reentry vehicles. The method of error compensation was put forward. By utilizing the optimization theory, performance index function was designed and a new predictive guidance method was proposed. The reference-trajectory guidance was combined with predictive guidance which was applied in some characteristic position in the reentry process. A mixed guidance method based on the optimization for the reentry vehicles was proposed, which decreased calculating time of predictive guidance to a satisfactory level and reduced deviation and disturbance further. The simulation results indicate the strong antiinterference capacity, high guidance precision and great practical value in engineering of this method.
Denoising method to dynamic digital X-ray images and its fast implementation
Wang Gang, Yang Min
2010, 36(6): 741-744.
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For the dynamic digital X-ray imaging system, in order to solve the degradation of DR (Digital Radiography) image quality, NL-means algorithm was introduced for the DR image denoising by using the Anscombe transform. In order to solve its complex calculation and time-consuming problem, GPU (Graphic Processing Unit) was used for its high parallel computing and fast floating-point calculation abilities. During implementation, the original noisy DR image was mapped to the GPU's texture and each thread calculated one pixel. By using its multi-threads, the NL-means algorithm could be effectively accelerated in GPU. The results show that the NL-means denoising method can effectively restrain the noise of dynamic DR images, and the acceleration with GPU can speed up more than 2 orders of magnitude without the loss of resolution, which met the satisfaction of real-time denoising.
Shape optimization for contact problem based on MLPG mixed collocation method
Zhao Liang, Li Shu
2010, 36(6): 745-748.
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The theory of contact problem and meshless local Petrov-Galerkin(MLPG) mixed collocation method was introduced, the correlative formula was conducted, and the definite condition of two typical contact state was presented. The MLPG mixed collocation method was used in contact analysis through two-dimension linear basis function, cubic spline weight function and moving least square shape function. The essential boundary condition was imposed by penalty function method, the contact process of two-dimension elastic contact problem was simulated, real contact state was received by iteration, and a new stress-displacement non-linear mathematics solution model was proposed, engineering contact problem was solved and optimized with genetic algorithm, the optimization result and the change curve of objective function was presented. Numerical examples show that the proposed method is effective.
Implementation of dual CPU redundant control based on DeviceNet field bus
Wang Ding, Li Duo
2010, 36(6): 749-752.
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An implementation of dual CPU(central processing unit) redundant control based on DeviceNet field bus was introduced. Dual CPU redundant design played an important role to improve the DCS(distributed computer system) reliability. In the implementation, two CPU units and some data I/O(input/output) units were connected through a DeviceNet field bus, and DeviceNet client/server programs running in the CPU units implemented the data synchronization between the two CPU units as well as the redundant control over data I/O units. When the main CPU unit encountered some serious errors and broke down, a fake DeviceNet group 2 only client program running on the backup CPU unit helped to fast switching, and therefore the backup [JP2]CPU unit took over the control of the whole system in less than 8 milliseconds. This design was put into practice in the design for process control stations of a special DCS system and improved the system reliability.
Technology of measuring the beat-length of polarization maintain optical fiber based on Sagnac interferometer
Xu Chunjiao, Yang Yuanhong, Duan Weiqian, Yang Wei
2010, 36(6): 753-756.
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The reflectance and transmission spectrum of the hybrid Sagnac fiber optic interferometer which is consist of single mode fiber coupler and polarization maintain optical fiber were investigated and the modulation character of the spectrum was illustrated. A simple measurement method for the beat-length of polarization maintain optical fiber was proposed based on the character of the transmission spectrum. And the optimization parameter for the measurement based on the error analysis was obtained. The experimental system was set up and the experimental results agree well with the theoretical prediction. The result shows that this technique has the advantage of simple in principle and high precision, the accuracy of the beat-length measurement is better than 0.01mm.

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