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2012 Vol. 38, No. 12

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Fault diagnosis of direct-driven electromechanical actuator based on ensemble empirical mode decomposition
Liu Jun, Wang Zhanlin, Fu Yongling, Guo Yanqing
2012, 38(12): 1567-1571.
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Based on the ensemble empirical mode decomposition(EEMD), an fault diagnosis method was proposed to diagnose complex faults of the direct-driven dual-redundancy electromechanical actuator (DDDR-EMA). By adding different finite amplitude Gaussian white noises to the signal, EEMD keep the signal continuous in different time span. EEMD well solved the problem of mode mixing involved in the empirical mode decomposition, as well as kept adaptation. The vibration signal from the fault diagnosis experiment of air-borne DDDR-EMA was decomposed by EEMD, a group of the intrinsic mode functions were obtained, and several methods were used to extract fault features from different signal frequency bands. The experimental result verified that EEMD can improve the analysis precision of fault signal, and can diagnose complex faults of airborne DDDR-EMA more accurately comparing with EMD.
Ignition and flame holding ability of plasma torch igniter in a supersonic flow
Wei Baoxi, Ou Dong, Yan Minglei, Xu Xu
2012, 38(12): 1572-1576.
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In order to study the application of plasma torch igniter in the scramjet engine, a numerical and experimental study was conducted in a Mach 2 supersonic flow with the ethylene and hydrogen. A detailed analysis of ignition and flame holding characteristics was done at the fuel equivalence ratio from 0.1 to 0.55, and the total temperature between 1 500 K and 1 950 K. The results show that the plasma torch has a positive effect on the ignition process, but the promotion on combustion efficiency is unapparent. An 8 step 9 species and a 3 step 6 species reaction model were used to simulate the ethylene supersonic combustion. The numerical results of 8 step reaction model agrees well with the experimental results.
Dependability oriented avionics embedded software development framework
Niu Wensheng, Li Yahui, Wu Ji
2012, 38(12): 1577-1581.
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A systematic methodology was provided to facilitate the development of dependable embedded avionics software. The dependability primarily denotes to reliability, security and real-time. The dependability attribute model was defined to derive the key aspects to be specified in the stages of analysis and design. A V-model extended process model was proposed to support the co-modeling of system and software. At last, the dependability oriented development methodology was proposed. It consists of model-based requirement analysis, component-based design and system configuration and integration. During the design of the development framework, the characteristics were considered that software tasks embedded in a common integrated platform have to use the resources in a competitive and sharing way due to the limitation of resources. The effects of these characteristics on the reliability, security and real-time are also included in the design.
Fast autonomous guidance algorithm for spacecraft far range rendezvous phasing
Zhao Shuge, Chen Tong, Xu Shijie
2012, 38(12): 1582-1586.
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A fast autonomous guidance algorithm was designed based on classical orbital elements for spacecraft far range rendezvous phasing in near-circular orbit. For arbitrary initial argument of latitude difference,the phasing maneuver was divided into three stages—the initial orbit, the phasing orbit and the adjusting orbit according to the relationship of argument of latitude difference and semi-major axis difference. Coplanar orbital correction and phase maneuvering were done in the initial orbit. In the phasing orbit, the argument of latitude difference was adjusted naturally because of the semi-major axis difference, and then the orbit maneuver from the phasing orbit to the adjusting orbit was implemented. In the adjusting orbit, the apogee altitude and the apogee altitude of chase spacecraft are adjusted to the same as those of target spacecraft at first. Furthermore, a coplanar orbital correction was done again to eliminate the cross-track difference. All orbital maneuvers were given as guidance impulses and implemented in the orbital special points. Precise orbital simulation results show that the fast autonomous guidance algorithm for far range phasing maneuvers is feasible.
Routing algorithm of AFDX network based on trajectory approach
Liu Cheng, Li Hang, He Feng, Lu Guangshan
2012, 38(12): 1587-1590,1595.
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Static routing algorithm of virtual link (VL) is a key technique in avionics full duplex switched Ethernet (AFDX). A VLs’ static routing algorithm based on the trajectory approach was proposed for the real time demand of VLs. This algorithm gets each VL’s delay limit ratio first, and then configures VLs in accordance with the size of VLs’ delay limit ratio (from large to small) with the help of the corollary from the trajectory approach. This algorithm was compared to the minimum hops algorithm and the load balance algorithm in a typical configuration of AFDX. The result of the simulation shows that the minimum hops algorithm uses the least network resource, the load balance algorithm make the network flow balanced, but only this algorithm makes all the VLs’ maximum delay up to their limit.
Numerical simulation based on CE/SE method for airfoil flow with shock wave
Cui Shuxin, Gao Lin, Gao Ge
2012, 38(12): 1591-1595.
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A new numerical scheme was developed to avoid using double spatial grids to capture shock wave through the original space-time conservation element and solution element (CE/SE) method on the 2-D structured quadrilateral meshes. The design of the new scheme was based on the redefinition of conservation element and solution element as well as one of solution points involving both cell centers and vertices. Numerical simulations for flows around airfoils involving shock wave were implemented using the new scheme in combination with Courant number insensitive scheme(CNIS) and local time-stepping method. The results computed from the modified scheme, comparing with that achieved by the original CE/SE method and an advisory group for aerospace research and development(AGARD) report, show a better resolution of the shock wave and that there is no obvious numerical oscillatory before and after the shock wave. The new scheme provides a more accurate and stable means for computing shock waves in flows over airfoils.
Multi-target data association algorithm based on tracking-differentiator
Li Yong, Huo Wei
2012, 38(12): 1596-1600.
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From the fact that position and velocity of a moving object can not vary discontinuously, a data association algorithm based on tracking-differentiator was presented for multi-target tracking in unknown clutters. The tracking-differentiator was applied to obtain positions and velocities corresponding to the measured data in target gates and multi-target data association in unknown clutter environment was realized by comparing these positions and velocities with target position and velocity at the previous moment. Since the algorithm utilizes measured data directly and does not depend on the prior statistics knowledge about target movements, sensor noise and clutter properties, it has good capability of data association in the environment with lower dense clutter and known number of targets. The algorithm possesses low computing burden and simple structure, and separates with target state filtering algorithms completely, which facilities modular design, combination with other filtering algorithms and implementation in practical engineering. Simulation results illustrate the effectiveness of the proposed algorithm.
Safe trajectory optimization with control failure effects estimation
Li Yinan, Yang Lingyu, Shen Gongzhang
2012, 38(12): 1601-1605.
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Control surface failures will change the aerodynamics of the aircraft and reduce its maneuverability as well as controllability. The traditional path planning methods based on the normal point-mass model have difficulty in generating an optimal and safe trajectory. To characterize the impaired motions accurately, the sideslip angle and the side force caused by failures were introduced into the simplified point-mass model, and post-failure aerodynamics were estimated. To address the problem of declined controllability and maneuverability, the change rates of the control variables were appended to the modified model and penalized in the cost function. Finally, gauss pseudospectral method was applied to optimize the safe trajectory. Numerical results considering aileron and rudder failures showed that equations of motion and the constraints of both states and controls were satisfied while safe and smooth trajectories were achieved.
Type synthesis for sensing mechanism of superconductor gravity gradient based on constraint pattern
Jia Ming, Yang Gongliu
2012, 38(12): 1606-1610.
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Based on constraint pattern, the type synthesis for sensing mechanism of superconductor gravity gradient was produced. The independent sensing mechanism of inline or cross component of gravity gradient was analyzed, and the freedoms of motion and constraint pattern of mechanism were deduced. The simultaneous sensing mechanism of two components was presented for the measurement application. The constraint type was determined by the freedoms of motion and constraint pattern and equivalent to flexible cylinder joint, which could be built by flexible elements according to parallel mechanism form. By means of modal emulation, it can be concluded that rigid rod with flexible spherical hinge on two ends of rod is applicable for the sensing mechanism of two components. The stiffness emulation results indicate that the stiffness of design motion is small, the stiffness of parasitic motion is large, and coupling of motions is little. It is proved that the simultaneous sensing mechanism of two components is appropriate for the measurement system of superconductor gravity gradient.
Novel decoupling-compensating control based on incremental model for bank-to-turn missiles
Zeng Xianfa, Wang Xiaohu, Zhang Jing
2012, 38(12): 1611-1615.
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The characteristic and existed problems of traditional dynamic inversion control for bank-to-turn (BTT) missiles were analyzed in detail. A novel decoupling-compensating control approach was proposed for BTT missiles. In this approach, an incremental BTT model which demonstrated the transition from current dynamics to desired dynamics was established. And by doing so, the portion of model which was difficult to observe or with large uncertainties was eliminated. Then based on the incremental model and dynamic inversion, the incremental decoupling-tracking control law was designed which relied less on model than the traditional dynamic inversion. To further improve the control law’s adaptability to disturbances, a simple disturbance estimation and compensation strategy was proposed. Finally, simulation results validate the effectiveness of this approach.
Optimization design about the rigid spline of the discrete teeth harmonic drives
Wang Su, Bai Xin, Chen Shixian
2012, 38(12): 1616-1618,1624.
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The transmission performance was analyzed , based on the device structure and transmission principle of the discrete teeth harmonic drive. The optimization design model for the rigid spline was established based on the relationship between the character of rigid spline and the transmission performance. And that the pressure angle of rigid spline tooth profile minimum as the optimization design goal was confirmed to improve the transmission efficiency; the optimizing design variables were confirmed according to the tooth profile curve equation of the rigid spline to achieve the parameters of the rigid spline optimized, and the constraint conditions were confirmed on the basis of the transmission properties to ensure normal transmission. The example shows the method above can effectively reduce the pressure angle of rigid spline tooth profile, which improves the transmission property.
Main circuit topology and working status of inverter in on-site induction brazing of tubes
Zhang Wei, Miao Zhifei, Qi Bojin
2012, 38(12): 1619-1624.
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Considering the characteristic of on-site induction brazing of tubes, the voltage source series resonant circuit was adopted as main circuit topology of inverter in the square wave power. The impedance of series resonant circuit and the working status of inverter main circuit were discussed. Based on the above, the best working status of inverter was proposed. A new frequency tracking scheme, which combines the proportion integration(PI) control method with the IC SG2525A, was proposed to adjust inverter operating frequency to keep the induction heating circuit working in quasi-resonance state. This technology not only ensures the inverter safe and reliable work, but also enhances the induction brazing power source heating efficiency and power factor.
Performance analysis and comparison of flexure bearings with different profile lines
Chen Xi, Yuan Zhongyu, Qi Yingxia
2012, 38(12): 1625-1628.
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It is crucial to analyze the performances of flexure bearings which would influence the overall reliability of cryocoolers. The performance parameters of flexure bearings include the stress distribution, axial stiffness, and dynamic radial stiffness and so on. The Fermat flexure bearing was designed, which was analyzed and compared with the other two kinds of flexure bearings in the above aspects by finite element method (FEM) and experimental study. The three flexure bearings were fabricated, and the axial stiffness and dynamic radial stiffness were tested individually. The testing results agree well with the finite element analysis (FEA) results. They indicate that the Fermat flexure bearing owns the highest stiffness ratio. The radial stiffness of the Oxford flexure bearing is minimum. The maximum stress value of the Fermat flexure is highest among the three flexures, but which falls well below the material fatigue limit stress. Hence, the Fermat flexure bearing is superior to other two kinds of flexure bearings.
Fatigue crack monitoring of metallic structure based on eddy current array sensor
Ding Hua, He Yuting, Jiao Shengbo, Du Jinqiang
2012, 38(12): 1629-1633.
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To monitor the fatigue crack of aircraft metallic structure in real-time, a scheme for fatigue crack monitoring of aircraft metallic structure based on flexible planar eddy current array sensor is put forward. The characteristics of sensor were analyzed via semi-analytic model, and feasibility of scheme was verified through monitoring experiment based on constructed fatigue crack monitoring system. The result of semi-analytic model shows that the curves of phase difference and amplitude ratio between sensing channel and driving channel varying by lift-off and the conductivity of material under test have singularity and the amplitude ratio changes greatly. The result of fatigue crack monitoring experiment of 2A12-T4 aluminum alloy under constant load indicates that the first channel of sensor is capable of monitoring on accumulated damage and the other three channels are capable of quantitative monitoring on fatigue crack, with monitoring precision of 1mm. The proposed flexible planar eddy current array sensor achieves the whole lift cycle monitoring of specimen from accumulated damage to fatigue crack propagation.
Heat transfer in rotating trailing edge channels
Zhao Bin, Deng Hongwu, Qiu Lu, Ding Shuiting
2012, 38(12): 1634-1638.
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The heat transfer characteristics of static and rotating turbine blade trailing edge channels with staggered-ribs and pin-fins was experimentally. The model was a wedge shaped channel. Ribs were staggered on trailing and leading walls (p/e=7), pins of two different sizes were placed in the pin-fin region. Reynolds number ranged from 6 100 to 33 000, while the Rotation number was up to 0.6 in the experiments. The results indicates that the difference of heat transfer decreases along the radial direction. Heat transfer in rotating condition increases on the trailing side, while on the leading side it decreases overall. Heat transfer near the blade tip increases on both trailing and leading walls. The scale of transition section in pin-fin region decreases under rotating condition, the max Nusselt number tends to appear in the low radius area.
SVM fault diagnosis method based on NMF
Li Jianhong, Jiang Tongmin, He Yuzhu, Jiang Jueyi
2012, 38(12): 1639-1643.
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For overcoming the difficulty of fault feature extraction and solving the low efficiency of fault feature classification in a large dimensions fault diagnosis system,an algorithm of support vector machine(SVM)based on non-negative matrix factorization(NMF)fault diagnosis was researched. It is to avoid the direct feature selection and extraction, to reduce the characteristic dimension,and improve the high-dimensional data feature mode classification speed and accuracy. In order to avoid NMF randomness,characteristics of fault samples dimensionality reduction by training samples coefficient matrix was calculated, so that the consistency of the scale of NMF decomposition times was ensured. The experiment shows that this algorithm can reduce the dimensions of fault feature. The method can enhance the running efficiency and the estimating accuracy.
Wall model for large-eddy simulation based on resonant triad waves
Zhang Nan, Ye Jian, Lu Lipeng
2012, 38(12): 1644-1648.
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Large-eddy simulations (LES)were developed to deal with engineering problems in recent decades. The cost of LES of wall-bounded flows depended strongly on the Reynolds number. Wall models to bypass the wall layer and contain adequate near-wall region kinetics were required to perform high-Reynolds-number LES at a reasonable cost. For this purpose, the wall model based on resonant triads was constructed, which was easier to perform in numerical simulations. The methodologies and key strategies of the model were described and the results of full-developed channel flows show that typical structures of the main flow are reasonable compared with well-resolved examples (without wall-models) and significant first- and second-order statistics are consistent well with well-resolved results.
River simulation based on Poisson disk distribution
Ran Jian, Ding Ying
2012, 38(12): 1649-1652.
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To solve computation overhead problems and to improve plausible visual effects, a novel real-time river-simulating method based on fluid dynamic formula was introduced. A Poisson disk distribution algorithm to achieve a well-structured distribution pattern in screen space was proposed. The algorithm generated distributed particles to depict the river velocity field and to reconstruct the water interface. A texture sprite technique was used to render the river surface efficiently by dynamic accessing and blending to textures. Simulation results show that the presented method can produce a physically plausible flowing river scene and it meets the requirements of real-time simulations.
Sequential compliance test method for lognormal distribution
Deng Qing, Yuan Hongjie
2012, 38(12): 1653-1656.
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Using the experience of sequential verification test program in exponential distribution for reference, the method of making the sequential verification test program in lognormal distribution was discussed, which takes the average life as an indicator. The test procedure of sequential test was provided, and the upper limit value of the producer and consumer risks were studied under censoring. According to the sampling method in practical engineering, the simulation method was proposed to evaluate the above mentioned test program. Evaluation results indicate that the proposed sequential verification test program can meet the requirements of controlling both sides of risk on the premise of satisfying the requirement of sample and censored size. And the consumer’s risk is lower than the expected value.
Detector pose measurement and correction methods for FPD-based cone-beam XCT system
Gao Haidong, Yang Min, Wei Dongbo, Meng Fanyong
2012, 38(12): 1657-1660.
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To eliminate the artifacts in computed tomography (CT) images caused by the flat plane detector (FPD) pose error in cone-beam X-ray CT (XCT) testing system, methods of error measurement and correction were proposed. The ellipse fitting method based on the least squares technique was used to get the detector pose error which is essential for projection coordinate establishing and matching with the reconstruction coordinate accurately. The correction method improves the original Feldkamp (FDK) reconstruction algorithm in the calculation of projection address based on the spatial coordinate transformation theory by which the projection address could be calculated correctly. The methods are of less computation consuming and without hardware calibration. The experimental result proves that the methods could eliminate the artifacts effectively and help reconstruct CT image with high accuracy.
Deadline assignment in real-time cooperative interception of distributed weapons
Sun Yadong, Xing Changfeng, Wu Ling, Lu Faxing
2012, 38(12): 1661-1665.
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In the cooperative interception of distributed weapons, a task is often divided into several subtasks. To ensure the tasks fulfilled in real-time, the overall deadline of a global task was translated into deadlines for subtasks using deadline assignment technique in distributed real-time systems. By building the task scheduling model and simulation model, subtasks with deadlines were scheduled in a simulate way at the precondition that weapon amount is constant while the target amount and the proportion of local load on weapon nodes are changing. According to the results, the performance of different methods on task instantaneity and complete rate was analyzed, which can provide reference for research on cooperation of distributed real-time tasks.
Experimental study on improving AO-resistance of resin using sol-gel method
Yuan Jian, Zhao Xiaohu
2012, 38(12): 1666-1670.
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To improve the atomic oxygen (AO) resistance of the resin in low earth orbit, tetraethyl orthosilicate (TEOS) was added into the epoxy resin(EP) solution. The inorganic phases of SiO2 was in-situ generated using sol-gel method and the SiO2/EP hybrid materials were obtained. The ground-based simulation experiments were carried out to evaluate the AO-resistance of the SiO2/EP hybrid materials. The mass, surface morphology and the surface composition of the samples were compared before and after the AO experiments. The improving mechanism of the AO-resistance was analyzed. There are two essential reasons of the AO-resistance of the hybrid material that the silicones and silica were generated in the resin matrix during sol-gel process and the silica protective coating was formed on the sample surface in AO environment.
Dynamic control of a cable-driven humanoid-shoulder joint based on backstepping technique
You Xianqiang, Chen Weihai, Cui Xiang, Yu Shouqian
2012, 38(12): 1671-1675.
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Aiming at the problems that cable-driven parallel manipulator is difficult to create model and control, the dynamic model of the humanoid-shoulder joint was built by using Lagrange dynamics method so as to obtain the standard form of dynamic equation. Taking into account the redundant actuation and single-direction force for the cable, tension distribution algorithm based on the minimum pre-tightening force was proposed to calculate driving force of each cable. Based on backstepping technique, the control law of the system model was designed for the robot trajectory tracking control problem. The results of simulation show backstepping-based control method is superior in convergence speed, and the driving force of each cable is more than the required minimum tension to keep the cable tensional.
New signal waveforms design for GNSS
Su Chengeng, Guo Shuren, Zhou Hongwei
2012, 38(12): 1676-1681.
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Continuous function waveforms will probably be adopted by future global navigation satellite system(GNSS) signals in bandwidth limitation situation due to their higher spectrum efficiency and better performance. In order to find new signal waveform solution for future GNSS, design criteria of navigation signal waveforms were established, and several waveforms appropriate for future GNSS were explored. The characteristics of traditional and new signals were simulated and compared, code tracking noise, anti-multipath and anti-interference performances were evaluated. It was find that BOCc and MSK applicable to different bandwidths outperform other signal waveforms: BOCc has better performance in wide-band situation, and MSK has better performance in band limit situation; thus the two waveforms were proposed for new generation GNSS signal design.
Novel closed magnetic circuit with permanent magnet biased for giant magnetostrictive actuator
Yang Yuanfei, Zhang Tianli, Jiang Chengbao
2012, 38(12): 1682-1685.
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The magnetic circuit of giant magnetostrictive actuator (GMA) was analysed and optimized with finite element software ANSYS. According to the design goals of high homogeneity of magnetic field and low magnetic flux leakage, a novel magnetic circuit biased by the combination of built-in permanent magnets was proposed in the base of compensation principle of dual-permanent magnets with contrary polarity. Magnetic field along the direction of the length of giant magnetostrictive rod was homogeneous, while well-closed magnetic circuits were informed in both biased magnetic field and driving magnetic field. According to the results from ANSYS analysis, the unevenness of the bias magnetic field and driving magnetic field is 3.51% and 8.73% respectively, which are less than 10%. The total magnetic leakage in the specified location (7 cm from the GMA) is 30.4 A/m , meeting the standard of practical application(<80 A/m).
Emulator-based embedded software unit testing method
Xu Fu, Jin Maozhong, Liu Hui, Chen Qi
2012, 38(12): 1686-1690.
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A unit testing method for embedded software was presented, which used customized linker to parse object files and generates memory image. The memory image can be loaded into a software simulator to generate testing results. This method is especially useful for the unit testing of embedded software, which can test incomplete code and support designing stub functions and test cases through advanced script programming language instead of embedded assembly programming language. Then the training cost of testing engineers can be reduced. The application result from one institute of China Aerospace Science and Industry Group shows that it can improve the efficiency of embedded software unit testing significantly.

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