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2011 Vol. 37, No. 9

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Harmonic analysis and optimized vibration sensor locations of the helicopter intermediate gearbox
Su Xunwen, Wang Shaoping, Zhu Dongmei, Shi Jian
2011, 37(9): 1049-1053.
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Multi-freedom vibration model has been studied. A methodology of optimized vibration sensor location, in which the amplitude was sensitive to fault frequency, was presented. First, a finite element model of the helicopter intermediate gearbox was constructed, then a signal stimulus was forced to the gearbox of the model by the method of harmonic analysis. The study shows that different locations have clear different amplitudes according to the signal stimulus. So the location, where the amplitude was the largest, should be the best sensor location and a function of optimized sensor locations was presented. This optimized sensor location methodology is also applicable to other parts of the helicopter transmission and other rotating mechanics.
Attitude control of quadrotor aircraft via nonlinear PID
Su Jingya, Fan Penghui, Cai Kaiyuan
2011, 37(9): 1054-1058.
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Based on the nonlinear attitude dynamic and kinematic model of a quadrotor aircraft, an almost globally stabilizing nonlinear proportional integral derivative(PID) attitude controller was developed. The proposed controller consists of a linear PID feedback and a compensation of inertia torques, and can reject the external disturbances consisting of not only a constant term but also a bounded and square-integrable term. Simulation results show the effectiveness on disturbances rejection. Experiments of set-point attitude control were conducted on the constructed attitude control platform. Experimental results illustrate that the pitch and roll angular errors are both smaller than one degree, which verifies the effectiveness of the proposed controller on small angle maneuvers and the robustness against unmodeled dynamics.
Phase coding technology used in MIMO-CDMA system
Wang Xuesong, Yang Xing, Xue Chunmei, Li Daoben
2011, 37(9): 1059-1062,1069.
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In non-rich scattering propagation environment due to lack of angular spreading, non-uniform distribution of singular values of multiple in multiple out(MIMO) system transmission matrix causes a degradation of system capacity. To solve this problem a technology called phase coding was proposed. Phase coding transformed original singular channel transmission matrix to the non-singular matrix by creating multi-path deliberately. Distribution of transmission matrix singular values was improved and system capacity was improved as well. Using phase coding MIMO technology can be applied in the flat fading channel environment which has a very strong spatial correlation. So the application range of MIMO technology is expanded. Furthermore, MIMO channel can be transformed into parallel sub-channels without pre-coding at transmitter and feedback channel information from receiver, so system complexity is reduced. First theoretical analysis and basic principle of phase coding was discussed, followed with simulation results which verify theoretical analysis.
New attitude determination algorithm for single epoch, single frequency using GPS
Qin Honglei, Chen Wantong, Jin Tian, Cong Li
2011, 37(9): 1063-1069.
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The LAMBDA method needs to start with a float solution to the ambiguities, and several epochs are needed by only using phase measurements and it will take a long initial time. To deal this problem, with the special transformation of global positioning system (GPS) carrier phase single difference observation equation of short baseline, new observation equations in which the unknown integer ambiguities are treated as noise could be obtained. Combining them with the original equations, it is possible to get a float solution using only one epoch for that the equations have redundancy. And it changes that the floating solution can not be obtained in a single epoch by only using double difference phase observation equation. In-depth study through the float solution and fixed solution from the LAMBDA algorithm, a new method which can fix the low precise float ambiguity to the correct integer ambiguity was given. It reduces the dependency of the high precise float resolution for LAMBDA method which needs many epochs to obtain, so the integer ambiguities can be estimated in single epoch and single frequency. The success rate is more than 97% in actual testing. The results show that the new method can be effectively used for real-time calculation of kinematic attitude.
Experiment and analysis for cold charging process of new energy storage device
Chi Pengtao, Xie Yongqi, Yu Jianzu, Yang Xianning
2011, 37(9): 1070-1075.
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The heat transfer enhancement effect of the metal foam has been verified by dozens of researches. In order to test the cold charging effect, a new type of high-efficiency energy storage devices was made up by composite phase change material(PCM), which was consisted of copper foam (the heat transfer enhancement) and water. Via experimental study, the heat preservation effect of the devices in the refrigeration equipments was simulated. The model was set up and calculated through quasi-stable state method, and the results meet the test results very well. The cold charging process of the new type energy storage devices was approved to be faster and more adequate compared to the traditional energy storage devices. The entire heat transfer velocity and energy storage efficiency are obviously improved, which promises a good prospect in the refrigerated transportation.
Analysis on composite hydraulic servo control system with dual independent closed-loop
An Gaocheng, Chen Juan, Fu Yongling, Qi Xiaoye
2011, 37(9): 1076-1080.
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In view of the existing hydraulic servo control systems- advantages and disadvantages, a new composite hydraulic servo control system with dual independent closed-loop based on servo motor, definite displacement pump, accumulator and servo valves was put forward with the trend of high performance and energy-saving. Its structural characteristics were analyzed, and the mathematical model was made. The simulation analysis and experiments have shown that it can fulfill the performance of each control component and achieve the flow adaptation. Comparing with the existing control scheme, the new control system is simple, reliable and has made great improvement in comprehensive indicators, and is fit for airborne hydraulic system and missile hydraulic system.
Mechanical parameters reverse estimation of lunar soil and experimental verification
Li Meng, Gao Feng, Sun Peng, Cui Ying
2011, 37(9): 1081-1085.
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In order to predict and control the traction trafficability of a lunar rover, an algorithm for mechanical parameters estimation of lunar soil based on linear-least squares method was presented to estimate two key mechanical parameters, i.e., internal cohesion and internal friction angle. The improved wheel-soil interaction model for lugged rigid wheel which considering the effect of wheel lugs on stress distribution was simplified; An algorithm was thus created to calculate internal cohesion and internal friction angle of the soil. Experimental data of wheel-soil interaction were imported into Matlab programs to estimate cohesion and internal friction angle of lunar soil simulant, and the estimated values are close to the measured values of lunar soil stimulant. The results of experimental verification indicate that the algorithm is accurate and effective, moreover, the algorithm also shows good stability and high arithmetic speed, which allows a lunar rover to estimate mechanical parameters of the lunar soil on site.
Parser of industrial Ethernet EtherCAT based on XML
Liu Zhe, Huan Ji, Liu Yanqiang
2011, 37(9): 1086-1090.
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The technology and realization method of industrial Ethernet EtherCAT parser based on extensible markup language(XML) were studied. The format of EtherCAT datagram was introduced. The structure of Ethernet probe and parser was analyzed. A method of protocol datagram description based on XML was proposed to deal with the problem that common Ethernet parsers are limitative in the applications of industrial Ethernet. Then an open and reconfigurable industrial Ethernet parser was designed. Performance test of the method of protocol datagram description and open parser was carried out. The implementation shows that the method of protocol datagram description based on XML can describe EtherCAT datagram clearly, and the open industrial Ethernet parser can parser EtherCAT datas. Users can define, modify and extend parsing rules according to the protocol object format, and obtain clear display of the protocol telegram.
Effects of propellants temperature in gas-gas injector inleton combustion performance and wall temperature
Li Mao, Gao Yushan, Jin Ping, Cai Guobiao
2011, 37(9): 1091-1094,1099.
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A combustor with a shear tricoaxial gas-gas injector was researched numerically and experimentally. The influence of propellants temperature in the injector inlet on the combustion performance and wall temperature was investigated and analyzed. The numerical simulation results show that the variable momentum ratio of fuel to oxidizer which brought by the variable propellants temperature is the main factor. The influence of the fuel temperature on the combustion performance and wall temperature is more obviously than the oxidizer temperature. The experimental results validate the numerical simulation results.
LES/RANS hybrid method for supersonic axisymmetric base flow
Gao Ruize, Yan Chao
2011, 37(9): 1095-1099.
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To overcome the limitation of large eddy simulation(LES) for wall problem, LES/RANS hybrid method was investigated in recent years,which not only combined the advantages of LES and RANS but also avoided the disadvantages of each other. Base flow is a difficult problem in CFD. Based on LES/RANS hybrid method, Smagorinsky-BL model and a new Vreman-BL model were applied to an axisymmetric base flow at supersonic conditions. The obtained base flow structure was analyzed in comparison with experimental data. The results show that predictions of velocity, pressure distribution, velocity and pressure distributions of base flows using hybrid method compare well with experimental data.
ESD damage simulation of integrated circuits by the consideration on parasitic parameters
Lü Weimin, Hu Dong, Ma Jinghua, Xie Jinsong
2011, 37(9): 1100-1104.
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In the traditional electro-static discharge (ESD) damage simulation based on logic circuit, the influence of layout was not taken into account as usual, and there was larger deviation between the results of simulation and the actual damage, so a new simulation method of ESD damage for integrated circuits was presented by the consideration for parasitic parameters extraction in layout. Firstly the specific simulation process in the application was given. Then the models of kinds of parasitic were defined according to empirical parameter extraction method. Lastly the ESD damage simulation for integrated operational amplifier LM741 as case study was carried out. According to zap test, failure location and electrical performance testing, the results showed have much consistency in simulation and experiment, and the validity of the simulation method is finally verified.
Synthetic design on maneuver processes and flight loads of fighters
Cao Qikai
2011, 37(9): 1105-1109.
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The integrated design of maneuver processes and flight loads was investigated for modern fighters. The aeroelastic correction of fight loads and maneuver processes, and maneuver load alleviation were further studied. It indicates that the influences of structural deformation on elastic aerodynamic loads and maneuver processes are significant, and the maneuver loads can be availably alleviated using modern control technique. The investigation of this work can be applied in analysis and study on the maneuver processes and flight loads for the modern fighters.
Dynamical modeling and simulation of rigid-flexible hybrids in large overall motions
Ge Qingming, Guo Jun
2011, 37(9): 1110-1114.
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The coupling dynamics study of spacial flexible structures that takes the coupling efforts into account is of great importance in aerospace field. The flexible structures were discretized by means of finite element method(FEM), and modal matrix of the flexible structures was obtained. The dynamical model of rigid-flexible hybrids in large overall motions was established based on the theory of modal superposition method and Kane equations. And then, the equations were solved througth Matlab programming. The validity of dynamical model and Matlab programming was verified by comparision of the results of Matlab simulation and business-software simulation. This research solves dynamical simulation of the spacecraft composed of rigid central body and flexible appendages.
Real-time programming method for flight path of unmanned vehicle based on dynamic RCS
Yan Qing, Xiong Junjiang, You Siming
2011, 37(9): 1115-1121.
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Simplified radar detection models are applied in conventional flight path programming of unmanned vehicle, in which only the distance between unmanned vehicle and radar has been taken into account, but the dynamic variation of radar cross-section (RCS) with attitude angle of unmanned vehicle has not been considered. New dynamic RCS model was presented to characterize the RCS distribution nature of unmanned vehicle, radar-s detection probability model was developed to involve dynamic RCS and the distance between radar and unmanned vehicle. From genetic algorithm (GA) and dynamic RCS, real-time programming for flight path of unmanned vehicle was conducted and compared with conventional models. From verification examples, it is demonstrated that the models presented are feasible and valid to avoid the detection of radar.
Requirement of ACN and tire press for future large transporter based on allowable load of present airport pavement
Cai Liangcai, Wu Aihong, Li Guangyuan, Li Tianmin
2011, 37(9): 1122-1126.
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In order to make the future large transporter adapt to allowable load of present airport pavement-s requirement, after a great lot of investigations on pavement structure’s type, thickness, allowable load and maximal tire press accepted, advisory value of aircraft classification number(ACN)and tire press of future large aircraft was given. A 3-D finite element model which had nine slabs was established, the mechanical responses of cement concrete pavement was analyzed with advisory ACN and tire press under single wheel and main landing gear of IL-76, C-5. With the aim to reconstruct present airports as little as possible, the ACN between 16.1 and 24.2 and tire press under 0.80 MPa is reasonable for future large transporter. Allowable load of present airport pavement can ensure the future large transporter operate normally on 50 percent of present airports without reconstructing.
Impact analysis of targets’ surface to beat-frequency signal in FMCW laser radar
Yang Dezhao, Song Ningfang, Lin Zhili, Ou Pan
2011, 37(9): 1127-1131.
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The characteristics of beat-frequency signal and the accuracy of range and velocity measurement in frequency modulated continuous-wave (FMCW) coherent laser radar were influenced by the surface roughness of measured target. In order to estimate the impact and improve the system-s performance, the scattering surface was spatially discretized into many patches, and the electric field intensity model was built and analyzed. Monte Carlo simulations and system experiments were carried out for the cases with different roughness surfaces. The results indicate that the alternating component of beat-frequency signal will decrease dramatically with the tilt of mirror plane, and when the surface is Gaussian roughness plane, it has a negative exponential relationship with the ratio of the surface-roughness height to the square of light wavelength. The experimental results are consistent with the theoretical analysis and numerical simulation results, and the system-s range-measurement error is less than 1mm, the static velocity stability is better than 0.1mm/s.
Adaptive parallel simulated annealing genetic algorithms based on cloud models
Dong Lili, Gong Guanghong, Li Ni, Sun Yong
2011, 37(9): 1132-1136.
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Due to the shortcomings of genetic algorithms such as the low convergence rate and premature convergence, an improved genetic algorithms was proposed, called adaptive parallel simulated annealing genetic algorithms based on cloud models (PCASAGA). PCASAGA applied cloud models to the adaptive regulation of the crossover probability and mutation probability. Simulated annealing was combined to prevent genetic algorithms from local optimum. Multi-species optimization mechanism was used to realize algorithm parallel operation. Intel-s threading building blocks (TBB) parallel technology was also used to realize algorithm parallel execution on multi-core computers. Theoretical analysis and simulation results verify that PCASAGA has better convergence speed and optimal results than original or improved genetic algorithms, and it takes full advantage of the current computers multi-core resources.
Building extended spirality searching model of dipping sonar of anti-submarine airplane
Wu Fang, Wu Ming, Yang Rijie
2011, 37(9): 1137-1141.
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Based on the omnidirectional moving submarine targets, and the actual searching prcess of anti-submarine airplane, the wind factor affeacting searching prcess was analyzed. Extended spirality searching model of dipping sonar and submarine moving models were built. According to the models of active/passive dipping sonar, searching ranges of active/passive dipping sonar were discussed. In the factor of given ocean environment, experimental results simulated and analyzed the extended spirality searching course of dipping sonar, and searching ranges of dipping sonar for different target strengthesand emission frequency. The experimentation compared and analyzed the influence of the varieties of seaching range of dipping sonar, submarine moving manners on extended square, extended circle and extended spirality searching manners. The experimental results indicate that the search efficiency of extended spirality searching manner of dipping sonar is better than extended square and extended circle.
Reliability analysis method based on adaptive importance sampling
Ma Jiming, Zhan Xiaoyan, Zeng Shengkui
2011, 37(9): 1142-1146,1150.
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Low efficiency and accuracy problem is serious when analyzing the rare event using Monte Carlo methods, a reliability analysis method was proposed based on the adaptive importance sampling (AIS). Finding the failure points is difficult when the failure equation is not explicit. Firstly a conditioned recursion algorithm was used to search the failure point which was as close as possible to failure surface. Then the failure point was selected as the new sample center, and the center point was adjusted iteratively to get a failure sample nearby the design point. The failure sample was used to predict the parameters of importance sampling density function; iteration will be performed during the process until the deviation of failure probability met the requirement. Finally, two typical cases were used to verify the method; simulation results show that the failure point can be searched quickly through simulation method without an explicit failure equation, which means it is applicable to the situation where failure equation is implicit. Comparison results with Monte Carlo methods prove that simulation efficiency is increased obviously, especially for the application condition with very small failure probability.
Rotor damping analysis based on helicopter dynamic requirement with rotor/fuselage coupling
Guo Junxian, Xiang Jinwu, Qin Haiying
2011, 37(9): 1147-1150.
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The rotor damping is one of the key points for a helicopter dynamic design. An introduction to the theoretical and practical study of one of the helicopter dynamic problems, which describesd the development of the rotor damping based on the helicopter dynamic with rotor/fuselage coupling that contains the stability analysis of ground resonance and the stability of rotor/power/transmission coherent was given. Based on the dynamic requirement of rotor/frame, damping analysis of the elasto-damper and the fluid-damper, which considered the effect of the stiffness and the damping was presented. The parametric sensitivity of the damper stiffness and damping was estimated. With constraints from engine control and ground resonance, the different effect was given with various available designs.Calculating and testing results performed demonstrating that, as solution to the dynamic problem, the damping with suitable orifice design for a variable liquid damper is reasonable for the helicopter dynamic problem solution and rotor blade folding.
Modeling and analyzing for testability of hierarchy systembased on multi-signal flow graph model
Lü Xiaoming, Huang Kaoli, Lian Guangyao
2011, 37(9): 1151-1155.
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In order to make analysis for testability of hierarchy system, a testability modeling and analyzing approach were proposed for hierarchy system based on multi-signal flow graph (MSFG). This approach can used MSFG to build hierarchy system-s hierarchy structural mode. Firstly, dependency model was applied to make testability analysis for the top-model. If the hierarchy module can-t be isolated with other modules, the dependency model was used to make testability analysis for the ambiguity again, continuing this process until realizing diagnostic designing of the whole hierarchy system. Finally, by applying the proposed approach in some hierarchy structural amplifier/filter system, the efficiency of this method was verified, and the result shows that this method is efficient, and effective diagnostic strategy can be obtained for the testability analysis of hierarchy system.
Three analysis models of torsional frequency of stiffening cylindrical shell
Pan Zhongwen, Xing Yufeng, Yang Yang
2011, 37(9): 1156-1159.
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For simplifying the analysis of stiffening cylindrical shell in rocket, the computational method of torsional rigidity in the area-equivalence method was studied for the stringers in stiffening cylindrical shell, it is shown that the effect of stringers on the torsional rigidity of stiffening cylindrical shell is negligible. The equivalent beam or shell model with uniform thickness, the equivalent shell model with varied thickness and three dimensional (3-D) beam-shell model were proposed to solve the inherent torsional vibration frequency, and the features of these models were discussed. It was theoretically revealed that the obtained equivalent thickness by the area-equivalence method could not be directly used to calculate the torsional rigidity. Two modification methods, namely, the rigidity reduction method and frequency modified method, were presented when the equivalent thickness was directly utilized to solve the torsional frequencies. Numerical comparisons validate the proposed methods and models.
Allocation mechanism of military aircraft spares based on PHM
Mao Deyao, Zhou Dong, Wen Peiqian, Lü Chuan
2011, 37(9): 1160-1164.
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The existing allocation model of military aircraft spares can-t meet the allocation of military aircraft spares based on prognostics and health management (PHM). First,the generation process of military aircraft spares demand and the existing allocation model of military aircraft spares were formulated. And on the base of under-built PHM system, analyses the effects of PHM on military aircraft spares allocation were analysed. Then, the spares allocation mode based on PHM was given. Last, the organizational-level spares allocation mechanism frame was built by use of the PHM system, the rear sustaining support base spares allocation mechanism frame was built by use of the automatic logistics information system and virtual inventory theory, and the information share theory was used to build the unite pooling spares allocation mechanism frame. This allocation mechanism can provide guidable and executive reference of spares allocation for the PHM technology gradually being applied on military aircrafts.
Modeling and control for hydraulic nonholonomic constraint transmission system
Wang Yan, Dong Hongkang
2011, 37(9): 1165-1168,1175.
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Nonholonomic constraint transmission (NCT) is currently driven by a motor, which leads NCT complex and expensive. In the closed hydraulic system composed of concatenate variable pumps, liquid flows continuously and the pump rotate speed is inversely proportional to its displacement. The pump rotate speed can be adjusted by changing its displacement and according to this theory, hydraulic nonholonomic constraint transmission system (HNCTS) was proposed for Cobot. HNCTS had many merits, such as fast response, load stiffness and so on. The mathematical model of 2-DOF plane Cobot based on HNCTS was built for simulation. The fuzzy control algorithm, one input and two outputs, was introduced to control HNCTS. The validity of HNCTS was proved by simulations. Simulation results show that the HNCTS can be decoupling controlled by fuzzy control algorithm, and the HNCTS has the ability to achieve passive constrained control and desired trajectory tracking for Cobot.
Airport concrete pavement design for large aircraft in future
Wu Aihong, Cai Liangcai, Gu Qiangkang, Li Guangyuan
2011, 37(9): 1169-1175.
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The present concrete pavement design specification uses design aircraft to convert the traffic of other aircrafts into traffic of design aircraft according to the principle of equivalent damage, and it assumes that the wheel path in the lane of runway follows uniform distribution. Actually, wheel path follows the normal school, landing gear of new large aircraft becomes more complex, the peak value of cumulative damage of each aircraft maybe not at the same location, shortages of conversion method using design aircraft is increasing. Based on the wheel path in the lane of runway follows the normal school, pass-to-coverage ratio is used to calculate passes number. Design aircraft-s function is replaced by cumulative fatigue damage of pavement structure, which produced by all kinds of aircrafts is carried out directly. A new design method for concrete pavement based on cumulative fatigue damage is discussed and a design example is given. It is approved that the pavement design method using cumulative fatigue damage as design index is more suitable for concrete pavement design of large aircraft with complex landing gear.
Fast cavity-mode algorithm for analysis of radiation of power bus
Cao Cheng, Su Donglin, Dai Fei, Gao Wanfeng
2011, 37(9): 1176-1180.
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It is very complicated to analyze the power-bus structure of the printed board circuit(PCB). Cavity-mode method is an effective way to analyze the power-bus structure of the printed board circuit, however, the algorithm is hard to converge. Therefore, the total computing time of the algorithm to analyze the power-bus of PCB is long. And the method is not applied to compute the radiation field of the structure. Based on the method, a fast cavity-mode algorithm was presented for analyzing the radiation emission problem of the power-bus structures in PCB design. In this method, the double series summation cavity-mode expression which is used to get the far-field characteristic of a parallel plane structures is simplified for using a Cauchy contour integration. The working condition of the method was deduced in our work. The convergence of the fast algorithm was obtained either. It is shown that this fast method is more efficient than the convention cavity-mode method for the small computation time, the high convergence and the same accuracy. Simple examples were analyzed to validate the proposed formulation.
Panoramas subspace based scale invariant feature tracking method
Fan Zhiqiang
2011, 37(9): 1181-1185.
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Aiming to panoramas images, a panoramas subspace based scale invariant feature tracking method was proposed which contains an offline process to build feature correspondence between panoramas and original image sequence and an online process to match features based on keyframe recognization. Firstly making full use of the ability of panoramas to cover approximately entire local nature space, a way was given to extend Kd tree to build feature correspondence between panoramas and original image sequence which can efficiently reduce feature redundancy of panoramas and improve the first matching stage-s time. On the basis of this mapping, a voting method was used to recognize keyframe to finish the second matching stage. Through the two feature matching stages above, the aim was reached that converts the feature matching from multiple images to single image to decrease feature number. Experimental results show that the method can efficiently achieve good balance between matching time and stability.
Mechanism of anodizing oxidation film of AZ91D magnesium alloy at low AC voltage
Li Wen, Li Weiping, Liu Huicong, Zhu Liqun
2011, 37(9): 1186-1190.
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A new anodizing process at low AC voltage (10 V) was used to prepare an electrochemical anodized film on AZ91D magnesium alloy in the electrolyte containing NaOH and Na2SiO3. A scanning electron microscope (SEM) with an energy dispersive X-ray spectroscopy (EDS) system was used to study the characteristics of the film-forming and growth process of the anodizing oxidation film on the AZ91D magnesium alloy. The influence of the parameters of oxidation process on film growth process and the properties of the film were also investigated by using an X-ray diffractometer (XRD) and electrochemical analyzer. It is found that the oxidation film on the AZ91D magnesium is even, non-porous and flat-shape. The growth process of oxidation film show superposition-type and the phase composition of the oxidation film is mainly Mg2SiO4. In addition, the corrosion resistance of anodic film on the AZ91D magnesium alloy is superior to the blank sample in 3.5%(mass fraction)NaCl solution.

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