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2010 Vol. 36, No. 9

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Calculating method for matching enthalpy parameter of four-wheel-bootstrap refrigeration system for civil aircraft
Zhang Xingjuan, Li Feng, Yang Chunxin
2010, 36(9): 1009-1012.
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The foreign advanced civil airplane cabin refrigeration system has been developed from three-wheel-bootstrap to four-wheel-bootstrap high pressure water-separation system. The traditional method used for matching the system thermal parameters was complicated. A new model for calculating the enthalpy parameters was proposed and used for the matching calculation. The gas flow ratio, fan power ratio and the turbine power ratio were introduced and their effect on system performance was analyzed. The results show that the use of enthalpy instead of temperature as the state parameter of the system accessories is of a clear physical concept, and can be easily programmed and avoid double counting of the saturated humidity of the connection points between accessories, and can also simplify the heat exchanger thermodynamic calculation and reduce the iteration times of the system. The results can provide a theoretical guidance for civil aircraft researches.
Flow and heat transfer in the complex passages of turbine blade trailing edge
Deng Hongwu, Tan Yan, Wang Jiaren, Luo Xiang
2010, 36(9): 1013-1016.
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Experimental method was used to study the characteristics of heat transfer and flow resistance in turbine blade trailing edge complex passages. This experiment use vapor heating method, and this method could make the experimental model have equivalent wall temperature boundary condition. The experiment models conduct the structure of the pin-fin arrays, micro channels and the diaphragm plate. The pin-fin arrays, micro-channels and the rectangular diaphragm plate, the waved diaphragm plate diaphragm plate were respectively combined. The outside wall was divided into ten regions to get the local heat transfer coefficient. When the Re was 10000~60000, the results shows that the structure with the worst general heat transfer performance is rectangular diaphragm plate plus optical channel, the structure with the best general heat transfer performance is the waved diaphragm plate plus micro-channels.
Fast PN code acquisition for satellite spread spectrum transponder
Feng Wenquan, Zhang Dezhi
2010, 36(9): 1017-1020.
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Large Doppler offsets are inherent to direct spread spectrum signal due to high dynamic environment in low earth orbit satellite communication scenarios. Frequency offset can be dozens of kilohertz, which cause traditional acquisition approach failed to complete PN code acquisition. A part-coherent combined with FFT technique was proposed for this problem. It utilized fast Fourier transform(FFT) to compensate coherent loss resulted by frequency shifts. It simultaneously searched code phases and got Doppler offsets, thus acquisition time could be significantly reduced. Acquisition structure was given, and FFT compensate performance was analyzed. The selection of part-coherent parameters and FFT points were given. Auto adaptive threshold technical was used to realize code acquisition when input signal power varied widely. Theoretical analysis and simulation results verify that the approach can complete fast code acquisition in high Doppler shift and low signal to noise ratio environment, and take up fewer field programmable gate arrays resources.
Aircraft collision risk assessment at intersecting air routes
Meng Xiangwei, Zhang Ping, Wang Ying
2010, 36(9): 1021-1025.
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After compared with the classical Reich modal, improvements was made on an event-based aircraft collision risk model at intercepting routes, the collision risk due to possible vertical relative movement was counted for aircraft in straight and level flight. The possible reason why the horizontal collision probability derived by the event model was excessively conservative than the Reich model was analyzed. The aircraft relative position error data were generated using Monte-Carlo simulation and fitted to several probability distributions, their effects on aircraft collision risk were compared. The result shows that it is the tail data representing the gross error that decide the aircraft collision risk and no distribution functions except generalized Pareto distribution can fit the tail data well due to less amount of gross error data.
Rail wear measurement method based on structured-light vision
Sun Junhua, Wang Weihua, Liu Zhen, Zhang Guangjun
2010, 36(9): 1026-1029.
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The principle of rail wear measurement based on structured-light vision was analyzed. A method for dynamically measuring rail wears in vehicle-mounted was proposed. The structured-light vision sensor was installed at the bottom of the train, and the section profile of the rail was measured. Taking rail waist as measurement benchmark, the rotation matrix and translation vector between light-plane coordinate frame and designed coordinate frame were estimated by iterative closest point (ICP) algorithm, then, the rail waist profile was registered to designed profile, based on which the rail wears were calculated. Compared with previous methods, the proposed method does not need a specially vision sensor to measure the benchmark. Benchmark measurement and wear measurement are achieved with one same vision sensor. System cost is effectively reduced, and it is operable. Measurement accuracy is also guaranteed due to no need of global calibration of multi-sensor. The experimental results show that the repeatability precision of the method is high.
Method for investigation of the optimal redundant gyros number based on reliability analysis
Fu Li, Wang Xinling, Yue Yazhou
2010, 36(9): 1030-1033.
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To solve redundant gyros configuration problem of the strapdown inertial navigation system with redundancy technique in sensor level, a method to determine the optimal number of gyros that compose the redundant system was proposed with a view to the system reliability and cost. It was assumed that the fault of each gyro should be independent of others. To obtain the optimal gyros number, a new criterion was developed by proposing reliability function and the number making the criterion value come to maximum is the optimal gyros number. The change of criterion value was analyzed when the gyros number of redundant system was different. The results show that the redundant system reliability increases with the gyro number increasing. The system reliability improvement is limited but the cost of system increases greatly from some number of gyros. Finally, the optimal gyros number of redundant configuration is given and it is 6.
Rotor icing model and trim characteristics analysis for tandem helicopter
Li Guozhi, Cao Yihua, Zhong Guo
2010, 36(9): 1034-1037.
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A theoretical rotor icing model was proposed based on the computational fluid dynamics (CFD) technique to study the tandem rotor helicopter dynamics due to icing. Considering the rotor blade ice shedding and local temperature variation on the rotor blade, another engineering rotor icing model was advanced based on the rotor icing tunnel data. The model of the tandem rotor helicopter dynamics due to icing was built and the trim characteristics of CH-47B due to icing at the hover and in the forward flight were analyzed. The effect on the rotor torque due to temperature, icing time, liquid water content and median volumetric diameter in the icing condition was computed. The agreement between the theoretical rotor icing model and the engineering method indicates that the models are feasible and effective, and they can lay the foundation of the research about the tandem helicopter dynamics in the icing condition.
Lateral-directional control of tailless aircraft with multiple control surfaces
Feng Lihao, Wang Jinjun, Yu Dongsheng
2010, 36(9): 1038-1042.
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The influence of control surfaces deflection on lateral-directional characteristics of a tailless aircraft with multiple control surfaces was investigated in a wind tunnel using force measurement. Both single deflection and simultaneous deflection of elevons and flaperons have a good effect of lift increment, while all-moving tips (AMTs) deflection leads to a reduction in lift before stall. The influence law of control surfaces deflection on the yawing moment control is not significant. However, single deflection of the AMT has a better effect on the yawing moment control than elevons and flaperons. Both single positive deflection and simultaneous positive deflection of elevons and flaperons result in a negative rolling moment, and the increment is much more significant with a larger deflection angle. Elevons have a better effect on the rolling moment control than flaperons, while AMTs have little influence on the rolling moment control. Besides, the control efficiency can be improved obviously adopting simultaneous deflection compared with single deflection.
Semantic security algorithm for wireless sensor network
Kang Yimei, Wang Tao, Hu Jiang, Zhao Lei
2010, 36(9): 1043-1047.
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To improve security of communication data in WSN (Wireless Sensor Networks), a semantic security algorithm based on a changing mapping table was presented. Considering of threshold-sensitive characteristics of WSN application, a data collection method with variable precision was used, i.e. high collection precision close to threshold and low collection precision far from threshold. Then a mapping table was introduced which defined the mapping way of identification and original semantic. The encryption in the nodes and decrypt in the gateway were depended on the mapping table, which kept synchronization between the gateway and the node during the communication. To enhance security, the mapping table was continuously updated based on a random changing factor. And some improved random number generators were suggested in order to improve the nonlinear feature of mapping table conversion. The time complexity analysis, space complexity analysis and energy consumption analysis were given. Finally, some experiments were done with Micaz sensor nodes and the simulation results and analysis were given.
Simulation and flight test of trajectory in terminal guidance
Xi Shenghai, Xiang Jinwu
2010, 36(9): 1048-1051.
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A method of simulation and flight test for seeker-s particular trajectory in terminal guidance was presented. In the flight simulation of trajectory in terminal guidance, height decrease by the entry maneuver need to be achievably small, and precision request of tracking in the diving flight phase should be satisfied. A set of nonlinear 6-DOF equations was used, in which the coupling between longitude and lateral motion was considered. To keep precise tracking in the diving and flight security with large magnitude of flight speed, dive angle, height altering, 3 types of stick roll control were analyzed, and control scheme satisfies request of precision was given. In the entry phase, bank angle was firstly changed to 180°. After satisfying dive angle of the trajectory by elevator control, bank angle returned to 0°. Flight test project was accomplished to verify the reliability and availability of the control scheme. Results of flight simulation and test show that the method presented could improve flight test efficiency and the precision of aircraft tracking particular trajectory with guaranteed flight security.
Object-oriented method for virtual organization integrated modeling
Tang Wenzhong, Qin Jingyi
2010, 36(9): 1052-1056.
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These integrated modeling methods named virtual organization integrated modeling(VOIM) were discussed, which can be used for agile virtual organizations process dynamic optimization. These methods were integrated by unified modeling language(UML), the methodologies of integration definition for function modeling(IDEF0) and event-driven process chain(EPC). The combination of these methods means that the weaknesses of each can be counteracted by the strengths of others. These methods were proved to be very good means of modeling and optimization in complex systems, especially in virtual organization, in which IDEF0 modeling the function view of virtual organization, EPC refining the function view, and UML combining the various views of the virtual organization through the entities mapping relationship. It is conducive to achieving the system-s modularity and the reusability of the model. The translation from UML to EPC was discussed. Finally, the models were described formally, consequently made the syntax and semantics of VOIM defined strictly, and provided a good foundation for validation and simulation.
Optimal of initial spares scenario in civil aviation
Xiao Boping, Kang Rui, Wang Naichao
2010, 36(9): 1057-1061.
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To meet the requirements that airline depresses initial spares cost and increases the airplane-s utilization, maximum marginal utility based optimal methods for initial spares scenario was presented. By the algorithm of Poisson distribution, items spare scenarios could be given only when the support probabilities were known. The defect of this method was that the spares scenarios may be not optimal. In order to solve this problem, the optimal model and implementing process of marginal analysis were presented, and then the spares- numbers of all parts in the item list were calculated at the same time. The initial spares scenario case was optimized by spare optimal software in the condition that either spares cost was invariable or operational availability was invariable. Cost-efficiency curves were drawn and datasheets of two optimal scenarios were got. The increase of operational availability and decrease of spares cost were discovered by comparison of data in the cost-efficiency curve. And so, the trend of spare number change was also seen by analysis of datasheets. The result shows that the optimal algorithm has wide application in initial spares scenario optimization of civil aviation.
Structural optimization of flexible aircraft considering aileron efficiency based on experimental aerodynamic forces
Shao Ke, Wan Zhiqiang, Yang Chao, Zhang Bocheng
2010, 36(9): 1062-1066.
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Wing-s structural optimization of a flexible aircraft was conducted to solve aileron reversal problem utilizing a genetic algorithm. The aileron efficiencies and rates of roll of the aircraft were calculated using nonlinear experimental aerodynamic forces. The emphasis research was wing-s structural optimization to a serious flight state which contained the aileron reversal problem. The variations of aileron efficiency and angular velocity of rolling with dynamic pressures were investigated separately based on the aircraft structure before and after the optimization. The flutter characteristics of the aircraft before and after the structural optimization were contrasted. The optimizations to different flight states and a synthesized optimization considering constraints of three different flight states were developed. The affection of angle of attack to the optimization was analyzed. The results show the aileron reversal can be solved using structural optimization in the detailed design phase of the aircraft, and the optimization has no negative effect on the flutter characteristics of the aircraft.
Application of Gap criterion in prediction of category Ⅱ PIO
Meng Jie, Xu Haojun, Li Dawei, Zhang Jiankang
2010, 36(9): 1067-1070.
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To solve advanced fighter flight safety problem caused by category Ⅱ PIO (pilot induced oscillations), the Gap criterion was applied to predict category Ⅱ longitudinal PIO. The sinusoidal input/triangle output describing function model of rate limiting was built and the Neal-Smith pilot model was improved. The describing function method was proposed to investigate the mechanism of category Ⅱ PIO. The stability formula of nonlinear pilot-vehicle system was derived. The calculation method of Gap criterion was attained. The category Ⅱ longitudinal PIO sensitivity of a certain fighter was predicted by Gap criterion and the results were verified by time domain simulation. The results prove that Gap criterion has specific physical significance and illustrative results, calculate efficiently, and can predict the occurrence of category Ⅱ PIO accurately. The important theoretical references can be provided for designing flight control systems of advanced fighter.
New interface boundary condition method for coupled thermal simulations
Li Pengfei, Wu Songping
2010, 36(9): 1071-1074.
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A new interface boundary condition method was advanced for coupling between hypersonic flow field and structural heat transfer. The new coupling scheme consisted of solving an additional partial differential equation on the interface, which was derived from the Dirichlet and Neumann conditions at the interface. The interface solution was explicitly influenced by the two subdomains. The Godunov-Ryabenkii method was used to analyze the stability properties of the method. The analysis indicats that the method is not only more stable but also more accurate than the conventional method. The method proposed is applied for aerodynamically infinite column. The transformation of column-s temperature is detailedly analyzed during pneumatic heat.
Dexterity optimization based on orthogonal test of 3P3R grinding robot
Zhang Dong, Yun Chao, Song Dezheng, Gao Zhihui
2010, 36(9): 1075-1079.
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The precision is impacted when the robotic grinding path is discontinuous and the gripper needs to be replaced during manufacturing. In order to solve this problem, a new type grinding robot, 3P3R, was proposed. Based on D-H notation, space kinematics modeling of the grinding robot was presented, and the kinematical equation was derived. A new robot frame including active work piece frame {W} and passive tool frame {T} was presented. It was pointed out that the relative position between the base frame of the robot {O} and {T} was a key factor which impacted on dexterous workspace of the grinding robot. The orthogonal test method indicated that the relative position in the direction of second joint of the robot was the most significant factor. Furthermore, the position of the contact wheel relative to the robot was optimized and the volume of the dexterous space was doubled. The dexterity of the robot was improved.
Channel assignment scheme for virtual hierarchical wireless mesh networks
Hu Zhiyuan, Su Jiayong, Guo Ji
2010, 36(9): 1080-1083.
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To gain high user diversity and routing stability in wireless mesh network, a virtual hierarchical structure was proposed, in which the nearby nodes were aggregated to virtual cells. Nodes inside the virtual cell can communicate with each other and take the identical traffic relay functions. The bottom-level virtual hierarchical architecture is formed by node-s direct connection inside each virtual cell, while the top-level virtual hierarchical architecture is consisted of virtual cells taking in routing functions. A generalized set T-coloring model, a kind of graph coloring model, was devised for the channel assignment algorithm of this virtual hierarchical architecture. Based on virtual cells, the radio frequency interference was introduced as the optimized indicator so as to reduce wireless channel interference and maximize the channel-s utilization while maintaining network connectivity. The cell splitting strategy was utilized to improve the network capacity and the fairness of the channel assignment scheme. The validity of the proposed scheme is proven by the simulation result.
Experience based grasping gesture synthesis and data glove calibration
Wang Bin, Dai Shuling
2010, 36(9): 1084-1088.
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An experience based gesture database construction method is proposed to solve the two primary problems for current calibration routine as: the difficulty for ground-truth data gathering and the oversimplified calibration model. By considering the anatomic structure of human hand and sensor layout of the data glove, the method established an accurate human hand kinematics model, which can realize flexible thumb movement and soft palm effect. Given the 3D object to grasp and the desired grasp task, an optimization procedure, combined with daily experience for grasping, was proposed for hand gesture synthesis. Least square regression and closed kinematics theory were used to find the accurate sensors’output transform parameters. The work described provides a novel method for ground-truth database construction. This approach has the advantages that it does not require any special outer device and can be implemented automatically, while still produce high fidelity performance.
Effect of humidity on storage reliability of plastic encapsulated microcircuits devices in hygrothermal environment
Liu Huicong, Xing Yang, Li Weiping, Zhu Liqun
2010, 36(9): 1089-1093.
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According to the storage reliability problems of plastic encapsulated microcircuits (PEM) devices in hygrothermal environment, effect of humidity on moisture absorption, surface estate and electrical performance of PEM was investigated through hygrothermal test. The results show that, humidity in the environment obviously affects moisture absorption process of PEM; Along with higher relative humidity at the same temperature, moisture absorption rate becomes bigger and moisture absorption content grows larger, but moisture has little effect on the time for moisture absorption content getting the biggest, moisture absorption content usually has the biggest value after 300h; Corrosion of component leads was found to be a main failure mode of PEM in hygrothermal environment, and the components have higher corrosion grade if the relative humidity is higher, and the defects, cracks and pinholes on the leads are considered to be the corrosion susceptible sites of the devices; In the tested storage time, humidity in the environment has little effect on the electrical performance of PEM.
Micro-Doppler analysis of spatial coning precession based on generalized S transform
Lei Peng, Wang Jun, Sun Jinping, Li Shaohong
2010, 36(9): 1094-1098.
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Precession characteristic is one of the significant properties for cone-shaped spatial target recognition. To analysis the micro-Doppler feature induced by precession, a method based on the generalized S transform was proposed. In the mathematical model of coning precession, the multi-coordinate system with the same origin was used to simplify model structure and computation complexity. Then the theoretical expression of the micro-Doppler due to precession was derived. The validity of the model was confirmed by computer simulation. Based on simulated radar data for precession cone, the generalized S transform was introduced and used to analyze the micro-Doppler feature in the condition of different signal to noise ratio (SNR). The experimental results in the joint time-frequency domain show that the method has large advantage in the time-frequency resolution, and is robust for the complicated micro-Doppler signal at low SNR.
Analysis of polarization dependence of fiber optic security systems
Li Chen, Zhang Chunxi, Liang Sheng, Li Qin
2010, 36(9): 1099-1102.
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The fiber-optic distributed disturbance sensor with dual Mach-Zehnder interferometers can be used in detecting intruder, cracks, and oil or fuel leaks. The position of the disturbance was obtained by the time delay difference between the output signals of the two Mach-Zehnder interferometers. According to the theory analysis, the records of the experiments in the major cases are compared. The polarization-induced fading phenomenon will lead to the inaccuracy of the position of the disturbance. The factors affected the system error are discussed. In order to find the relationship between the change of the environment conditions and the output states of polarization, the experiments were made. The experimental data and the simulation result on the Poincare sphere are similar.
Adaptive industrial CT outlier detection and accommodation using innovation orthogonal
Zuo Kai, Sun Tongjing, Li Zhenhua, Tao Liang
2010, 36(9): 1103-1107.
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The problem of defect recognition in industrial CT(computerized tomography) projection image was discussed based on the innovation orthogonality principle. Projection image was modeling in a 2-D state space structure. By analyzing the innovation orthogonality of Kalman filtering algorithm, a dynamic evaluation function and the corresponding threshold on the determination of image region and grey scale were defined respectively. A new adaptive defect recognition method was obtained. Based on 2-D Kalman filter, the proposed method was implemented for defecting image recognition adaptively which can improve the efficiency and accuracy for CT image recognition. An experiment was given to illustrate the effectiveness of the proposed method.
Dynamics and simulation of autonomous underwater vehicle based on control moment gyros
Lian Lun, Wu Zhong
2010, 36(9): 1108-1112.
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To improve autonomous underwater vehicle(AUV)-s low velocity control performance, a control moment gyro (CMG) was introduced as the attitude control system. Taking the fluid dynamics into account, the dynamic model of AUV was built based on CMG, and a simulation and analysis on AUV-s kinematics and attitude control also was made. The results show that AUV based on CMG has high efficient maneuverability and ideal low velocity control performance. Accordingly, AUV-s kinematics and attitude control can be realized. But the SGCMG steering law used doesn-t consider the singularity avoidance. Designing high performance steering law is the farther problem. It provides foundation for the design of steering law and attitude control.
Application of uniform design in missile components accelerated life testing
Wang Daozhen, Zhang Xiaojie, Shu Xiaofen
2010, 36(9): 1113-1116.
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Temperature and humidity are typical stresses that affect the life of missile storage. Accelerated life testing is becoming a new trend to predicate the reliability of missile storage.In order to optimize the experimental design and propose corresponding parameter estimation method, the testing sequence was adjusted according to the stress level of accelerated life testing which used the improved ‘uniform design-. Thus the completely fixed sample could be reused in the following experiment to reduce the test sample size.The mathematical model ‘stress-life- was derived under the double stress. Both maximum likelihood estimation (MLE) and robust regression were used for estimating the parameters instead of maximum likelihood estimation only because of which has a high request for initial value and often does not converge. The related example verified the correctness and applicability of the design of experiment and the parameter estimation method.
Radiation-shielding method of space electronic equipments and its software
Wang Gang, Wang Chunjie, Wang Bin
2010, 36(9): 1117-1120.
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A radiation-shielding method of space electronic equipments was researched, and its complicated calculating process was made into program by using computer aided design(CAD) technology and other developing software. The information from the files generated by the professional circuit board software Candence was extracted, and the circuit board models were created efficiently and automatically by using the secondary development function of the three-dimensional CAD technology. The dose point-s coordinates in the model were conveniently and automatically acquired and stored with the computer interactive technology. The background parameters were received from the software interface and the final report was created through the program automatically, by using the Visual Basic for application of the office software. Finally, the radiation shielding analysis software successfully functioned in the calculating of the cumulative space electronic particle dose value in different directions and positions, and in different structures and layouts of the space electronic equipments. Consequently, the reference and proof were provided for the electronic equipment structural anti-radiation design.
Image registration approach based on improved SIFT
Liu Jian, Zhang Guohua, Huang Linlin
2010, 36(9): 1121-1124.
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To resolve the problem of large angle and large scale image registration, an improved approach based on scale invariant feature transform (SIFT) is proposed. The log-polar technique was applied to estimate the parameters of rotations scales between reference image and sensed image. The images were segmented into sub-blocks and six candidates of sub-blocks were extracted according to information entropy, where SIFT features and moment features were fused to form a new feature descriptor. The image registration result was calculated from the matching points which were obtained by combining the Euclidean distance and the algorithm of iterative procrustes. The experimental results show that the proposed method is fast with high-precision.
Analytical method of electromagnetic susceptibility for radio frequency receiver at behavior level
Yu Xiaofeng, Yan Zhaowen, Xie Shuguo, Liu Yan
2010, 36(9): 1125-1130.
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Based on simplified Volterra model, an approach to the simulation analysis of electromagnetic susceptibility (EMS) for radio frequency (RF) receiver at behavior level was presented. Third order simplified Volterra model was adopted to analyze receiver EMS. A general criterion for EMS was proposed according to EMS response characteristics in frequency domain and then flow charts for calculating susceptibility thresholds by simulation were given. This approach is superior to the previous receiver EMS analysis which mainly relies on experiments but lack of simulation analysis. Take dual frequency GPS receiver interfered by continue wave as an example for in-band and out-of-band (including image frequency and intermodulation) susceptibility thresholds calculation. Simulation results show that the proposed method is not only valid and effective, but also reduces internal storage and simulation time which is suitable to RF receiver EMS analysis and practical in engineering and technology field.
Modeling and simulation of topographic effects for hyperspectral remote sensing
Wang Yachao, Zhao Huijie, Jia Guorui
2010, 36(9): 1131-1134.
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Aiming at geometric deformations and radiation changes caused by rugged terrain for the hyperspectral remote sensing images, a model of topographic effects for hyperspectral remote sensing was proposed. In the model, the imaging geometry relationship between simulation image pixel coordinates and ground space coordinates was established by using the sensor-s position, attitude and field of view. With the surface reflectivity, the digital elevation model(DEM) and the atmospheric radiation transfer model, the radiance image at sensor entrance slit in rugged terrain was calculated. After spatial resolution conversion the simulated remote sensing image was generated. Accurate modeling of topographic effects for hyperspectral remote sensing was achieved. Simulation was implemented to Hyperion data and other relevant data in Qulong, Tibetan. The simulation radiance image and the original radiance image show high consistent, which indicates that the fine simulation results are obtained by the proposed model.

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