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2010 Vol. 36, No. 12

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Flexible spacecraft attitude control based on perturbation method analysis
Cui Meiyu, Xu Shijie, Jia Yinghong
2010, 36(12): 1387-1391.
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In order to achieve flexible spacecraft high precision attitude control, using the perturbation method, the dynamic equations were divided into the zero order and first order systems. For the zero-order nonlinear time-invariant systems, taking into account the inertia uncertainty and disturbance, the nonlinear direct adaptive control law was improved, and the improvement of the gain adaptation law aimed at the higher precision. Also, the stability proof was given. For the first-order system, the proportional-integral(PI) controller and positive position feedback(PPF) controller were designed to suppression the vibration. The simulation shows that the perturbation analysis and the corresponding controller design can achieve the flexible spacecraft high precision attitude control.
Hard real-time multichannel scheduling design in avionics WDM networks
Zhou Li, Ding Fan, Xiong Huagang
2010, 36(12): 1392-1395.
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For avionics hard-time network, a composited wavelength division multiplexing (WDM) structure based on broadcasting network and wavelength routing network and scheduling structure model were proposed. For the hard real-time messages in the multichannel networks, a load ratio round-robin schedule method was proposed which allocating weight based on message load ratio in multichannel. Analysis of the differences between the interior messages and the exterior messages in the subsystem were given. Then the hard real-time schedulability conditions which the interior messages scheduled for one time and the interior messages scheduled for many times were derived to satisfy hard real-time communication of all of the messages in the avionics system. The key parameters were designed and optimized from the system resource usability and stability aspect for the real avionics system. Finally, a practice example was given.
Factors analysis of satellite images based on structure of clouds
Zheng Hong, Wu Xinghua, Cao Qiong, Li Wenqing
2010, 36(12): 1396-1399.
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To study the classification of satellite images availability, the description about the structural characteristics of clouds by coverage rate, thickness and fragment of clouds based on image information was proposed. The influence of these structural characteristics to satellite images availability was studied,and the orthogonal space of availability assessment was built. The characteristics of approximate linear and monotone between cloud structures and availability of satellite images were analyzed. The 500 satellite images categorized by people trained professionally were used to test the classifier. The result showed that 95% of the images classified by these three characteristics were the same as those classified by people trained professionally. The theoretical and technical support to build availability of satellite image evaluation model and automatically classifies satellite images according to the needs of users was provided by this description.
Sliding mode variable structure control of flutter suppression for two-dimensional wing
Song Chen, Wu Zhigang, Yang Chao
2010, 36(12): 1400-1403.
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Active flutter suppression (AFS), an attractive branch of aeroelasticity, and playing an important role of aircraft design was conducted on a two-dimensional wing which had a tailing-edge control surface. Sliding mode control (SMC) for AFS and its feasibility were investigated theoretically. The basic equations of motion were established by using quasi-steady aerodynamics forces. A sliding mode surface and a state feedback control for switching were designed in state space to achieve AFS. The principle of system stability provided by the SMC was discussed by state variables trajectory analysis. Further discussions about system robustness and time delay effects were also given. The results indicate that SMC strategy could be used for AFS and has potential usefulness in active aeroelastic control.
Application of constraint force equation method for missile launching dynamics modeling
Zhang Kenan, Chen Wanchun
2010, 36(12): 1404-1406,1426.
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A missile launching dynamics model based on the constraint force equation (CFE) method was presented, by applying the constraint equations and joint degrees of freedom in traditional launching dynamics equations. An incline launching missile system was researched, the missile body and the launching device were connected by a joint of two degrees of freedom, constraint forces and moments in launching process were obtained by calculating the dynamics model. In the end the same case was calculated using software automatic dynamic analysis of mechanical systems(ADAMS), results were compared and analyzed with the CFE method, a good agreement is achieved, so the application of this method used for missile launching dynamics modeling is verified and the method-s application range is extended.
Fault tolerance of parallel manipulator with actuation or structure redundancy
Yan Caixia, Zhan Qiang, Lu Zhen
2010, 36(12): 1407-1411.
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The fault tolerance approaches for actuator fault of parallel manipulator by using actuator redundancy were researched and the fault tolerance approaches with structure redundancy for the joint fault of parallel manipulator were discussed. According to the multiplicity of torque distribution in redundant actuated parallel manipulator, after partial actuator fault happens, the torque re-distribution among remaining working actuators was analyzed to realize fault tolerance. Considering the character of redundant structure parallel manipulator, the way to ensure the completion of task by aborting some structure freedoms was further studied. From kinematic and dynamic perspectives, the character and fault tolerance feasibility of the two types of redundant manipulators were presented. Taking 3-DOF planar parallel manipulator as an example, the kinematic and dynamic performance change of actuator and joint faulted manipulator was respectively stated. Furthermore, data simulating result indicates the feasibility of the fault tolerance with actuator and structure redundancy of parallel manipulator.
Real time scheduling algorithm based on rate-guaranteed in AFDX switch
Zhang Yongtao, Huang Zhen, Xiong Huagang
2010, 36(12): 1412-1416.
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Real time scheduling algorithm used in avionics full duplex switched Ethernet (AFDX) switches was studied, which is a key technique in AFDX. A priority real time scheduling algorithm based on rate-guaranteed(PRTRG) was proposed. Real time performance of PRTRG was analyzed using network calculus theory. Upper delay bounds with first in first out(FIFO) scheduling under a typical topology configuration were compared. The results confirm that PRTRG algorithm can effectively decrease the upper delay bounds of high priority data without losing the determinism of low priority data. At the same time, PRTRG algorithm prevents the congestion of one flow from spreading to another, and isolates the flow in the switch.
Design theory of thrust vector control servo mechanism for a type of spacecraft
Lu Hao, Li Yunhua, Zhu Chenglin
2010, 36(12): 1417-1421.
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Addressing the requirements of servo mechanism applied in a certain type of spacecraft, one servo mechanism for thrust vector control was designed. By comparing hydraulic servo mechanism,pneumatic servo mechanism and electric servo mechanism, their characteristics were obtained and the electric servo mechanism was selected. The key techniques of electric servo mechanism were researched, including the design of electromechanical actuators, drive and control technology and redundancy technology. The two-degree of freedom dynamics model of electric servo mechanism with two redundancies was established and its dynamic characteristics were simulated. Theory analysis and simulation results show that the scheme of electric servo mechanism is practical and logical. The electric servo mechanism not only meets the basic demands of the spacecraft, such as high reliability and good maintainability, but also satisfies the requirements of dynamic performance targets for controlling system.
Method of scale extension in distributed virtual environment under CS structure
Zhang Jiong, Lei Xiaoyong, Dai Shuling
2010, 36(12): 1422-1426.
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According to the client server(CS) architecture in distributed virtual environment(DVE), it extended the problem of scale extension into the optimization of node partition between multi-node and multi-server. An evaluation equation of the node partition was also proposed. Based on the characteristics of DVE application, the whole process was divided into two steps,predisposition and runtime regulation. The process of predisposition was achieved partition rapidly and efficiently with density primary strategies and greedy randomized adaptive search procedures(GRASP), and the evaluation equation was used to adjust partition result. In real-time regulation process, the condition of node partition was restricted strictly to achieve real time distribution. Compared with the traditional methods, this method has better solved the contradiction between the real-time quality and the maturity of distribution, and has been proved to be of great practical value. The experimental results illustrate the effectiveness of this method and a conclusion was drawn.
Effect of cyclic hygrothermal environment on interfacial property of CCF300/BMI composites
Feng Tongbo, Zhao Yan, Luo Yunfeng, Zhang Zuoguang
2010, 36(12): 1427-1431.
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An experimental investigation was conducted in order to study the effect of cyclic hygrothermal environment on the interfacial property of CCF300/5428 composites. The moisture weight and interlaminar shear strength(ILSS) of CCF300/5428 specimens of each stage during three absorption-desorption cyclical processes were tested. The morphology of interface between carbon fiber and resin was characterised by applying scanning electron microscope(SEM) method. The results show that the composites exhibit higher diffusivity after suffering reabsorption steps. The reversible effects of water on ILSS of the composites can be eliminated after desorption. The ILSS of the composites degrade obviously due to high temperature, while the humidity has weak effect on the mechanical performance of the composites at room temperature.
Distributed cooperative guidance for multiple heterogeneous networked missiles
Zou Li, Ding Quanxin, Zhou Rui
2010, 36(12): 1432-1435.
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A distributed leader-follower heterogeneous multi-missiles cooperative guidance law was proposed based on local nearest-neighbor communication. The distributed local communication topology between the missiles was modeled using the graph-theoretic methods. The relations between the communication topology and the performance of cooperative guidance system for multiple heterogeneous networked missiles were investigated. Only the measurable states of missiles were required to be communicated between the nearest-neighbor missiles for the proposed distributed heterogeneous multi-missiles cooperative guidance law, which resulted in the characteristics of scalability and little communications. As an example, the distributed leader-follower missile cooperative guidance law for one leader and four followers was designed. The simulation results demonstrated the effectiveness of the proposed distributed cooperative guidance law.
Airflow thermal simulation and comfort evaluation of commercial airliner
Wang Lijing, Wang Zhaoxin, He Xueli
2010, 36(12): 1436-1439,1452.
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Air velocity field and temperature field of cockpit will affect the pilots- thermal comfort and performance directly, which are important parts need to be considered in the design of cockpit structure and environmental control system. After full-size three-dimensional model of B737-800 cockpit being established, a commercial computational fluid dynamics(CFD) software Fluent was used to calculate the flow field and temperature field of cockpit in high-altitude night work. Then the average temperature evaluation and the predicted mean vote(PMV)on the thermal sensation scale were used to evaluate cockpit temperature environment. A questionnaire was given to the pilot to obtain cockpit air flow and temperature comfort subjective evaluation. The results of simulation and subjective evaluation both indicate the B737-800 cockpit is a comfortable environment at night at high altitude. Besides, the trunk and legs feel a little uncomfortable as a result of slight coolness. The agreement of simulation results and evaluation results validates the accuracy of the cockpit airflow thermal simulation.
Schottky diodes mixing performance evaluation in terahertz band
Fan Guoli, Jiang Yuesong
2010, 36(12): 1440-1443.
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Schottky diodes mixing performance can decrease as high-frequency effects in terahertz band. The finite difference technique was used to calculate the electromagnetic field within the diode chip and the influence of high-frequency effects on mixing performance was analyzed from the shunting of the junction capacitance, the skin effect, the plasma resonance effect and velocity saturation effect, respectively. Finally, the structure parameters were optimized when the cut-off frequency as the figure of merit. Simulation results show that diode mixing performance can be improved by reducing the anode diameter and the epilayer thickness, and increasing the epilayer doping density, and will benefit the development of the high frequency mixing diodes.
Structure parameters field calibration of fly point scanning shape measurement system
Li Xudong, Cui Lei, Jiang Hongzhi, Zhao Huijie
2010, 36(12): 1444-1447.
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The calibration of structure parameters of a triangulation-based fly point scanning shape measurement system is usually a non-linear problem. A practical and easy-to-use calibration procedure of such system was proposed and implemented. The proposed calibration procedure was based on the coordinate transformation between the feature points and their images taken by the measurement system. Several pictures of a special designed planar calibration board were taken from arbitrary orientations. There was no need to precisely measure the position and altitude of the calibration board. A planar board surface and a cylinder surface with known diameter were measured by using the obtained structure parameters. The average error of the distances between measuring points and the fitted plane or cylinder was used to evaluate the calibration accuracy. The proposed calibration procedure can meet the needs of the calibration such as validity and stabilization. It can also be used for the calibration of other triangulation based shape measurement systems.
On-line compensation technique for micromechanical gyroscope random error
Yuan Gannan, Liang Haibo, He Kunpeng, Xie Yanjun
2010, 36(12): 1448-1452.
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To improve the measurement precision of micro electro mechanical system (MEMS) gyroscope, an on-line compensation approach for MEMS gyroscope random error was presented. The autoregressive moving average (ARMA) model of random error was established under static condition, and the fictitious noise compensation technique was introduced to accommodate the time-varying model. Due to the unknown movement of carrier, the technique of maneuvering target tracking was presented to obtain the maneuvering angular rate model. The random error and angular rate were estimated in real-time by using adaptive Kalman filter in the dynamic test. The result of test indicates that the model of random error, the angular rate, and the algorithm of filtering can satisfy the dynamic application of the MEMS-based attitude heading reference system. Furthermore, the precision of system is greatly improved after compensated.
Variable structure control for variable pump controlling variable motor
Wang Yan
2010, 36(12): 1453-1456.
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Variable structure control for variable pump controlling variable motor (VPCVM) systems based on feedback linearization was presented to overcome the defects, such as huge overflow losses, slow speed regulating and poor full capacity utilization, arisen from the conventional independent control of variable pump or variable motor in the systems. The mathematical model of VPCVM was established, and the multiplicative nonlinear property existing in the system caused trouble for the motor speed controlling. To improve the VPCVM performance, the VPCVM nonlinear model was transformed into a linear system by feedback linearization. For the closed hydraulic speed controlling system with double-variable, the variable pump displacement can be deduced from motor expected speed and variable motor displacement. The variable structure controller was designed to control variable motor speed and its stability was proved according to Lyapunov theory. Simulations show that our approach has the capacity for speeding up system response and reducing overshoot of VPCVM system, and features with robust performance.
Endmember extraction method based on morphology and orthogonal subspace projection
Li Na, Zhao Huijie
2010, 36(12): 1457-1460.
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An automatic endmember extraction method based on the extended morphology and the orthogonal subspace projection was proposed to solve the problems, including identification of different endmembers with similar spectra and the endmembers extraction used by the spectral or spatial information only. Extended dilation and erosion operators were used to calculate the morphological eccentricity index (MEI), and the MEI was used to extract the endmember set. Spectral angle matching (SAM) was applied to distinguish different endmembers, and then the endmember was projected to its orthogonal subspace to eliminate the effect of endmembers that had been extracted. The airborne hyperspectral data was used to evaluate the performance of this method. The results illuminate that image endmembers are extracted automatically without any prior information and endmembers with similar spectra are distinguished effectively.
New 3-D separation structure in juncture flows
Wang Xuee, Zhang Hua, Wang Hong, Fu Liqun
2010, 36(12): 1461-1464,1479.
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A computational and particle image velocimetry(PIV) experimental study of three dimensional steady separation structure generated in juncture laminar flows was presented. It confirms the existence of outmost attachment saddle point structure of horseshoe vortex in juncture flows. The outmost streamline doesn’t rise from the plate but attaches to the plate by passing through a space singular point. There also exists an evolvement rule of horseshoe vortex structure from outmost attachment saddle point structure to outmost separation saddle point structure. The evolvement is influenced by the blunt extent of the model, the boundary layer thickness and the Reynolds number. Under curtain boundary layer and the Reynolds number conditions, the horseshoe vortex will change from outmost separation saddle point structure to outmost attachment saddle point structure as the blunt extent of the model becomes smaller. For a same model, the horseshoe vortex will tend to be outmost separation saddle point structure as the boundary layer thickness and the Reynolds number increases, contrarily it will tend to be outmost separation saddle point structure.
Ground target tracking method research based on adaptive estimation for electro-optical platform
Zhang Jing, Wang Honglun, Gai Wendong
2010, 36(12): 1465-1468.
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A harmful effect on stability and tracking accuracy of the system was produced by the time-delay of tracker in an image-based target tracking system. Analyzing the ideal control command of the electro-optical platform servo system, a delay compensation method based on adaptive estimation was proposed. This method used target position and unmanned aerial vehicle position and attitude to predict the control signals of the electro-optical platform. The target velocity was estimated by an adaptive estimation rapidly. The results of simulation show that the tracking accuracy of the electro-optic platform as the target maneuvers and the unmanned aerial vehicle maneuvers can be improved effectively.
Efficiency analysis and thermal-hydraulic modeling of aerial piston pump at whole work condition
Li Yonglin, Xu Haojun, Cao Keqiang, Hu Liangmou
2010, 36(12): 1469-1472.
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Thermal-hydraulic model of aerial piston pump was established based on analysis of power loss and heat transfer. Power loss model of pump was obtained, considering the influence of load pressure, input rotational speed, swash plate angel and oil viscosity. With the analysis of heat transfer in pump, the thermal-hydraulic model of pump was established to display the temperature change in all parts of the pump, which takes advantage of formula of temperature change in control volume. A hydraulic system, consisting of piston pump was simulated with Dymola to show efficiency and power loss of pump at different input rotational speed and load pressure. Temperature rising in different parts of pump at different input rotational speed and supply flow was analyzed.The result shows that the input rotational speed and load pressure impact the efficiency and power loss of pump, and temperature rising in pump presents differently in characteristics at different input rotational speed and supply flow.
Object-FMA based software code inspection approach
Huang Baiqiao, Zhang Hong, Lu Minyan, Li Zhen
2010, 36(12): 1473-1479.
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There are two disadvantages in the checklist used in traditional code inspection: there is no mapping mode from code to the defect record of checklist, and the defect modes in the checklist is incomplete which may result in omitting the code defects in code inspection. To resolve the above two problems, a new code inspection approach was presented by dividing the code into different levels and using failure modes analysis at different levers instead of the traditional checklist. Furthermore, an object failure modes analysis method (Object-FMA) was proposed to systematically analyze the failure modes of code objects and establish the failure modes database for code object in different levels. Finally, this Object-FMA approach was applied into the code inspection of military software. The results show that the proposed approach can provide a mapping mode from the code objects to the failure modes database, and improve the efficiency of the code inspection. The results also show that this Object-FMA approach can not only find the defects in the code lexical, syntax or semantic which can also be detected by traditional checklist, but also effectively find the defects caused by the negligence of developer or the algorithm error which may can-t be detected by traditional checklist.
Molding surface design of membranous disc couplings based on fatigue life analysis
Li Lin, Fan Yu
2010, 36(12): 1480-1484.
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A membranous disc coupling design method was proposed based on the standpoint of fatigue life analysis, to select and evaluate the molding surface function at a given operating condition. The method of modeling membranous disc in finite element method(FEM) was discussed, and the boundary conditions were derived based on this FEM model. A dynamic analysis method was presented to get the stress caused by complex operating condition. Based on dynamic stress analysis, effects on fatigue life caused by several typical complex operating conditions were given. Fatigue life of three typical membranous disc couplings with different molding surface were compared, and the method of evaluate the design of molding surface of membranous disc coupling by fatigue life analysis was suggested. The corresponding operating conditions of the typical molding surfaces were given.
RMS research based on three dimension model of support system with simulation method for military aircraft
Li Jinzhuo, Wang Naichao, Ma Lin
2010, 36(12): 1485-1489.
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The issue of how to obtain reasonable reliability, maintainability and supportability (RMS) design parameters in the development of military aircraft was researched.The framework of RMS design parameters simulation model was constructed via the three-dimensional model of support system and the rule of modular design principle. The framework contains four modules includinag mission module, function model, operations and maintenance model, support organization module and which are the kernel of the framework. The relationship and the content of data streams between these modular were expatiated. According to the definition of evaluation parameters, the method of how to calculate them using simulation data was given. To verify the feasibility and validity of the simulation framework, the Monte Carlo simulation is used in the trade-off RMS design parameters and a family of design values fulfilling the constraints of support effectiveness requirements is obtained.
Novel approach to video object detection and precise segmentation
Zhao Wenzhe, Qin Shiyin
2010, 36(12): 1490-1494.
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Taking into account multiple objects detection in dynamic video scene, a method based on variational optimization of optical flow and mean shift was proposed. A variational optimization model for optical flow field was built according to constraints of multiple objects detection in dynamic video scene. The proper numerical solution was then given by this kind of optimizing calculus of variation. With the optical flow optimized solution, a high precise segmentation method was proposed. This approach can be used in the situations of both motion camera and stationary one. Meanwhile it can also be used to detect several targets in dynamic scenes simultaneously without learning in advance and manual intervention so as to be implemented automatically. A lot of experiment results validate the effectiveness of the proposed method.

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