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2008 Vol. 34, No. 04

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Optimal method of human-machine coupling with preview information
Wang Liang, Lu Yongjin
2008, 34(04): 361-364.
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For fully automatic machine system is awkward to deal with open and complex task, human quantitative and qualitative intelligence itself tends to be synthesized with it in such case then human machine system is constructed which is different from simple human-machine system in information interface channel. Based on conception of human-machine integrated system, an optimization method of human-machine coupling with preview information in operation signals channel was discussed. The significance is that the dynamic relationship of human, controlled machine and environmental information was studied, and an operable theoretical method for optical human-machine coupling was proposed. This method utilizes finite preview information as internal status of the system to expand it. Simulation shows the compensatory effect of preview steps on human delay and the relationship between preview steps and leading indication.
Pressurized pressure-restoring system for large scale vacuum chamber
Chen Jinming, Yuan Xiugan, Huang Bencheng
2008, 34(04): 365-368.
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Pressure-restoring process has strict requirements in some special purpose establishments such as ground simulator for astronauts- training. A pressurized pressure-restoring system was designed for large-scale vacuum chambers with a view of analyzing the pressure-restoring process with high speed requirement. Simulation models were established with special focus on heat transfer, while incorporating segmented centralized parameter models of a long gas tube. An simulation analysis was done to the models. The calculations show that the pressurized pressure-restoring rate is much greater than that of regular pressure-restoring, the rate is strained by heat transfer, and the segmented centralized parameter models of the long gas tube deliver better accuracy than the other kinds of models but with no more calculating jobs. Compared the simulation calculations of heat transfer with the actual debugging situation in the pressure-restoring test of a large 200m3 chamber, the error is no more than 5%, which proves the reliability of the whole simulation.
Modeling and control of vertically launching parallel vehicle
Yin Yongxin, Yang Ming, Wang Zicai
2008, 34(04): 369-372.
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In order to effectively control the motion of vertically launching parallel vehicle, an attitude control method for vertically launching parallel vehicle was presented. A singularity of Euler kinematical equations was analyzed, and kinematical equations of attitude motion were given based on quaternion method. An attitude dynamical model of vertically launching parallel vehicle was constituted. Mathematical models of thrust vector control were presented for vertically launching parallel vehicle. Based on these mathematical models, control efficiencies were contrasted for different thrust vector control. And with a view to convergence of quaternion, switching functions of attitude control system were given. With a view of robust stability for conditioned uncertainty, an attitude control law was designed using sliding mode control theory. Simulation results show that this method can implement efficiently attitude control for vertically launching parallel vehicle.
Influence of pixels to graphical electromagnetic computing accuracy and its solution methods
Fang Xiang, Su Donglin, Liu Yan
2008, 34(04): 373-376.
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In graphical electromagnetic computing (GRECO), the image rendering resolution was adjusted to improve the physical optics (PO) integral evaluation accuracy. In the PO integral calculation, the visible scattering surface was approximated by flat panels at the pixel level. Therefore the PO integral was evaluated numerically by using a GRECO formula which is equal to the coherent addition of the contribution from all the pixels in the target image. The electrical size of screen cell per pixel was bounded with a maximum Nyquist spatial sampling interval, thus a GRECO image resolution determination criteria which meets the precision requirement of high-frequency RCS calculation was suggested, followed by an image resolution adjusting implementation. Illustrative numerical results for a canonical and a complex targets were presented, which demonstrate the validity of the GRECO image resolution determination criteria.
Integrated heading system based on differential magnetic compasses
Hao Zhenhai, Huang Shengguo
2008, 34(04): 377-380.
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To solve the magnetic compass interference problem caused by the dynamic interference magnetic field in urban traffic environment, the feature of the dynamic magnetic interference was analyzed. And the concept of the differential magnetic compasses(DMC) was proposed. An integrated heading system module based on the DMC and the rate gyroscope was designed. The dynamic interference recognition technology of DMC based on the judgment of the threshold value was investigated. The agreement of the theoretical analysis with the real navigation experimental results shows that the DMC can recognize the dynamic magnetic interferences better, compared with single compass. The application range of the magnetic compass in the urban traffic environment is extended. The robust and the precision of the integrated heading system are also improved.
Dynamics analysis of lunar lander-s landing process
Wang Chuang, Liu Rongqiang, Deng Zongquan, Gao Haibo
2008, 34(04): 381-385.
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The prototype of spatial trussed lunar lander was taken as a researching object. It was designed and manufactured by RCAMC HIT(Research Center of Aerospace Mechanism and Control, Harbin Institute of Technology). The simplified model of the lunar lander construction was given. Then, the location coordinate equations of every lunar lander foot and center of mass in inertial coordinate system were deduced. Based on these location coordinate equations, the lunar-s quasi-static stability condition was gotten. By analyzing the lunar lander-s transient dynamics behavior during the landing time, the formulas to calculate the transient dynamic parameters of the lunar lander during the landing time were derived; Through scattering time variables, the calculating procedures that can be imitated dynamic characters of the whole landing process were put forward, which laid a foundation for further research on the lunar lander-s landing dynamics behavior.
Durability analysis technology and application when loading spectrum is altered
Dong Yanmin, Liu Wenting
2008, 34(04): 386-390.
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In order to satisfy the requirements on durability evaluation of aircraft structure full scale fatigue (durability) testing when loading spectrum is altered, based on probability fracture mechanics approach and improved crack initiation approach of durability analysis, a method was presented to establish equivalent initial flaw size distributing that describes structural detail initial fatigue quality using all durability testing date under different load spectrums, and an accumulated damage method was presented to calculate crack exceeded probability in every stress district when loading spectrum is altered. Then a durability evaluation approach that can exactly predict structure economy life when loading spectrum is altered was presented. It has a great value and has been successfully applied for the durability evaluation of some aircraft structure full scale fatigue testing when loading spectrum is altered.
Design of the workflow form system based on shared model
Tang Wenzhong, Mo Weidong
2008, 34(04): 391-395.
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Form is the information carrier in the application system. The process of form system, workflow system and the coupling pattern of the workflow engine and form in the traditional workflow form system were analyzed. The definition of the form model and workflow model was deeply studied based on the modeling method, and they were combined in the process of modeling. The mechanism of dividing the workflow form by fields and sharing the same form in the same workflow model was exploited at the same time, and also a developing method of workflow form system based on shared model was presented. This method adopts form engine and workflow engine technology to separate form data and process of workflow data and make workflow engine deal with form data according to the combination of form model and process model. The detailed introduction of the process and characteristics of the method was also given.
QoS analysis on IEEE- 1394b fiber optical bus system
Duan Jingyuan, Zhang Chunxi, Shi Jieqin
2008, 34(04): 396-399.
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In order to solve the problem of network delay and information obstacle in avionics system, the key characteristics which are bandwidth reservation mechanism and average response time of IEEE-1394b fiber optical bus system used in avionics system were analyzed. The equation which the QoS (quality of service)of isochronous data transfer and asynchronous data transfer must satisfy was derived (hard QoS) on the ground of bandwidth reservation mechanism in IEEE-1394b protocol. Considering the mixture of isochronous and asynchronous requests in admission control for QoS service, the QoS of asynchronous requests was analyzed based on queuing theory (soft QoS). For the case of ignoring reply interval, the average response time of IEEE-1394b asynchronous requests queues was got. The QoS service of IEEE-1394b was evaluated in IEEE-1394b fiber optical bus experimental system in the end. The theoretic derived results were verified. It has a directive meaning in QoS design of IEEE-1394b driver layer.
Expanded stochastic DAG model
Hu Kai, Jiang Yan, Chen Shiran, Xiang Yunting
2008, 34(04): 400-403.
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Considering the fact that parallel program structure can induce the randomcity of tasks- computing and communication cost, the definition of stochastic directed acyclic graph(DAG) was expanded, in which the heterogeneity and the parallel program structure were considered together. Based on this model, the method to computing the nodes- earliest start time(EST) and standard deviation were presented, which was expressed as the expectation operator of a summation of standard deviation and the mean. A parallel program modeling method was provided based on the expanded stochastic DAG. The expanded definition has been validated by experiments. The results show that by optimizing the parallel program structure and considering the heterogeneous environment, the parallel program execution efficiency can be improved greatly, as well as the load-balance.
Effect of temperature shock on transmission properties of frequency selective surfaces
Zhang Chaofa, Li Huanxi, Lü Mingyun
2008, 34(04): 404-407.
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Temperature shock test followed the criterion of GJB 150-86 was completed for frequency selective surfaces (FSS) of different coatings and different machining process. The stability of transmission properties of FSS under temperature shock test was studied by the difference before and after the test on resonant frequency, transmission loss, band width and sensitivities to the varying angles of incidence of FSS. The results are shown as follows. It has great influence of temperature shock test on the transmission properties of FSS, which mainly displays in two sides, transmission loss and band width. After the temperature shock test, transmission loss of FSS increases by 50%~300% for different coating and machining process FSS and the increase extent becomes greater with the increase of the incidence angle. The band width increases by 50%~70% for different FSS. The temperature shock has little effect on the resonant frequency and sensitivities to the varying angles of incidence and it has different influence for different FSS. In contrast with simple cell FSS, the transmission properties of compound cell FSS have more obviously change after temperature shock.
Five-axis electro-hydraulic simulator dual motors synchronizing control
Wang Yanshan, Li Yunhua, Wang Yiqun
2008, 34(04): 408-411.
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A low cost approach for dual hydraulic motors synchronization was presented, which was used in five-axis flight motion electro-hydraulic simulator. The controller contained main immune controller and synchronizing controller. The main immune controller, which used the displacement, velocity, pressure state of the master motor with immune algorithm fuzzy adaptability and robustness, was designed to satisfy the static and dynamic performance of the master motor. Its output was given to servo amplifiers of two motors. For synchronization drive control of dual motors, the synchronizing controller was designed by simply taking signals of two motors- pressure sensors and feed-forward them to the slave motor- servo amplifier, aiming at eliminating the pressure difference of two motors. Compared with taking two encoders to measure angle displacement difference or two tachometers to measure velocity difference, the proposed method is of low cost and easy for engineering. Simulation results show that it can achieve high synchronization accuracy even when parameters of the simulator are changed greatly.
High speed polishing CVD diamonds with hot metal plate
Ma Yongtao, Sun Yujing, Chen Wuyi
2008, 34(04): 412-416.
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By using high speed polishing equipment based on hot metal plate method(HMPM), experiments were carried out on temperature, speed, load and time to polish CVD(chemical vapor deposition) diamonds. Optical balance was used to compare the diamond weight before and after polishing. Tool microscope and atomic force microscope(AFM) were adopted to research the polished surface. The research shows that high polishing speed is helpful to the surface quality and polishing rate. Under the following conditions: temperature 850℃, polishing speed 164mm/s, load 24.892N, polishing time 120 minutes, the degree of roughness on the diamond can reach to R a 0.016μm compared to the original roughness of R a 9.67μm. Surface topography taken by AFM shows that there are only a small amount of summits which are 60~70nm in height and the shapes of summits are in special character. The height of high summits is 2 to 3 times than that of ordinary summits. The special topography should be related with the direct pressure polishing method.
Numerical simulation of airfoil transonic viscous flow using GAO-YONG turbulence model
Yan Wenhui, Yan Wei, Gao Ge
2008, 34(04): 417-421.
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Numerical simulation of transonic viscous flow around NACA0012 airfoil and RAE2822 airfoil based on Gao-Yong compressible turbulence model were presented. The convection term and the diffusion term were discretized by the third-order ROE scheme and the second-order center difference(CD) scheme respectively. The Runge-Kutta time marching method was applied to solve the space discrete control equations. The calculations accurately predict distribution of pressure coefficient on the airfoil surface, location of shock wave and distribution of contour of the Mach number. Shock-wave/boundary layer interaction and translation from the laminar flow to the turbulence flow on the airfoil surface were analyzed. The numerical results agree with the experimental data very well. The results demonstrate that Gao-Yong compressible turbulence model has a powerful capability to accurately simulate transonic viscous flow around the airfoil. A method for forecasting location of translation based on theory of orthotropic turbulence viscosity in the Gao-Yong compressible turbulence model was presented.
Information fusion technology in FOG/GPS integrated navigation system
Zhang Xiaoyue, Zhang Chunxi
2008, 34(04): 422-425.
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Fiber optic gyro(FOG) strapdown inertial navigation system used in orientation has an advantage of independence, but its system error accumulates with time; Global position system(GPS) can provide more accurate information, but it is interfered easily. FOG and GPS was integrated using information fusion technology. GPS height information was introduced into vertical channel to restrain error increasing basing on setting feedback coefficients. GPS latitude, longitude and horizontal velocity was introduced as Kalman filter observation to remove accumulating error. Information fusion means presented here was applied in a medium-precision FOG/GPS navigation system, and tested in a vehicle. Error of system output positioning parameters was not increased along with time. The testing results are presented to validate the availability and engineering utility of the information fusion means.
Effect of friction on identification of materials properties from spherical indentation
Qian Xiuqing, Zhang Jianyu, Fei Binjun
2008, 34(04): 426-430.
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By using the dimensional analysis and finite element computations, the frictional effects on spherical indentation of strain hardening solids to exact the plastic properties of material are examined. By defining a representative strain dependent on the energy, based on the representative strains and representative stresses corresponding to two different indentation depth, the plastic properties of materials are uniquely determined. Then the frictional effects on the indentation response, representative stress and identification of the mechanical properties can be obtained. It is shown that the effect of friction on the indentation is closely related to the strain hardening exponent, the ratio of the elastic modulus to yield stress and the ratio of the reversible work to the total work done by the indenter. The bigger the ratio of the reversible work to the total work is, the smaller the effect of friction is. The effect of friction on extracting the mechanical properties cannot be ignored. While the friction coefficient is unknown, for the materials with the bigger ratio of the reversible work to the total work, the reasonable result can be obtained using the coefficient taken as 0.15 to extract mechanical properties.
304 stainless steel rotary-twin-focus laser-TIG hybrid welding
Li Xiaohui, Wang Su, Xia Caiyun
2008, 34(04): 431-434.
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In order to improve the laser-arc hybrid welding quality, the rotary-twin-focus laser-TIG(tungsten inert gas) hybrid welding was put forward, which is a new welding method that can improve the welding efficiency at the same time. With the rotary-twin-focus laser-TIG hybrid welding head designed by Beijing University of Aeronautics and Astronautics, a detailed experiment of rotary-twin-focus laser-TIG hybrid welding with different welding parameters was carried out on the 304 stainless steel plate, and the weld parameters infection for the weld appearance quality was analyzed concretely. The results indicate that the coupling effect of laser power and the welding current intensity are the main factors for efficient synergetic effect in rotary-twin-focus laser-TIG hybrid welding process; however the rotary-twin-focus laser rotary frequency has unapparent effect on the weld width and penetration. Compared with the laser welding and the TIG welding process, rotary-twin-focus laser-TIG hybrid welding with the rotary-twin-focus laser and arc efficient synergetic effect increases the welding heat sources efficiency effectively.
Design and implementation of multi-rate quasi-cyclic low-density parity-check code decoder
Zhao Ling, Zhang Xiaolin, Zhi Gang
2008, 34(04): 435-438.
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To meet the requirement of using multi-rate low density parity check(LDPC) codes in the communication system, a 7Kbit code length multi-rate LDPC codes decoder architecture was presented and implemented on a Altera field-programmable gate array device. The similarity between different check matrixes of different rate was analyzed and the variable node processing unit (VNU), the check node processing unit (CNU) and the iteration storage location duplication in the decoder were explained. By adding several switches in the input ports of the VNUs and the CNUs, these processing units can work under different code rates. Using pin selection, three operating modes, namely, the irregular 0.4 code mode, the irregular 0.6 code mode and the irregular 0.8 code mode, are supported. The synthesis result indicates that the proposed multi-rate LDPC code decoder using just a little more resources than a single 0.8 rate LDPC code decoder without any performance loss.
Calibration-compensation method for micro inertial measurement unit based on MEMS
Sun Hongwei, Fang Jiancheng, Sheng Wei
2008, 34(04): 439-442.
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According to angular velocity and accelerate error mathematical models of micro inertial measure unit (MIMU), a kind of quick calibration-compensation method called dynamic overturn 6 positions was proposed based on special features of micro electronic mechanical system (MEMS) inertial devices, which only needed one single axis velocity rolling plate (without referring to the north). Comparing with traditional calibration-compensation method, this method was simple, convenient and could identify forty-five error coefficients of MIMU. The precision of error coefficients identified was high, and this method was especially fit for low precision strapdown inertial measure unit. Through theoretical analyses, calculations and experiments, the result shows that this calibration-compensation method could improve the MIMU accuracy by 2~3 magnitudes.
Numerical simulation on flow control of stalled NACA0015 airfoil with synthetic jet actuator in recirculation region
Zhang Panfeng, Wang Jinjun
2008, 34(04): 443-446.
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Numerical simulation on the separation flow control of stalled NACA0015 airfoil at high angle of attack (20°) was carried out with synthetic jet actuator in the recirculation region. The Reynolds averaged Navier-Stocks equations were solved by commercial computational fluid dynamic software package Fluent6.1. The mechanism of flow separation control with the synthetic jet actuator in the recirculation region was also discussed by analyzing the vortex structure separated from the airfoil and the flow field near the actuator orifice. When the synthetic jet actuator is in the recirculation region of the airfoil, the separation point on the suction side of the airfoil can be delayed and the recirculation region can be decreased, which result in the lift enhancement of the airfoil. When the jet orientation is perpendicular to the airfoil wall with the normalized actuator frequency and the jet velocity ratio setting as 1, the lift of the airfoil is increased by about 40%.
Fast calculation of wide angle RCS pattern of objects based on interpolation technique and FDTD method
Sun Weiping, Wu Zeyan
2008, 34(04): 447-451.
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Fast calculation of wide angle radar cross section(RCS) pattern of 3-D objects based on multinomial interpolation approximation and spline approximation was presented. When interpolation technique was introduced in finite difference time domain(FDTD) method, the calculation time was reduced. Firstly, several angles of incidence were chose in whole range of angle, and FDTD calculation were employed with those angles one by one, and the tangent electric and magnetic values on extrapolation boundary were obtained. Then, the approximating functions related to angle of incidence were gained. Secondly, the tangent electric and magnetic values on extrapolation boundary were calculated by approximating function in whole range of incident angle. Finally, wide angle RCS pattern of 3-D object were calculated by a near-to-far field transformation. The numerical results are in good agreement with the results achieved by the method of FDTD at any incident angle, even if several interpolation node is used, and the computational time is reduced.
Data integration of design, analysis and manufacture for aircraft composite structures
Zhang Lihua, Fan Yuqing
2008, 34(04): 452-455.
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Implementing digital composite structure definition is the base of achieving the data integration of design, analysis and manufacture for aircraft composite structures. The digital composite structure definition consists of the modeling of geometry and the modeling of material structure. The process of material structure modeling and data contents of laminate lay-up definition were summarized. The fact that today the composite structures can not be analyzed based on the final shape with true fiber orientations was put forward. True fiber orientations of discrete triangle elements were used to approximate the final state of ply fibers and XML(extensive markup language) file was used to describe laminate lay-up definition data. Using automatic mapping of fiber orientation data to the finite element mesh to obtain the automatic data transfer from design to analysis was discussed. At last, the data integration of design with cutting system and laser projection system and the organization of interface data were studied.
Flight loads analysis of a twin-tailboom aircraft
Xiao Zhipeng, Wan Zhiqiang, Liang Meng, Yang Chao
2008, 34(04): 456-459.
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Flight loads and aerodynamic derivative analysis of a twin-tailboom aircraft was performed. The longitudinal aerodynamic derivative, the efficiency of each control surface and the load distribution were considered emphatically, as a function of the tailboom stiffness of longitudinal bend and the flight dynamic pressure. The tailboom stiffness of longitudinal bend has quite an effect on the longitudinal static stability, the efficiency and anti-efficiency speed of the elevator on the horizontal tail, even the load distribution of the horizontal tail. The stiffness of the tail section, especially the tailboom stiffness of longitudinal bend, uasually causes the weakness, as the aeroelastic analysis is processing on a twin-tailboom aircraft. The design standard of the tailboom stiffness must be controlled strictly.
Effect of spaces between cars on aerodynamic characteristics of cars in overtaking process
Zheng Hao, Kang Ning, Lan Tian
2008, 34(04): 460-464.
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Numerical simulation of unsteady flow fields around overtaking and overtaken cars by two different overtaking spaces between cars were conducted with computational fluid dynamics(CFD) method. Spalart-Allmaras turbulence model, QUICK discrete scheme, SIMPLEC pressure and velocity coupling arithmetic and unstructured tetrahedral mesh and dynamic mesh technology were adopted. Both car models were simplified fastback reduced scale car models. The side forces, rolling moments and yawing moments of the cars during the overtaking process were calculated. The influences of the flow field on the aerodynamic forces were analyzed according to the distribution of velocity and pressure fields. The results show that the variation tendencies of the side force, rolling moment and yawing moment of the overtaken car by two different spaces are the same. But the variation tendencies of these forces are different from each other; The variation tendencies of the side force, rolling moment and yawing moment of the overtaking cars by two spaces are different apparently.
Aerodynamic noise of a fastback car in uniform and accelerated motion
Lan Tian, Kang Ning, Zheng Hao
2008, 34(04): 465-469.
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Numerical simulation and analysis of flow field around a simplified fastback car and aerodynamic noise at some receiving point were conducted using CFD software FLUENT. The pulsating flow field was simulated by the large eddy turbulence model and the momentum equations were discretized with the unbounded central difference scheme. The calculations were performed under three conditions: uniform motion with two running speeds and accelerated motion. The influences of pulsating flow field and aerodynamic noise by uniform motion speed, uniform and accelerated motions were investigated. The results show that with the increase of uniform motion speed, the velocity, sound pressure level corresponding to each frequency and total sound pressure level at the receiving point become bigger, the pressure becomes smaller; At the same motion speed, the velocity, sound pressure level corresponding to each frequency and total sound pressure level in accelerated motion are greater than those in uniform motion, the pressure is smaller.
Simulation of thermal control system of nano satellite based on fuzzy control
Yang Juan, Li Yunze, Wang Jun
2008, 34(04): 470-473.
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A thermal system dynamic characteristics equation of a spherical nano satellite was built. And its temperature model was established after system steady temperatures were determined. A fuzzy logic controller was designed and combined it with the temperature model to complete the whole thermal control system. ±50% step interference signals were input respectively to simulate the nano satellite-s temperature changes, when instrument heat source changed and the endotherm from sun radiation by satellite surface and radiator changed. The simulation was carried, and the curves were plotted to be compared with the results had got without any controller. The simulation results show that fuzzy control technology can control the nano satellite temperature accurately and rapidly, and by using fuzzy control method, many good qualities ( such as good robust , insensitive to parameters changing , high adaptability and short transition process time) can be obtained.
Scheme effect analysis of numerical simulation on hypersonic double-cone flows
Zhang Jing, Yan Chao
2008, 34(04): 474-477.
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The performance of different numerical schemes were studied by simulation of a hypersonic flow past a sharp double cone. The capability of six numerical schemes—Roe FDS(flux difference splitting), van Leer FVS(flux vector splitting), AUSM(advection up-stream splitting method),AUSMDV, AUSM+ and upwind TVD(total variation diminishing) were employed on the simulation of double-cone flow characteristic. The results show that all sorts of spatial discretization schemes have a good discrimination of shock wave, however the discrimination of viscosity vary with the dissipation of schemes evidently. The least dissipative schemes give the best discrimination of viscosity; also the heat transfer extremum turns out to be very sensitive to the dissipation of schemes. Conclusions were got that the smaller the scheme dissipation, the larger the heat transfer extremum, and with its location near the frontal.
Comparison analysis between two kinds of DBL access codes
Jiang Hui, Li Daoben
2008, 34(04): 478-482.
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A new class of generalized large area synchronization (LS) codes named daoben lab (DBL) access codes was presented. DBL access codes are generated from the left or right kronecker product of the LS codes and the extending matrix, and are called DBL left-product codes and DBL right-product codes, respectively. Two kinds of DBL access codes have their own features. The DBL right-product codes are divided into several groups such that the larger zero correlation window (ZCW) between two different code groups can be obtained and the number of available codes is increased. In addition, the aperiodic auto-correlation functions (ACF) and cross-correlation functions(CCF) of the codes within one group are determined by the extending matrix. The DBL left-product codes are also divided into several groups and the ZCW between two different code groups is same as that of LS code and the number of available codes is not increased, but the ZCW is equally as length as the former LS code used to do kronecker product with the orthogonal extending matrix within one group. Computer simulation has also validated the features of two kinds of DBL access codes.
Fingerprint minutia matching algorithm based on ridge alignment
Wang Peng, Zhang Youguang
2008, 34(04): 483-486.
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Focus on the minutia matching algorithm which is important in automated fingerprint identification systems (AFIS). An improvement was made to the fingerprint alignment-based minutia matching algorithm. In the step of extracting minutia associated ridge information, ridge topologic information about bifurcation was extracted to use in the ridge alignment and minutia matching algorithm. The semi-changeable sized boundary box was used to make this algorithm robust to nonlinear deformation between fingerprint images. A new reference variable was introduced to compute and compare the similar degree of ridges; it can solve the problem of reference point pair selection with lower computational cost and faster convergent velocity of matching algorithm. Ridge alignment process and minutia matching algorithm were combined together, a simple and effective method was put forward in the alignment and matching algorithm. The experimental results show that the new method can greatly improve the matching speed and also develop the system-s performance with less resource engaged.

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