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2005 Vol. 31, No. 03

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Trajectory control logic of space exploration rocket required to arrive given site with zero speed at given time
Dong Yunfeng, Xiao Yelun
2005, 31(03): 265-269.
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The special space exploration rocket is launched to rendezvous with the celestial body flying around earth, the absolute velocity of rocket should be zero at rendezvous time in order to satisfy the observe requirement. The ideal rendezvous orbit was designed before launch based on the orbit of the celestial body and launch site. The orbit parameters were loaded to onboard computer of rocket. After launch, the inertial navigation system was used to measure the rocket position and velocity, the thruster fire direction was adjusted try to eliminate the flight orbit errors. The several coordinated was defined and rocket orbit dynamical equation was created. The ideal rendezvous time, launch time and rendezvous point in space were studied. The trajectory control logic given during the thruster force is available. The error signal is decomposed into time error, altitude error, north-south error and east-west error in local horizontal frame. Position and velocity shift can be set to reduce the orbit drift caused by perturbation. The feasibility of control logic is verified by computer numerical simulation.
Hypersonic aerothermoelastic analysis of wings
Wu Zhigang, Hui Junpeng, Yang Chao
2005, 31(03): 270-273.
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A hierarchical solution process for thermal flutter analysis is presented to dealing with the aero-thermo-elastic dynamic problems of hypersonic wings. Firstly, the natural dynamic characteristics of structures under thermal circumstances were analyzed. And then the hypersonic unsteady aerodynamics were calculated by using van Dyke piston theory. Finally the flutter equations were solved by p-k method. Numerical calculation and comparison are executed on two wings, one was an all-moved rudder, another was a low aspect-ratio wing with root fixed. The results illustrate that both the natural dynamics and the flutter characteristics of wings may vary duo to aerodynamic heating. Especially for the low aspect-ratio wing with root fixed, as the results of the thermal effect, its torsional stiffness decrease greatly, and so the bending-torsion flutter critical speed declines sharply.
Error matching principle for heat transfer calculations in hypersonic flow simulations
Xie Jinrui, Wu Songping, Wang Hao
2005, 31(03): 274-277.
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An error matching principle, which is base on the error analysis of the computations with high-aspect-ratio grids, is derived for the finite difference simulation of the viscous boundary layer flows. The high- aspect-ratio grids were commonly used in numerical simulations of the viscous boundary layer flows and the main calculation error was always correlated to the aspect ratio of the grids. The principle above could be used to keep the same degree of the calculation error in spatial directions respectively. The error matching principle given was verified by the numerical simulation of the hypersonic flows over a blunt-cone. The flow field and the surface heat transfer rate were calculated in the numerical simulation. The results show that the error matching principle is great benefit to generate optimal grids. The optimal grids followed the error matching principle can minimize the error and improve the computational efficiency. At the same time, the accurate calculation of flow field and the surface heat transfer rate are benefited from the match of errors.
Study and application of aircraft configuration management
Yu Yong, Fan Yuqing
2005, 31(03): 278-283.
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To meet the complication, diversification and serialization of modern aircraft, and to guarantee the consistency, integrity and trackability of product data during the process of aircraft digital design and manufacturing, the process of aircraft configuration management and control were studied. The importance of configuration management technology in the whole lifecycle of aircraft design and manufacturing was emphasized and the definition of configuration was confirmed. While differences of configuration and BOM (bill of material) views were given, and the BOM views were EBOM (engineering bill of material), PBOM (process bill of material), MBOM (manufacturing bill of material) etc. Four key technologies of configuration management and control were proposed and analyzed referring to the simplified configuration management of boeing ideas. The four technologies were as follows:from drawing based to part based management, modularization of aircraft product structure items, simplified effectivity management by effectivity of module controlling the aircraft configuration, enhanced version control. The useful application solutions of these four technologies were given.
Research on the production of the navigation data of high dynamic GPS signal simulator
Zhang Bochuan, Chang Qing, Zhang Qishan, Kou Yanhong
2005, 31(03): 284-287.
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For the purpose of testing the performance of GPS(global positioning system) receivers, a GPS signal simulator is needed that can emulate the real GPS signals under all kinds of conditions. The high dynamic multi-channel GPS signal simulator device consists of hardware, computer and software. The software comprises the satellite navigation parameters calculation module, the target trajectory calculation module, the error calculation module and etc.Producing functional module of navigation data is a key technique that the high dynamic GPS signal simulator must solve. The physical meaning of the three parameters of satellite’s clock and the production model of the ephemeris were given. According to these parameters and their corresponding time parameters, Navigation data could be produced. By the procedure simulating and validating it with the navigation data, the results show that ephemeris and almanac correspond to the rules of the satellite’s arrangement.
Shaking table test on ship lifts model with roof MR damper isolation system
Lü Mingyun, Mingyun Wu, Qu Weilian
2005, 31(03): 288-292.
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The sudden stiffness change on the top of tube towers of ship lifts caused the intensive seismic whipping effect to the top machinery building. To suppress the whipping effect, a roof MRD (magnetorhelogical damper) isolation system were presented. The structure model of ship lifts and MRD isolation system designed, the shaking table tests were carried on a ship lifts structure model with and without the roof MRD respectively. The dynamic characteristics and the responses were compared for these two shaking model. Test results show that the roof MRD isolation system changed the dynamic characteristics of the model structure, the proposed control system is quite valid in reducing seismic responses of top building of the model structure. The validity of the numerical model and analysis method for roof MRD isolation system were verified by the comparisons between the results of the shaking table tests and numerical analysis.
Development of a reaction-diffusion model for erosion and identification of the associated diffusion coefficient
Wang Hengyu, Lee Chunhian
2005, 31(03): 293-297.
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It was proposed that the adsorption (including both physical and chemical) was the principal mechanism for AO(atomic oxygen) in LEO(low earth orbit) interactingwith surface materials. The remaining secondary physical or chemical mechanisms could be included into the principal mechanism. The reaction-diffusion equation of erosion could thus be constructed. In addition, with the aid of the classical theory of collision dynamics molecules, one could verify that the physical erosion term in the reaction-diffusion equation happened to be higher order and could be neglected. The diffusion coefficient followed from Eyring’s theory of absolute rates. Numerical simulations of AO effects over the space material Kapton were conducted to validate the model. The numerical results on thickness losses and a 2-D undercutting of Kapton in LEO environment were presented. The simulation results fit NASA’s flight test data well within a proper error range.
Extended role-based access control model
Xue Wei, Huai Jinpeng
2005, 31(03): 298-302.
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An extended RBAC(role based access control) model, RTBAC (role & task based access control) model was presented. The model introduced the notions of task and task instance into RBAC96 model, formally defined the hierarchies of tasks and task instances, specified the relationships between traditional sessions and task instances as well as the relationships between task instances and permissions. Several assistant functions were defined. The model could be used to depict daily business procedures and related access control policies more naturally, so was more suitable for distributed collaborative applications, especially for workflows and service compositions. Based on this model, a new dynamic separation of duty constraint, namely task-based dynamic separation of duty constraint,was formally defined and compared with traditional dynamic separation of duty constraints using a typical example. The new constraint can specify access control related system runtime context more accurately. It can increase the efficiency of access control at runtime.
Analysis of effects of low Reynold’s number on small turbofan engine
Tang Hailong, Zhu Zhili, Luo Anyang, Zeng Yuanjiang
2005, 31(03): 303-306.
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Problem caused by low Reynold’s number is one of main factors affect performance of high altitude endurance unmaned vehicle engines. Effects of low Reynold’s number on a small high bypass turbofan engine were discussed.The effects can make the performance of the engine’s components change when Reynold’s number decrease to some extend. Inlet blade chord Reynold’s Number of booster and low pressure turbine is lower than that of other components of the engine, and will be affected strongly with flight altitude increase and flight velocity decrease. The reduction of engine’s performance is due to component performance decline and engine re-match resulting from low Reynold’s effects on component performance. Not only efficiency of component, but also reduction of component’s mass flow, lead to the performance degradation of the engine. The rotator speed reduction (because of turbine inlet total temperature’s limit) enhances the low Reynold’s effects and hence reducing engine’s performance, engine thrust decrease rapidly, but increase of engine bypass ratio partly compensate the rise of specific fuel consumption caused by the component performance decline.
Analysis of stress in winding fiber-optic ring
Meng Zhaokui, Zhang Chunxi, Yang Yuanhong, Xu Yonggang
2005, 31(03): 307-310.
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Some opinions to coiling the optic fiber ring were expatiated from two facets that quadrupole symmetry winding method and stress control which was emphasis and nodus during winding. These views were concluded from the practical winding experiments, and it should be useful to improve the winding quality. The strain distributing in the polarization-maintaining-fiber was measured and analyzed by BOTDR(brillouin optical time domain reflectometer). It shows from the results of the measurement and analysis that BOTDR can be used to filtrate and analyze the optic fiber and optic fiber ring strain. It shows from the research, experiment and application, the stress control during winding a coil is the key fact, it should be remained in a proper range.
All-sky autonomous star map identification algorithm based on Delaunay triangulation cutting algorithm
Fang Jiancheng, Quan Wei, Meng Xiaohong
2005, 31(03): 311-315.
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In the field of geophysical model building,Delaunay triangulation cutting algorithm has been widely used because of having a very important characteristic which is the result of this triangulation cutting method being unique in a specifically set of points.This character was adopted, the algorithm to identify star map for the first time was used.Making use of the invariability of cutting in all-sky star atlas and adopting the boundary recursive method for constrained triangulation of surfaces,the guidance stars database which was arranged under specific rules and whose size was comparatively small was constructed;the recognition algorithm utilized the result generated by Delaunay cutting star map in a specified field of view to match and identify quickly.The simulation results show that compared with the current star map identification algorithms,this algorithm has a high rate of discrimination,the advantages of real-time properties and robust;and it only needs a small content database and searches more rapidly.
Application of algorithm of intersection between lines and random curves in calculating grain size
Yu Yang, Liu Erli, Zhou Tietao, Liu Peiying
2005, 31(03): 316-320.
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The feasibility of computerization problem of grain size measuration was discussed from the viewpoint of Material Science. The average diameter method was adopted to compute the grain size for an image processed about grain-edge. Based on the Freeman code principle, the differences between the method for seeking the intersection between lines and curves in Euclidean space and that in Pan-Euclidean space were analyzed, and the conception of pseudo-intersection was proposed, the solution for calculating intersection was advanced theoretically. the factors that influence the computation of the intersections between lines and curves were analyzed from the viewpoint of computer graphics, and the corresponding solution in algorithm was provided. The results of calculation are identical with the experimental result finally; the method is approved to be swift and efficient, and can be used in engineering analysis.
Novel image denoising algorithm based on bispectral reconstruction
Jiang Hong, Wu Lijiang
2005, 31(03): 321-325.
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A novel image denoising algorithm based on the bi-spectral reconstruction was proposed. The basic idea of this new algorithm was:higher order statistics was not sensitive to the Gaussian noise. First of all, this new algorithm would calculate the higher order spectrum of the image, and theoretically this higher order spectrum would not include the Gaussian noise any more. Secondly, it would reconstruct the amplitude and phase information of this processed image by the higher order spectrum. Finally, it would get the denoised image by transforming to the spatial domain. This new algorithm was the algorithm of transformation and reconstruction in higher order spectrum. Simulation results and analysis indicate that this new algorithm could solve the contradiction between reducing noise and reserving the image detail so that in views of both visual quality and quantitative analysis, the new algorithm is better than the median-value filtering algorithm and the higher order cumulant algorithm.
Path planning for astronaut translation by means of continuous handrails during extravehicular activity
Yang Feng, Ding Li, Yang Chunxin, Yuan Xiugan
2005, 31(03): 326-330.
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It is usually requested that astronauts move from one worksite to another during the extravehicular activity. An efficient and robust technique for generating global motion path for moving astronauts in the working environment utilizing heuristic search algorithm, A* algorithm, was proposed. Initially, the working space was discretized to some cells with specific volume and physical dimension. An obstacle-free cell path according to Manhattan metric was generated between any two cells. This path was planned based on the criterion that ensures the path was the shortest one amongst many feasible paths. A practical path was planned for a common extravehicular activity in which the astronaut moved from a module to another through an aisle by means of consecutive handrails. The planned path can provide some guidelines for designing the installation site of handrails in order to reduce the working time, lower astronaut energy consumption, and promote the operating efficiency of extravehicular activity.
Closed-loop system of silicon resonant pressure micro-sensor
Li Haijuan, Zhou Haomin
2005, 31(03): 331-335.
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When the silicon resonant pressure micro-sensor works in the self-oscillation close-loop system with thermal-excited and resistor detected, its output has a problem of dreadfully weak signal of micro-sensor. SNR( signal noise ratio) is as low as 10-3, for the system used frequency-equaled signal to excite micro-sensor to get its syntony, as well caused the damaging coupling disturbance. PLL(phase-locked loop) principle and frequency-divided technique were used to design the double closed-loop control circuit of micro-sensor to avoid those. Micro-sensor worked in the outside loop and PLL made the inside loop. The frequency output of micro-sensor had frequency-equaled exciting signal and duple frequency true signal, after multilevel power amplification multiplied duple frequency output of PLL to achieve frequency dividing, adjusting the system state parameters made closed-loop available and phase locking. Results show that the closed-loop system of micro-sensor works effectively based PLL principle and frequency-divided technique and the low SNR gets developed.
Framework design of embedded software testing development environment
Zhang Liang, Liu Bin, Lu Minyan
2005, 31(03): 336-340.
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By adopting the idea of software design reuse, framework design for an embedded software simulation testing environment can offer an efficient solution to construct testing environment without largely changing the architecture of testing environment when testing different embedded software, and hence reduce development time and cost. The software development process using ideas of framework design was discussed and then applied to the testing environment’s development. Based on the general analysis of existing embedded software simulation testing environment, three main components were identified to be the basic parts of testing environment. The basic function of testing development environment was defined , which was an important part of the testing environment. A concrete framework was designed by using the unified modeling language profile for framework UML-F, a specific language for framework design. An adaptation scheme was put forward for a testing development environment that was successfully developed. The framework studied has been applied in a practical project.
Embedded ARM processor FPGA technology in star sensor
Yin Na, Jiang Jie, Zhang Guangjun
2005, 31(03): 341-345.
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An ARM(advanced RISC machine)embedded FPGA(field programmable gate arrays)chip - EPXA10 was introduced. A research of image acquisition and star position locating based on this technology were done and the accomplishment was achieved. The driving of the CMOS(complementary metal-oxide-semiconductor transistor) image sensor and the pre-processing of the digital image were accomplished in FPGA part of the EPXA10. The star position locating algorithm was achieved in ARM part of the EPXA10. The programs of serial port communication and the image display were realized by Visual C+ + language. The clear picture taken by the CMOS image sensor and the locating result were presented. By comparing the locating results of ARM and PC(personal computer),the result was accurate. The processing speed of the whole system is increased and the complexity, volume and power consumption of the circuit are reduced by adopting an ARM Embedded FPGA.
Structural synthesis method for 4-degrees-of-freedom symmetrical parallel manipulators
Fang Hairong, Fang Yuefa, Guo Sheng
2005, 31(03): 346-350.
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Based on screw theory, the relationship between motion screw system of limbs and constraint screw system of moving platform were analyzed. All possible 5-order motion screw systems of limbs’ structures were enumerated, and then a systematic method was presented for structural synthesis of 4-DOF (4-degrees-of-freedom) parallel manipulators with symmetrical structure. According to their motionproperty, using this method, a serial of manipulators with 3-translation and 1-rotation mobility that had different structures were gotten. Results show that method has simple expression form for structural synthesis of lower mobility parallel manipulators relying on the relationship between motion and constraints that both have the screw models for easily analyzing. Results also show that the method can be easily applied for structural synthesis, and can be efficiently and fleetly used for structural synthesis of symmetrical mechanisms based on the given motion property of moving platform. It establishes the foundation for optimizing design for lower mobility parallel manipulators.
Numerical simulation of space debris hypervelocity impact using SPH method
Yan Xiaojun, Zhang Yuzhu, Nie Jingxu
2005, 31(03): 351-354.
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The SPH(smoothed particle hydrodynamics) was applied to simulate the problems in Whipple structure hypervelocity impact. In modeling the structure, the SPH and FEM(finite element method) discretizations were used simultaneously to reduce the CPU time, and this was very convenient and advantageous in practical engineering design when more CPU time consuming. SPH nodes were employed to model the area where the deformation was larger and likely to be perforated by the projectile. FEM nodes were employed to model the area with small deformation. The calculation results indicate that the fist bumper was perforated and the main wall cratered. Those results were compared with the test results from the literature and indicated fairly good agreement with each other. It demonstrates that SPH method is helpful and efficient in understanding the hypervelocity impact phenomena and fracture mechanism in the space debris hypervelocity impact problem.
Influence of linear leaf springs’ hysteresis behavior on vehicle’s ride
Ding Nenggen, Pan Weimin, Liu Zhuqing
2005, 31(03): 355-358.
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A method was investigated to select proper damping coefficients of the damper used for the leaf spring suspension, based on the analysis of the influence of leaf springs' hesteresis behavior on vehicle’s riding on different kinds of roads. Based on a quarter vehicle model, the root of mean squared acceleration of sprung mass was analyzed on different grades of roads with and without consideration of leaf springs' hysteresis behavior. The model was solved in time domain due to its nonlinearities. Both randomly produced road data and a group of real road data were used as inputs of the model. Results show the hysteresis behavior is more harmful to vehicle’s riding comfort on a high quality road than on a poor quality road, and therefore the damping coefficients of dampers should be selected according to road grades. For vehicles with leaf spring suspensions, the dampers’ damping ratios for jounce travel should be 0.1~0.2 and that for rebound travel be 0.2~0.3.
Setup and application of a wetting property measuring instrument
Zhang Zuoguang, Chen Liang, Li Min, Sun Zhijie
2005, 31(03): 359-362.
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A new wettablity instrument was developed according to the fabrication characteristic of composites, which could measure the mass increase in fibres penetrated by resins. The instrument was composed of two parts. One was the wicking mass testing system and the other was a temperature-controlled system. It could measure the capillary impregnation of liquids in the fibre bundles with various fibre volume fractions under different temperatures. The instrument was evaluated and adjusted. Based on this, the wetting of resins in glass fibres and carbon fibres were studied. Effects of the type of fibres, the viscosity of resins and the fibre volume fraction on wicking behaviour were also investigated. The results show that this instrument provides a convenient tool for studying on wettability of the reinforced fibres probe by the resin matrix, which is valuable for guiding parameters in the process of composites.
Explanation of reduced order controller for a class of H∞ singular control problem
Zhong Ruilin, Cheng Peng
2005, 31(03): 363-366.
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The structure character of system transfer matrices can be used to solve a class of singular H∞ control problem and a reduced order H∞ controller can be constructed in explicit form either by linear matrix inequations method or two algebra Riccati equation method. The order of the system H∞ controller can further be reduced by use of system unstable invariant zeros. Based on two algebra Riccati equation method especially the structure of the system Hamilton matrix and system observability theory, the role of invariant zeros in constructing system reduced order controllers was given. That is, by the suitable selection of free parameters of the system H∞ controller, some points which were symmetry with the unstable invariant zeros about the imaginary axis became the stable poles of the system controller which were not observable and could be reduced from the system, thus could get further reduced order controller.
On convergence of formula for forward problem in brain physics
Chen Guo, Li Jing, Wei Chen, Lü Junfang
2005, 31(03): 367-371.
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In brain physics, the forward problem is the process of predicting scalp potentials distribution from known brain electrical source. The convergence of a forward problem algorithm was analyzed and proved through mathematic method for the first time. This formula calculated the scalp potentials distribution of the three layers concentric sphere head model caused by single dipole located at any point within the model. The convergence was further confirmed by numeric simulation. Thus the finite progression could be used to calculate the scalp potentials distribution in stead of the infinitive progression in a certain error range. A study on the convergence speed was conducted too. The result gives a theoretic guarantee for the finite approximation of the formula that is an infinite series. The approximation provides a useful tool for the backward problem, which is the process of predicting brain electrical source from known scalp potentials.
Dynamical modeling and simulation of satellite thermal control system
Li Yunze, Wei Chuanfeng, Yuan Lingshuang, Wang Jun
2005, 31(03): 372-374.
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Modeling and simulation of controlled-object temperature changes are necessary for developing satellite thermal control system. In order to calculate the dynamical properties of satellite thermal control system more easily, the whole satellite was divided into five lumped thermal control nodes, which included satellite's outer surface, heat radiator, indoor environment, key electrical equipment and phase change device. The heat transfer relationship between different nodes and temperature change properties of each part was carefully considered during the node dividing process. Mathematical models for temperature changes of each thermal control node were built and presented. With these dynamical models above, the key temperature changes of satellite, causing by either indoor heat source disturbs or outer side space heat flux varieties, could be calculated more simply and conveniently than using the common unsteady temperature field calculating method. This satisfies the stringent demand of thermal control system's control strategy optimization and its simulation. It's especially useful in developing active thermal control systems.

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