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2009 Vol. 35, No. 3

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Small unmanned aerial vehicle for polar research
Lei Xusheng, Wang Ting, Liang Jianhong, Wang Tianmiao
2009, 35(3): 267-271.
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Focusing on the high wind disturbance in the polar environment, an adaptive Kalman filter algorithm with radial basic function neural network was proposed to improve attitude information performance for the small unmanned aerial vehicle. Based on the unmanned aerial vehicle situation information and sensor information, system adjusts the weights of the measurement noise matrix and the estimated parameters in real time to get precise attitude information. Moreover, a vector field path following algorithm was proposed to improve small unmanned aerial vehicle performance in the following wind, upwind, turning, etc. Using the predefined trajectories as reference, system adjusts course in real time to realize precise path-following control. Finally, the effectiveness of the small unmanned aerial vehicle was proved by a series of simulations and tests. The adaptive Kalman filter can provide long time high precision attitude information for the small unmanned aerial vehicle, and the mean trajectories error is less than 10m in the environment test with 6 degree wind disturbance. The small unmanned aerial vehicle successfully realized the research tasks in south polar research.
Feasibility study of MHD energy bypass scramjet
Zheng Xiaomei, Xu Dajun, Cai Guobiao
2009, 35(3): 272-275.
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The performance of magnetohydrodynamics(MHD) energy bypass scramjet was analyzed using quasi-one dimensional mathematical model. MHD application on ideal and un-ideal scramjet was investigated, the results show that for ideal scramjet there is no need to use MHD devices, for un-ideal scramjet the performance can be improved by the use of MHD energy bypass. Considering about the engineering constraints, such as combustion chamber entry Mach number and the maximum allowable temperature of the entire channel, the performance of scramjet and magneto-plasma-chemical(MPCE) was compared, results show that MHD energy bypass can broaden the flight Mach number range of the engine and improve performance when the vehicle is flying at un-design Mach number or the engine is not perfectly designed. The influence of some important parameters such as load factors and MHD channel pressure coefficients to the performance of the MPCE was analyzed, results show that the optimization of these parameters can increase the specific impulse of the engine but the degree is constrained by the engineering conditions.
Effects of rotating induced forces on fluid flow and heat transfer in square channel
Liu Chuankai, Ding Shuiting, Tao Zhi
2009, 35(3): 276-279.
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Numerical simulations of turbulent flow and heat transfer in a rotating smooth radial outward flow passage were performed with rotation number from 0 to 0.24, density ratio from 0 to 0.22, and fixed Reynolds number of 25000. Effects of Coriolis force and Centrifugal force were analyzed with the three dimensional simulations and the following conclusions were drawn: the tangential component of Coriolis force induces cross stream secondary flow in the form of two-cell pattern, while the radial component of Coriolis force decelerates and accelerates the center bulk flow and the flow in the vicinity of the side wall, respectively. The influence of buoyancy force on flow and heat transfer shows marked dependency on the intensity of the Coriolis force. The predictions reproduce correct physics and show qualitative agreement with the published experimental observations.
Dynamical thermal analysis of microchannel cooling system for in-orbit nano-satellite
Liu Jia, Li Yunze, Wang Jun
2009, 35(3): 280-283.
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Considering the continually rising tendency of the power densities of nano-satellite, MEMS (micro electro mechanical systems)based pumped liquid microchannel cooling system was introduced. Dynamical thermal response model for the temperature changes of both the controlled object and the cooling device was built up by means of the lumped parameter method with reasonable analysis and logical simplification. Based on the nanosatellite inorbit case, the variation rule of the internal electronic equipment and external radiator surfaces were performed by the numerical simulation and calculation. Simulation results indicate that MEMS based on the microchannel cooling system can satisfy the cooling requirements of nano satellite thermal system with high heat flux; the external space heat flux has less affect to the radiator of nano satellite compared with the internal equipment; the modeling methods and algorithm is convenient and reasonable not only for the dynamical temperature calculation and the analysis of nano satellite, but also for the developing of advanced nano-satellite thermal control and thermal management theories and technologies.
CAN modeling and simulation based on OPNET
Li Xiaoting, Ding Fan, Xiong Huagang
2009, 35(3): 284-287.
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To analyze controller area network (CAN) protocol and evaluate CAN network performance, the CAN network modeling method was developed, based on the OPNET network simulation environment. Layered modeling method was adopted to implement CAN node model. Medium access control (MAC) module, error module and deference module were proposed based on function in the MAC sublayer of node model in order to ensure clear system structure. Network response time analysis model and inaccessibility analysis model were implemented using process design separately in MAC module and in error module. Link model and data model were defined and edited. CAN network was configured and simulated according to example model. The agreement of the simulation results with the example model testing results prove this model is valid. Through results analysis of specifically-configured network, CAN network performances were discussed. Independent and editable node model, link model and data model were provided, indicating these models could be used to carry out varied network configuration flexibly and analyze varied network topologies.
Single-phase forced convective heat transfer in swirl microchannels
Xi Youmin, Yu Jianzu, Xie Yongqi, Gao Hongxia
2009, 35(3): 288-291.
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The experiment of heat transfer in four swirl microchannel test pieces was conducted with ethylene glycol solution of 30% (volume concentration). The test pieces- cross section was rectangular with width 0.3mm and different depth. Constant heat flux was adopted as heating manner. Each test piece was made of copper and contained six microchannels. The heat transfer characteristic of swirl microchannel under the different liquid flux and the heating power was investigated. The influence of microchannel structure and liquid velocity was analyzed. Heat transfer experimental formula was obatined. Heat transfer characteristic was compared with straight microchannel. The result shows that heat transfer performance of swirl microchannel is better than straight microchannel.
Information fusion algorithm in INS/SMNS integrated navigation system
Zhao Jingjing, Wang Y
2009, 35(3): 292-295.
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The problems, such as time alignment, multi-rate filter, unequal interval and measurement delay, were involved when information was fused in inertial navigation system /scene matching navigation system(INS/SMNS)integrated navigation system. In order to solve them, a solution, based on the fact that INS/SMNS integrated navigation system was applied in terminal guidance generally and the relation between Kalman filter and measurement, was presented. Extrapolation was applied to the align time, the system was discretized in unequal interval and the multi-rate filter was designed, the measure delay was eliminated by software. Analyzing the filtering accuracy of the common Kalman filter, the Kalman filter without measurement delay and the presented solution, the results demonstrate that the method presented here has high accuracy.
Dynamics analysis and modeling of helicopter rotor test-bed
Xue Liangru, Wang Shaoping
2009, 35(3): 296-299.
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The helicopter rotor test-bed is one of the main equipments to test the helicopter rotors. The testing effect and control accuracy can be improved by making kinetics analysis and building the model of the helicopter rotor test-bed. The helicopter rotor test-bed structure and functions were introduced, and the pitch link loads was simplified. The dynamic model of the helicopter rotor test-bed was built by making the force analysis of the swash plate. According to the simulation of the hydraulic model and test-bed model, the dynamic response and interactive coupling influence were studied in the different gestures of the rotor system. The system responses were made in different load characteristics. The modeling and analysis of the test-bed can give a theoretical support on the control of rotor gesture and improvement of the excitation accuracy, and be helpful for the design of the test-bed and control system.
Solution for SMP cluster virtualization
Peng Jinbing, Long Xiang, Xiao Limin
2009, 35(3): 300-303.
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Cluster is a kind of important parallel computer architecture with the advantages of low cost and good scalability, but also with the pitfalls of poor programmability and difficult administration. By means of the virtualization technologies, a distributed cluster could be abstracted to a share-memory virtual machine for supporting the share-memory programming mode, so that the pitfalls of a cluster could be overcome. Currently, there were only a few primary study results in this area, and they could not support the virtualization of SMP (symmetric multiprocessor) clusters. A novel solution was presented,which was constructing a DVMM (distributed virtual machine monitor) on a SMP cluster based on hardware-assisted virtualization technologies. The DVMM contained some symmetrical and cooperative VMMs distributed on multi-node. The cooperation among the VMMs virtualized the distributed hardware resources of the cluster. Thus, the DVMM could support an unmodified legacy OS (operating system) to run transparently on a SMP cluster. Compared with the related works, our solution has some advantages of good transparence, high performance, wide usage and easy implementation.
Broadband fiber source mean-wavelength control with optical power feedback
Yang Yuanhong, Shen Tong, Zhao Guancheng
2009, 35(3): 304-307.
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To promote the broadband fiber source temperature stability, the mean-wavelength stability of broadband fiber source was analyzed and the dependence between the mean-wavelength and the output optical power was revealed based on the simulation and experiment study on the change of mean-wavelength and output power under different pump optical power. A mean-wavelength control scheme was proposed based on the dependent mathematical model among with mean-wavelength, feedback power and environmental temperature by temperature experiment. The mean-wavelength precision control was realized by taking small part power from fiber source output as feedback signal and adjusting the pump power by changing drive current. A prototype fiber source was made and tested. The result approves this scheme and 0.3×10-6℃-1 mean-wavelength stability within -45~70℃ was achieved.
Calculation of thermal load and impact factor analysis for hypersonic vehicle
Zhang Lizhen, Wang Xiaoming, Dong Sujun, Wang Jun
2009, 35(3): 308-312.
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Endothermal thermal protection system (TPS) and liquid N2 heat sink were chosen to calculate the characteristics of thermal control system (TCS) in hypersonic vehicle. The methods of radiation balance and double lumped parameter were adopted to obtain the thermodynamic model of adiabatic layer and cabin air temperature. Therefore, aeroheating, adiabatic layer heat transfer and cabin air temperature were decoupled. On the basis of flight profile of X-34 hypersonic vehicle, the thermal load of avionics bay was calculated. Besides, the influence of adiabatic layer, cooling gas velocity and liquid N2 amount on cabin air as well as the equipment temperature were analyzed. The results show that this method could get the response characteristics of heat transfer sections, which played an important part in the primary stage of hypersonic vehicle design.
Numerical analysis of flow and heat transfer characteristics of Y-fractal-link micro channel networks
Xu Guoqiang, Wang Meng, Wu Hong, Tao Zhi
2009, 35(3): 313-317.
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A new fractal structure, Y-fractal-link micro channel network, was proposed for cooling the inside of cubic chip. Numerical simulations of laminar heat and flow transfer were conducted for both Y-fractal-link micro channel network and straight parallel micro channel network. In addition, the optimization of this new structure was discussed with some important parameters. Results reveal that with the same convective surface area and hydraulic diameter, Y-fractal-link micro channel network could significantly improve the heat transfer performance of the heat sink and decrease the pressure drop through the micro channel, so this new structure will be useful for cooling devices with high thermal load. In the range of study, the best integrative performance of Y-fractal-link micro channel heat sink is obtained when the number of branching levels is 3; the bifurcation angle is 60 and the number of branches at each level is 2. These results are beneficial to the design and improvement of heat sink configuration.
Numerical simulation on compressive yielding behavior of closed-cell metal foam with low density
Lu Zixing, Zhang Jialei
2009, 35(3): 318-321.
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It is an important means to simulate the deformation process of metal foam with low density numerically for investigating their mechanical behavior and failure. Based on the geometric model of Kelvin containing multiple cells, the finite element method was used to obtain the compressive yield strengths and to simulate the deformation curves of closed-cell metal foams. The deformation processes of the Kelvin foam models were simulated at the same time. During the calculation, the material properties of nonlinearity and geometric nonlinearity were taken into account,also, the influences of the number of cells on the foam properties were discussed. In order to investigate their influences on the mechanical behaviors of foams, the two constitute relations, perfect elastic-plastic relation and linearly hardening elastic-plastic relation, were adopted. The results show that the calculated values agree well with the theoretical results ever reported by other researchers, but the values are higher than the former experimental results.
Missile control systems design based on second order sliding mode theory
Chen Jie, Gu Wenjin, Zhou Shaolei
2009, 35(3): 322-325.
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As a novel nonlinear control method, over-load control has quickly developed in the field of missile control law design in the recent years, but during the design of the skid-to-turn(STT) supersonic cruise missile pitch channel control system based on over-load control, the system exits non-minimum phase phenomena between over-load output and rudder input, that causes zero dynamic unstable. The output-redefinition method was adopted to translate system state, regard the internal states steady-state response as the expected reference trace, translate output track into state track, that guaranteed zero dynamic stable. The controller was designed by adopting second order sliding mode to eliminate inherence chatter of sliding mode control. Lyapunov function was used to determine the above controller parameter to guarantee the tracing of original system output, the attack angle observer was designed to deal with the problem of incomplete obtainable system state that was induced by attack angle uneasily measured. Simulation results show that the approach can increase robustness and stability, the system owns better dynamic performance.
Two interval sculling compensation algorithm based on duality principle
Yu Yang, Zhang Hongyue
2009, 35(3): 326-329.
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The sculling compensation algorithms are designed generally using minimal error theory, under the typical sculling motion. The coning compensation algorithms can be designed using Goodman-Robinson finite rotations theory besides minimal error theory. An two intervals accurate sculling compensation algorithm was deduced based on duality principle and two intervals correct coning compensation algorithm which was obtained using Goodman-Robinson finite rotations theory. Under the typical sculling motion, some digital simulations about this new algorithm were completed and some comparisons with two intervals optimum sculling compensation algorithm were taken. The simulation results show that the new two intervals sculling compensation algorithm has fine accuracy.
Multi-machine scheduling problem with multi-time windows: model and algorithm
Liu Wei, Meng Xin, Zheng Jianhua
2009, 35(3): 330-333.
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With regard to the multi-machine scheduling problem with multi-time windows for minimizing the cost,how to solve the question quickly and effectively remains to be a hard problem in combination optimization research field. Firstly two models were established to describe the simplified questions during the study of optimization,including an integer programming(IP)model and a constraint programming (CP) model. By discussing the defects of the IP model and CP model,a new hybrid IP-CP model was constructed. In addition,a heuristic algorithm was applied to solve the hybrid IP-CP model. Result of the tests indicate that the hybrid IP-CP model and heuristic algorithm developed are proved to be feasible and effective for the multi-machine scheduling problem with multi-time windows,especially for the large-scale scheduling problem.
Mismatching judgment in simplex optimization for ICCP algorithm
Yang Yong, Wang Kedong
2009, 35(3): 334-337.
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Iterative closest contour point(ICCP) algorithm was applied into map aided navigation, in which simplex algorithm was used to estimate the optimal trace of vehicle. However, simplex algorithm was usually convergent at the local optimization so that there was mismatching or even diverging. The rule of mismatching judgment for ICCP was established to reduce mismatching probability. The rule of mismatching judgment for ICCP was established by probability data association filter(PDAF). Simulation shows that PDAF improves the convergence and precision compared with the ICCP algorithm without mismatching judgment, and its mismatching probability decreases 30 percent compared with M/N method. The PDAF method for mismatching judgment increases precision and stabilization.
Block diagram modeling and control of electro-hydrostatic actuator
Kang Rongjie, Jiao Zongxia, Wang Shaoping
2009, 35(3): 338-341.
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Power-by-wire (PBW) actuation is the future direction of flight control system in which the need for a central hydraulic system is eliminated. The electro-hydrostatic actuator (EHA) is a kind of PBW actuator that converts the electrical power into local hydraulic power and combines the benefits of the conventional hydraulic system and the direct drive electrical actuators. Based on the mathematic equations, all the EHA components were modeled by the block diagrams and assembled to a fixed-displacement variable-speed architecture, which contained the refeeding circuit and the friction. Furthermore, the single proportion integration differentiation (PID) controller, cascade PID controller and state feedback controller are designed for comparison analysis that focused on the system stability, stiffness and dynamic characteristics. The simulation results prove that the state feedback controller along with dynamic pressure feedback strategy efficiently improves the static and dynamic performance of EHA.
Parallel algorithm of anomalies detection in hyperspectral image with projection pursuit
Wang Wei, Zhao Huijie, Dong Chao
2009, 35(3): 342-346.
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Projection pursiut can extract non-Gaussian structure in hyperspectral data to reveal the anomalies information, but searching the best projection directions is a computational intensive task. To improve the process efficiency, a parallel process algorithm under cluster system was presented. The combination of skewness and kurtosis was selected as projection index (PI). Using all the pixels- spectral as a special projection dierection set and searching the best projection directions in it. While parallel computing the PI value for each candidate dierection, the hyperspectral data was distributed to each computing node after partitioned evenly. After projecting each data subblock to a candidate direction in parallel, the index computation was transformed and decomposed. This makes all the data needed during index computation be in local memory for each node and decreases the communication. Furthermore, a "be host in turn" method was put forward to improve the degree of load balance. Using an operative modular imaging spectrometer data to test the efficiency on cluster, the results show that the parallel algorithm achieves good parallel performance.
On-spot camera calibration method based on flexible planar target
Yu Minglang, Wei Zhenzhong, Sun Junhu
2009, 35(3): 347-350.
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A flexible planar target method was proposed to perform on-spot camera calibration. In this method, only several characteristic points with known 3D coordinates are needed to be preset on the planar target, and among these preset characteristic points, the ones which are collinear could determine a straight line, so a number of straight lines can be determined. Furthermore, under the perspective projecting transformation, striaight line and the intersection point of two straight lines are invariables. So, based on the above mentioned properties, a great amount of points which differ from the preset characteristic points on the planar target can be obtained for on-spot camera calibration. Detailed error analysis of the obtained calibration points was conducted based on error propagation law. A real flexible planar target, which is of the size of 100mm×100mm and the accuracy of 0.01mm, was made to perform the experiments of on-spot camera calibration, and the calibration accuracy is 0.032mm.
Numerical method to simulate rime ice accretions on an airfoil
Zhang Qiang, Cao Yihua, Li Dong
2009, 35(3): 351-355.
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Based on the Eulerian two-phase flow theory, a numerical method to simulate rime ice accretions on an airfoil has been developed. The semi-implicit method for pressure linked equations (SIMPLE) algorithm on a collocated grid was employed to solve the governing equations for the airflow. In order to simulate droplets impinging on an airfoil, a permeable wall was proposed to solve the governing equations for supercooled droplets. The collection efficiency and impingement limits were obtained from the droplets- flowfield. The process of ice accretion was simulated using the assumption that ice accumulates layer-by-layer and the ice shape was built with the assumption that ice grows in the direction normal to the airfoil surface. The rime ice accretions on a NACA 0012 airfoil at 0° and 40° angles of attack have been investigated and there is agreement between the simulated results and experimental data. A conclusion that ice accretions degrade the airfoil-s aerodynamic performance can be drawn based on the analysis of pressure distribution along the iced airfoil.
Entropy correction analyses for Roe scheme
Zhou Yu, Yan Chao
2009, 35(3): 356-360.
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Three types’ entropy fix formulations for the Roe scheme were analyzed in theory and assessed by three numerical tests which were shock tube problem, step flow and double Mach reflection. The results show that "Carbuncle phenomena" occurs when capturing strong shock because of the original Roe scheme-s numerical instability. Muller-s and Harten-Yee-s entropy fix methods introduce numerical dissipation to both shock and non-physical expansion shock processes. The numerical dissipation improves the Roe scheme-s numerical stability and cures "Carbuncle phenomena" entirely for shock case and diffuses the expansion shock completely as well. Harten-Hyman type-s entropy correction formulations do no contribution to shock case and can not cure the "Carbuncle phenomena". They can only fix non-physical expansion processes partially because their numerical dissipation is not large enough. The eigenvalue correction method which directly uses delta replace eigenvalue itself exceeds the traditional method.
Experimental of effect of water mist nozzle injection pressure on fire extinguishing
Yang Lijun, Fu Qingfei, Wang Xiangdong, Liao Shengjie
2009, 35(3): 361-365.
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In order to investigate the effect of water mist nozzle to extinguish heptane fire under different injection pressure, a series of experiments were performed in an enclosed compartment of 4.6m×3.3m×4m with a certain type of water mist nozzle under various injection pressure. Thermocouples tree and gas analyzer were used to measure the temperature and oxygen concentration in the flame. The effect of injection pressure on the affectivity of water mist suppressing pan fire was gained, which provides corresponding experimental foundation for designing water mist system, establishing test standard and developing new product of water mist.
Technique of continuous auto-calibration of redundant strapdown inertial system
Lu Jiazhen, Zhang Chunxi, Zhu Lufeng
2009, 35(3): 366-370.
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A novel continuous auto-calibration technique was presented for redundant strapdown inertial navigation systems. Principles of the proposed technique were based on strapdown system error models, which indicated that velocity errors from the system could contain information related to inertial sensor errors when rotated along a predefined trajectory. A novel calibration trajectory was designed. All deterministic errors could be accurately estimated through Kalman filtering techniques. Simulation platform for redundant strapdown system was designed to validate efficiency of this technique. Results show that the novel calibration technique outperforms conventional multi-position technique considering its simplicity and precision, which is of great importance for practical applications.
Obstacle climbing analysis and simulation of wheel-legged robot
Chen Diansheng, Huang Yu, Wang Tianmiao
2009, 35(3): 371-375.
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A wheel-legged structure with insectival leg configuration in a ground mobile robot was presented in order to improve the terrain adaptability and obstacle climbing capability of the robot. An optimal wheel-legged configuration which enhances the movement stability of the robot was selected. The obstacle climbing performance for the robot configuration under unstructured environment was analyzed, theoretically proving that this wheel-legged structure possesses good obstacle climbing ability and stability. Kinematic simulation using ADAMS (automatic dynamic analysis of mechanical systems) validates the strong obstacle climbing capability of the robot that can successfully climb over a vertical barrier whose height is 1.2 times of the wheel-leg radius, which proves the feasibility of the wheel-legs structure and the effectiveness of the obstacle climbing principle, laying a solid basis for future research of wheel-legged robots.
Paradox of set theory-universal logic
Du Guoping, Wang Hongguang, Li Na, Zhu Wujia
2009, 35(3): 376-379.
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A general formal language in which the value of formulas can be recursively defined can be given by a sextuple-model for n(2≤n≤n )-valued logic. It constitutes a universal logic system UL 1, which characterizes this kind of logic. Connectives like abstract negation, abstract implication and abstract equivalence can be defined in the system. They are the generalization of negation, implication and equivalence in two valued logic. Applying these connectives, the general forms of Russellian sets-making predicate and Curryian sets-making predicate were developed. In addition, a new type of set-making predicate which only contains equivalence was developed. Applying these three kinds of sets-making predicates, abstraction principle led to paradoxes in general system of finite valued logic, countable infinite valued logic and uncountable infinite valued logic.
Avian radar system based on two scanning modes
Chen Weishi, Ning Huansheng, Li Jing, Mao Xia
2009, 35(3): 380-383.
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State of arts of researches on avian radar systems were introduced, including large avian radar system represented by avian hazard advisory system (AHAS) and airport-based avian radar system represented by Accipiter. An avian radar experimental system was built based on X-band marine radar, and its bird detection feasibility was confirmed separately by operation in alternating horizontal and vertical position for the survey. Two series of avian radar images, which were collected under two scanning modes, were processed respectively by bird target extraction algorithm. After processing of background subtraction, noise suppression, target information extraction and data fusion, avian information was extracted from raw radar images and combined with satellite map or height coordinate system, so flying bird targets distribution situation in survey region was shown visually by fusion images. Finally, performances of avian radar systems at home and abroad were compared and analyzed.
Circuit for close-loop capacitive micro-accelerometers
Song Xing, Fang Jiancheng, Sheng Wei
2009, 35(3): 384-388.
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A circuit to detect the micro-differential capacitance of micro-silicon inertia sensors was designed,which can be successfully applied in the capacitive MEMS(micro electro mechanical system) accelerometer,especially in the sandwich structure MEMS accelerometers with differential capacitance．The good linearity in large measurement range and high capacitance resolution was achieved by restraining common-mode noise, bias voltage and nonlinearity of voltage output using technologies, such as improving symmetry of rectangle wave source, equi-potential shielding action, coherent demodulation and electrostatic re-balance. The circuit is simple, its linearity, and ability of anti-disturbance are good, and it could be integrated easily. Experiment results show that the measurement range of the accelerometer is ±15g and the capacitance resolution can reach 10-16F.
Numerical simulation of laser bending process
Wang Xiufeng, Guo Xiaoli, Chen Guangnan, Jurgen Silvanus
2009, 35(3): 389-392.
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Laser bending process was numerically simulated by the FEM software of MSC.Marc. The experiment results were compared with the simulation ones, and the temperature and displacement curves of experiment and calculation were in good accordance. The comparison indicates that, calculated model is regarded as correct and the calculated process is considered to be credible, and calculated result will lay foundation for chosen laser parameters. More irradiation paths influence on displacement effect was discussed by numerical simulation. Conclusions show that the order and direction of irradiation paths have a huge influence on displacement effect of specimen. The best type is regarded as alternate irradiation path with contrary directions from fixation to the end of free so as to gain uniform displacement along the width direction. At the same time, it provides theoretical basis for the chosen of irradiation paths of laser bending stiffened sheet metal.

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