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2009 Vol. 35, No. 6

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Fast data fusion method for MGNC integrated navigation system
Sheng Wei, Tan Liwei
2009, 35(6): 657-660.
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To reduce the computation time of the integrated navigation, an improved algorithm was proposed without model state vector reduction for the micro guidance navigation and control (MGNC) system. The direction cosine matrix was deserved by iterative computation instead of using quaternion as an intermediary. The measurement correction was processed one by one to avoid computing the matrix reciprocal. A triple elements method was proposed based on the sparseness of the transformation matrix while calculating the covariance matrix forecast equation. Mathematical simulation and experiment show that the improved algorithm can provide the same accuracy as the traditional method for navigation and can reduce the filtering calculation time by 34.50%. The method can improve the robustness of the MGNC system and is quite useful in practical application．
Lateral-directional flying quality characteristics of high aspect-ratio combat flying wings
Li Lin, Wang Lixin
2009, 35(6): 661-664.
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The roll and yaw axes flying qualities of high aspect-ratio combat flying wings were assessed, based on MIL-STD-1797A. With the adjustment and improvement provided by the proper-designed flight control system, the closed-loop dynamic response characteristics of flying wings, such as roll mode, spiral mode, roll-spiral coupling, dutch roll mode, lateral acceleration at pilot station and so on, were improved a lot inspite of the differenct configurations, but the static trimming characteristics can not entirely meet the criterion on account of the all-wing configuration. Roll axis and yaw axis control power requirements of roll maneuver, crosswind takeoff and landing, asymmetric thrusts were studied, and in some cases the control power requirements of combat flying wings are quite different with those of the conventional-configuration combat airplanes, due to the disappearance of vertical tail and rudders and the appearance of the new-style control effectors set.
Mathematical model of small diameter condenser pipes
Bai Lizhan, Lin Guiping
2009, 35(6): 665-668.
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Based on the annular flow pattern, the mathematical model of condenser pipes with small diameters was established. The effect of surface tension on the liquid/vapor interface causing the pressure difference between liquid and vapor phases on the same cross section and the interaction between the liquid and vapor phases including the frictional and momentum-transfer shear stresses were considered in the model. The variations of the liquid and vapor phase pressure drops, the thickness of the liquid film, shear stress on the liquid/vapor interface and so on along the pipe length can be obtained by solving the model. Based on the modeling results, the conclusions below can be drawn: the two-phase pressure drop along the pipe length increases nearly linearly; the average velocity of vapor phase first increases and then decreases, but the variation range is small and far bigger than that of liquid phase; the momentum-transfer shear stress increases as the thickness of the liquid film increases, and can not be ignored compared to the frictional shear stress; the convective heat transfer coefficient at the inner wall of the pipe decreases as the thickness of the liquid film increases, but it is still comparatively bigger when the condensation is almost completed.
Disturbance observer based on angular acceleration for gyro gimbal servo system
Xu Xiangbo, Fang Jiancheng
2009, 35(6): 669-672.
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Magnetically suspended control moment gyro (MSCMG) is the primary attitude actuator of large spacecraft, and the MSCMG gimbal servo system control precision is one of the main factors which affect gyroscopic torque accuracy. In order to enhance the MSCMG gimbal servo system disturbance suppression ability and control precision, a disturbance observer based on angular acceleration for MSCMG gimbal servo system was proposed. Using angle, Kalman filter estimates the velocity, which was sent to the state observer to acquire the precise angular acceleration. Angular acceleration and current were used as inputs of disturbance observer to obtain compensatory current. Then the compensatory current was sent to the input of current loop to compensate various disturbances. The disturbance observer has characteristics of simple structure and good disturbance suppression ability. The experimental result shows that this method can effectively improve the velocity precision and stability of the MSCMG gimbal servo system.
Genetic algorithm-based decomposition method for multidisciplinary design optimization
Chen Yunxia, Gao Jieping, Xia Huafeng, Zeng Shengkui
2009, 35(6): 673-677.
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Based on the analyzing of current methods of solving task decomposition problem in MDO, such as enumerate algorithm, clustering identification method, branch and bound method(BBM), their disadvantages were pointed out. Then, the description and detailed flow were delivered. The advantages of GA were described as follows: first, there is no special request for search space and function dependence table (FDT); second, GA is a stochastic iterative method, so the initial value is unnecessary; third, GA searches from a group of solutions simultaneity, which improves the search speed and gets global optimal solution with higher accuracy. Finally, the gear reducer optimization problem was taking as an example and GA was used. The analyzing result was acceptable. The calculation quantity was reduced rapidly. The correctness and advantage of the GA were proved when compared the calculation quantity with the methods mentioned before.
Novel optimized implementation of CABAC hardware encoder
Wang Rui, Jiang Hongxu, Li Bo
2009, 35(6): 678-682.
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To improve the throughput of hardware architecture for CABAC(context-based adaptive binary arithmetic coder), the optimization methods based on dynamic properties of dataflow were adopted. By building the dataflow model of CABAC algorithm, four inevitable loops brought by hardware implementation were abstracted and isolated, and the potential bottle-neck loops were examined and optimized. For the context-loop, three assistant sub-loops with different iteration cycle were used to update the context variables needed by the data elements with different dependency-cycle. For the byte-package loop, a special kind of data elements was discriminated, which could simplify the circuit architecture and speed up the clock frequency. By building a dedicated fast by-pass channel for these special data elements, the throughput of byte-package loop was improved. Also benefiting from other basic optimization methods, the entire CABAC hardware architecture could achieve 309 MHz on FPGA(field-programmable gate array) platform and process one binary symbol per clock cycle.
Numerical simulation of dual shear coaxial gas-gas injector
Du Zhenggang, Gao Yushan, Li Mao, Cai Guobiao
2009, 35(6): 683-686.
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The turbulent Navier-Stokes equations in combination with the two equation k-ε turbulence model were used to simulate the flowfield in chambers of dual shear coaxial injector which the gaseous oxygen and hydrogen were used as propellants. The results of investigation display that: compared with traditional shear coaxial injector, the dual shear coaxial injector creates two shear combustion faces in chamber, and its outline varies a small amount. The ratio of center hydrogen mass flowrate to the total hydrogen mass flowrate is a key parameter for dual shear coaxial injector; at the ratio of 0.3, the advantage of two combustion surfaces is exerted completely. The dual shear coaxial injector could achieve a high combustion efficiency at the condition of large mass flowrate.
Lazy-substitution based symbolic execution for C programs
Lin Mengxiang, Chen Yinli, Chen Rui, Zhou Gang
2009, 35(6): 687-691.
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Lazy-substitution based symbolic execution was presented in order to address the computed memory location problem in traditional symbolic execution. A form of lazy strategy was introduced into traditional symbolic execution, which substitutes program variables with their symbolic values as much as possible. When the memory locations of variables in a statement can-t be determined statically or the length of a symbolic expression for substitution is too long, those variables won-t be replaced with their symbolic values. The lazy substitution algorithm was provided. Moreover, the lazy symbolic execution semantics for most of structures in C programming language were discussed in detail, especially for array and pointer. The prototype of symbolic execution system LazySEC (a lazy symbolic executor for C programs) performs lazy-substitution based symbolic execution for C programs. Preliminary experiment results show that LazySEC can handle program structures involving computed memory locations efficiently.
Icing simulation and evaluation of AEDC method
Chang Shinan, Hong Haihua, Zhang Yuzhu
2009, 35(6): 692-696.
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The arnold engineering development center (AEDC) icing scaling method was introduced and validated through numerical simulation. By icing modeling software, icing numerical simulations were performed for NACA0012 airfoil and its 1/2 and 1/3 scale models, cylinder and its 1/2 scale model. Flow field, droplets impingement and ice accretion computations were all included in the simulations. Scaling icing conditions were chosen according to AEDC method. The results show that the reference and scaling icing process have a wonderful similarity. It can be concluded that the AEDC method is effective and icing numerical simulation can be used in icing similarity research.
Modeling of active vibration isolation module with finite element method
Gao Yanlei, Li Lin
2009, 35(6): 697-700.
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Aiming at the design of the active micro-vibration control platform with large payloads at low frequency, one kind of the active vibration control platform using modularity design was proposed, which showed the characteristics of the strong carrying capacity and high isolation precision. Modularity simplifies the active vibration isolation platform design greatly. Using four modules the active vibration isolation platform can isolate the vibration of six degrees of freedom, by which a device of two tons can be isolated from vibrations. Because the module has the same construction form, the active vibration isolation platform-s characteristic is decided completely by the module-s characteristic. The finite element method was used to building the dynamic model of the active vibration isolation module, which contained the displacement vector for outside excitation and the force vector for actuator-s control force, when the above two vectors were zero, inherent characteristics of the active vibration isolation module were obtained by solving the dynamics model. Then validity of the dynamic model was illustrated by comparison with the results of the modal analysis by ANSYS software.
Fuzzy tuning Stribeck model and its application on flight motion simulator control
Fu Yongling, Niu Jianjun, Wang Yan
2009, 35(6): 701-704.
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New approach combined with friction lead compensation based on Stribeck equivalent control voltage model with its parameters fuzzy tuning and proportion integral differential(PID) control was presented to enhance the control traits of a middle axis driven by servo valve control hydraulic motor for a high precision flight motion simulator. Firstly, Stribeck equivalent control voltage parameters were directly acquired just with available components of simulator itself, thus avoiding model and parameters dependence of conventional feed forward friction compensation. Secondly, fuzzy-setting was designed to obtain the speeding relevant variables of the improved model to avoid the difficulty in ultra-low speed signals acquiring. Lastly, experiments were carried out to verify the merits of the approach. With a stable two-way minimum speed 0.000006(°)/s response represented by a triangle-wave, 95% time the tracking error is within 0.0002°, other servos such as sine tracking are also with high precision.
Reentry trajectory design of low lift-to-drag ( L/D ) ratio spacecraft based on predictor-corrector method
Li Huifeng, Ling Yuan
2009, 35(6): 705-708.
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To solve trajectory designing problem of the low lift-to-drag ( L/D ) ratio spacecraft when reentering into atmosphere with high speed, a predict guidance method was proposed, based on numerical predictor-corrector (NPC). The independent variable was changed to time instead of energy in order to avoid singularity. The 3-degree of freedom motion equations were established and longitudinal motion equations were inferential deduced. The value and sign of the bank angle were computed by longitudinal and lateral guidance separately while the main task of the latter was designing a lateral drogue deployment box. The results of simulation show that this method could educe appropriate reentry trajectory and bank angle according to the reentry conditions, and the velocity head, the rate of heat flow and g -loads are all suitable for the reentry desire.
Cost efficiency analysis of attack UCAV
Wei Jinzhong, Wang Guangyao, Gu Songfen
2009, 35(6): 709-713.
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The uninhabited combat aerial vehicle (UCAV) has its special characters of high stealth,high maneuverability, unmanned, and low life circle cost etc. Considering the features of the UCAV, and utilizing the method used in the modern aircraft cost efficiency analysis, the relationship between the main design factors, such as stealth, radius of action, maneuverability and weapon payloads, and the combat efficiency of attack UCAV was simulated. The effects of the main design factors on the life cycle cost of attack UCAV was calculated. The differences of cost efficiency among UCAVs, cruise missiles and manned aircrafts at the same threaten situation and at the same attack mission were studied. The UCAV-s position in the future war was analyzed. The study draws a conclusion that the cost efficiency of UCAVs is higher than that of manned aircrafts and cruise missiles in term of fulfilling suppression enemy air defenses mission.
Valence electron structure analysis of property differences between MoO2 and NiMo compounds
Lu Xiaofeng, Wang Huaming
2009, 35(6): 714-717.
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Valence electron structures of NiMo and MoO2 compounds in a MoO2-strengthened γ /NiMo alloy were analyzed by a bond length difference method on the basis of Yu’s Empirical electron theory of solids and molecules. Relationships between hardness, strength and melting point differences of the two compounds and their respective valence electron structure were investigated. The differences were confirmed by measurement results. The ratio of total covalent electron number to valence electron number on all of the bonds in valence electron structures could be used to compare strength of NiMo and MoO2. Length of the strongest bond in the valence electron structure could be used to measure melting point of NiMo and MoO2. However, covalent electron pair number of the strongest bond in the valence electron structure could not be viewed as the sole standard for comparing hardness of the two compounds.
Influence of chordwise bending stiffness on aeroelastic characteristics of flexible high-aspect-ratio wing
Leng Jiazhen, Xie Changchuan, Yang Chao
2009, 35(6): 718-722.
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High-aspect-ratio wing with low sweepback has been widely adopted by high-altitude long-endurance (HALE) aircrafts, and the wing boasts large deformation due to flight load. The coupling of stiffness between chordewise bending and torsion is intensified by the geometric nonlinearity, and chordwise bending mode plays key role in affecting the aeroelastic characteristics of the wing. Linearization of the structure was performed near its static equilibrium state under specific attack angle. Natural frequencies and mode shapes of the deformed wing were obtained, while the unsteady aerodynamics of the curved wing was calculated through strip theory. The flutter speed was determined by p-k method. Through the calculation of a metal beam wing, it can be concluded that there is a lower flutter speed with chordwise bending mode involved in coupling than without. Increase of chordwise bending stiffness is helpful for raising this flutter speed, and the effect of the torsional frequency should also be considered.
Application of software requirement error pattern based on ontology
Hu Xuan, Liu Bin, Wang Yichen, Jiang Chongwu
2009, 35(6): 723-727.
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The software error pattern concept was presented and the pattern orthogonal attributes, documentation and requirement error pattern production model were given. The domain-related requirement error pattern was described through ontology and the direct scenario of them primarily was analyzed. Direct scenario can help testers be familiar with usage in practice and actions and purposes of systems. It can also guide the process of inspection and test. The validity of inspection and test based on direct scenario of requirement error pattern were validated and the quality of development and test through orthogonal attributes of error pattern were analyzed.
Transfer alignment of strapdown inertial navigation systems on rolling bases
Wang Xinlong, Shen Liangliang, Ma Shan
2009, 35(6): 728-731.
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In the process of initial alignment for rolling bases, the accuracy of a model and the observability and observability degree of states are important facts to confirm the filtering effect. A fast and precise alignment method for rolling bases was discussed. Considering time-delay between the master and slave inertial navigation system, a precise transfer alignment model of "velocity + pose" matching was established. The observability analysis of piece-wise constant system (PWCS) and singular value decomposition of observability degree were combined, the observability degree of strapdown inertial navigation system (SINS) -s states were analyzed quantificationally, and the optimal estimation of SINS can be received at the three axes rolling state. Consequently, the SINS can achieve the optimal speed and precision of initial alignment performance. The choice of optimal maneuvers trajectory for carriers and the matching mode of transfer alignment can be gained for alignment of carrier weapons. The simulation results validate the efficiency of this method.
ElGamal type threshold digital signature scheme for Ad hoc networks
Hu Ronglei, Zhang Qishan, Liu Jianwei
2009, 35(6): 732-736.
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ElGamal type threshold signature is an important part of threshold signature. There exists a problem in the ElGamal type threshold signature proposed before that all signer must generate corporately a random number before threshold signature is executed. The computation and communication overhead of the scheme is heavy and not suitable for Ad hoc networks. An improved ElGamal type threshold signature scheme was proposed for Ad hoc networks. The composite public key (CPK) technology was used for generating random number. The scheme is composed of key initialization and threshold signature. All network nodes corporately generate a secret key and a random number matrix using distributed key generation protocol in the key initialization phase and every node hold secret key share and random number matrix share. When issuing part signature every signer select random number from its own random number matrix share using the same arithmetic. Then the part signature is used to reconstruct whole signature. The security of the scheme was proved in random oracle (RO) model. The practicability analysis shows that the computation complexity and the communication cost of the scheme are low, but the efficiency and success ratio are high.
Effect and mechanism of lift-enhancement of the co-flow jet technology
Liu Peiqing, Kuang Jianmin, Qu Qiulin
2009, 35(6): 737-740.
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The effect and mechanism of lift-enhancement of the co-flow jet technology was investigated by numerically simulating the flow around a co-flow jet airfoil. The Farve-averaged Navier-Stokes equation of unsteady compressible flow and the S-A turbulence model were solved by Fluent software. The results show that the co-flow jet technology remarkably reduces the zero-lift angle of attack of the airfoil, and increases the maximum lift coefficient and the stall angle of attack. The mechanism of lift-enhancement of the co-flow jet technology is analyzed theoretically. Firstly, it increases the circulation around the airfoil by accelerating the speed of the flow on its upper surface. Secondly, it decays the flow separation at the airfoil tail at high angles of attack through the injection of energy inside the boundary layer.
Accurate tool calibration for robotic conformance grinding system
Wang Wei, Yun Chao, Sun Kun, Wang Yuanyuan
2009, 35(6): 741-746.
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An experimental grinding tool calibration method was proposed to improve the accuracy of robotic belt grinding system. The accuracy of grinding tool-s horizontal axis calibrated by this new method is 0.05°. If the tool frame has a deflexion from the programmed pose, this deflexion is trigonometrically related to the depth difference in the grinded sample piece. After setting up the experiment system, the testing grinding experiments to magnify the deflexion were made. The experimental data on the grinded path were recorded and analyzed, after the sample piece was grinded completely by the contact wheel. The actual deflexion was obtained and the programmed tool pose was compensated to zero. To verify the accuracy and feasibility of this method, the sample piece was grinded with the compensated zero tool pose two times.
Design for repeater system with wideband and high sensitivity used in pilotless helicopter
Chang Xiaoming, Zhang Xiaolin, Bao Junhai, Liu Chunhui
2009, 35(6): 747-752.
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UAV (unmanned aircraft vehicle) is a popular platform of the world-s most advanced technology. A scheme was proposed that can be applied to the ultra short wave relay on the pilotless helicopter, and the system-s design, overall structure, working process of the system were explained, as well as the technical difficulties and resolutions met in practice. The most different character between normal relay system and the system this article described is the range of system frequency, the wideband of this system is no less than 200MHz. The signal from long distance can be capable of projecting with the relay, and the dynamic range is on less than 100dB. Weak signal can be detected and the sensitivity of the system is about -100dBm. When there is a powerful signal which is unexpected to receive, a mode called multi-narrow channels can be used to avoid the powerful signal. This system has been tested through a large quantity of experiments, and the statistics show that the relay is capable of projecting long distance signal, and is characteristic of wideband, high sensibility and powerful anti-jamming, and is a qualified system for the need.
Coverage control protocol using multi-intersection estimation for wireless sensor networks
Zhang Shuo, Liu Yuheng, Pu Juhua, Xiong Zhang
2009, 35(6): 753-757.
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In order to prolong the lifetime of wireless sensor networks(WSNs) while maintaining the required sensing coverage quality, a distributed control protocol which determines the redundant nodes in a necessary and sufficient condition was proposed. The protocol using MIER(multi-intersection estimation rule)dynamically controls the nodes to be working or sleeping in WSNs. It was theoretically proved that the MIER is a necessary and sufficient off-duty eligibility rule, which guarantees full coverage to target area and no blind point incurred while maintaining the number of on-duty nodes to a minimum. Simulation results demonstrate that, MIER was greatly improved than CCP rule, due to the elimination of blind points caused by protocol. It is better to utilize MIER rule for coverage control protocol, since it is a necessary and sufficient condition to judge redundant nodes, and more accurate to determine node into sleeping or not than some other rules. Coverage control protocol using MIER can be more efficient to reduce the network-s overall energy consumption and prolong the system lifetime than Ottawa protocol.
Characteristic analysis of the vortex in the flow past a circular cylinder
Dong Shuangling, Wu Songping
2009, 35(6): 758-761.
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In low-Reynolds-number flow past circular cylinder,the shape of vortices in the vortex street is not ideally axisymmetric,and changes with the the flow downstream. To solve the problem,finite element method was used to simulate the flow and the character of the vortex shape was analyzed by vorticity contour. Through analysis of a few contours,the vorticity contour changes due to the difference between the vorticity contour and the pressure contour. Generalized Joukowski transformation was used to describe the deformation of the vortex from axisymmetry.The result shows that three parameters describing the vortex change in respective ways,namely elllipticity varies parabolically, eccentricity varies linealy and bending angle is nearly constant. Kinematic expressions corresponding the three parameters were brought forward,comparison of the two expressions is satisfactory.
Cross-layer approach to allow MIMO-SDMA in WLAN
Chen Shengbo, Chen Wei, Liu Xuming
2009, 35(6): 762-765.
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Multiple input multiple output (MIMO), as an important technology to enhance the physical layer capability, can achieve this target via spatial reuse. An medium access control(MAC) protocol was proposed for uplink transmissions in WLAN, where both stations and access point(AP) were equipped with multiple antennas. This protocol solves those problems existing in utilizing MIMO under current 802.11 protocol, for example, how to deploy preamble (training sequence) used for channel estimation and how to enable simultaneous data transmissions via a cross-layer approach. Furthermore, a 3-dimension discrete-time Markov model was developed to analyze the performance of the proposed WLAN scheme. The analytical results were verified by the simulations, and numerical results show that system throughput can be significantly improved by the proposed scheme compared to conventional schemes.
Comparative studies of interior ballistic performance among several missile eject power systems
Rui Shouzhen, Xing Yuming
2009, 35(6): 766-770.
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Characteristics of several missile eject power systems were introduced and compared. The interior ballistic models of these power systems were designed on the basis of assumed conditions. And the programs were work out to predict and compare the interior ballistic performance about a certain missile and targets. The results of different power systems show the state parameters rules of working fluid with respect to the time in launching canister and the missile acceleration, velocity and displacement changing rules. The performance curves were compared and analyzed, which indicate that the working fluid flux of gas-steam eject power system is smaller, its structure is simpler and the pressure and acceleration change smoothly, the temperature is moderate, the missile velocity and displacement increase quickly, the launching time is shorter. Its interior ballistic parameters are better than others and have a great developing prospect. These results can provide a reference to design and select project of missile eject power systems.
Business end programming approach based on Bayesian network
Xing Shaomin, Zhou Bosheng, Chen Tianying
2009, 35(6): 771-774.
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Existing business end programming methods lack guidance for end-users without development experience. So a business end programming approach based on Bayesian network was proposed. First, a basic framework based on Bayesian network for end-users programming was presented. Then the domain expert system which is used to support the business end programming approach was established based on Bayesian structure learning method and process logs. On this basis, a heuristic method for business end programming taking domain expert system as core component was proposed. This method could recommend business activities to end-users in the process of programming relying on domain expert systems. It also provided real-time guidance and help end-users to complete programming step by step. Finally, the efficiency of the method was evaluated and analyzed, and the results show that the business end programming method based on Bayesian network could improve the efficiency of end-users programming to a certain extent.
ESSPI non-destructive testing of honeycomb sandwich panel for bonding defects
Luan Xu, Liang Jun, Cheng Jin, Wang Chao
2009, 35(6): 775-778.
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Bonding defects of the honeycomb sandwich panel reduced its strength greatly, thus the application in aeronautics and astronavigation was influenced seriously. The basic principles of electronic speckle shearing pattern interferometry (ESSPI) were introduced. Using ESSPI technique and thermal loading method, non-destructive testing to honeycomb sandwich panels was conducted, then image processing was carried through compiled program. The validity and practicability of ESSPI technique was proved through the three-point bending experiment. The results show that the main reason of strength decrease is the defects of facesheet and honeycomb core debonding, and the ESSPI is very effective evaluation technique to the honeycomb sandwich panel quality.
Effect of different clapboards structure in turbine blade trailing edge complex passages on flow characteristics
Ding Shuiting, Li Guo, Li Li, Wang Yong
2009, 35(6): 779-782.
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The experiment mainly conducted the effect of two different structure diaphragm plates in the complex passages on heat transfer of turbine blade trailing edge. A laser bean irradiated the passages and a low-motion vidicon screened the particle-s flow in second pass passage. Comparison the flow was made among two kinds of diaphragm plates: rectangular diaphragm plates(RDP), 120° waved diaphragm plates(WDP) in the complex passages of turbine blade trailing edge. It was found that both these two diaphragm plates influence the flow, and the WDP has a special oscillation pulsating flow effect in the second passage. For WDP, the Re has fierceness influence. The oscillation effects enhance along with the Re change.

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