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2012 Vol. 38, No. 3

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Rapid cockpit configuration design method research
Feng Haocheng, Luo Mingqiang, Liu Hu, Wu Zhe
2012, (3): 285-290,296.
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In order to improve the efficiency of civil airplane design in conceptual design phase, the design method of civil airplane-s cockpit was studied. The functionality was achieved in an open aircraft conceptual/preliminary design system. The coordinate of fuselage was defined. The method of defining eye design position of cockpit was studied. The method of cockpit layout and the parametric design and modeling method of windshield was presented. Based on these methods an interactive rapid design environment of civil airplane-s cockpit was constructed. Automatic adjustment for the cockpit was implemented, which was the basis for multidisciplinary design optimization in conceptual design phase.A design instance is given to illustrate the effectiveness of the methods.
Resource allocation scheme under rain fading in multi-beam mobile satellite systems
Yu Jia, Zong Peng
2012, (3): 291-296.
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An efficient dynamic resource calculation algorithm applicable to satellite networks was presented. The rain attenuation was taken into account, and adaptive forward error correction(FEC) coding technology was used to mitigate the decrease in signal to noise ratio caused by rain. In order to guarantee the information date rate and bit error rate, the proposed scheme adaptively increases the number of channels to transmit more information date.The algorithm-s performance was validated through simulation of different rain rates and frequencies, and the theoretical analysis and simulation results were matched perfectly.
Extended three-step focusing algorithm for spaceborne sliding spotlight SAR image formation
Yang Wei, Li Chunsheng, Chen Jie, Wang Pengbo
2012, (3): 297-302.
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Aimed at spaceborne sliding spotlight synthetic aperture radar(SAR) imaging mode, the hybrid factor was analyzed and amended along the range direction combined the geometry model firstly. Based on the analysis, the Doppler bandwidth of both single target and whole scene were researched, and the validity of the two-step approach to overcome azimuth spectrum aliasing was proved by mathematic derivation. Moreover, the limitation of two-step approach was illuminated by thorough research. Namely, the azimuth overlapping will appear in image domain without high pulse repetition frequency. A extended three-step focusing algorithm was presented to resolve the disadvantage of two-step approach. After azimuth data focusing, a deramp operation was adopted to finish the resample in azimuth with a selected deramp factor, by which the azimuth overlapping in image domain was overcome. And, the azimuth time extension caused by deramp operation was also researched. Finally, the simulation results justify the superiority of the extended three-step algorithm.
Design and analysis of interception project for multiple kill vehicle interceptor
Xie Yu, Liu Luhua, Tang Guojian, Cui Junfeng
2012, (3): 303-308.
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The multiple kill vehicle (MKV) interceptor consists of a carrier vehicle and some small kill vehicles that can intercept targets independently. It is capable of solving the difficulties of traditional kinetic energy interceptor, such as multiple targets identification and interception. The interception project of MKV interceptor was designed based on midcourse interception for multiple warheads of long-range ballistic missile, and the MKV-target engagement process was analyzed. Furtherly, some key issues such as MKV guidance strategy, MKV release strategy, influence of maneuverability on interception, and targets assignment strategy were studied. The simulations demonstrate that the designed interception project is adaptable of multiple warheads interception for a long-range ballistic missile.
Secondary flow thrust vector control study for fluidic throat nozzle
Zhang Jianhua, Xie Kan
2012, (3): 309-313,318.
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The secondary flow vector control concept for the fluidic throat nozzle of solid rocket motor was studied. Through numerical simulation, the work condition of concurrent thrust modulation and vector control was analyzed, in which there exist secondary flow at the throat and expansion part meanwhile. The throat modulation and thrust vector control performance of nine typical secondary flow concepts were compared, and the influence on the secondary flow vector control was discussed for the existence of secondary flow at the throat. The results of concept comparison can provide references for practical design.
Design of adaptive flight control system for aircraft with center of gravity variations
Zhang Jing, Shen Gongzhang, Yang Lingyu
2012, (3): 314-318.
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Due to the center of gravity varying over a specific range, the aircraft may deviate from its known dynamics, thus bringing special problems to the attitude control system. To overcome the limitation of accurate mathematical model and poor robust performance of conventional methods, a new design approach of adaptive flight control system for aircraft with center of gravity variations was proposed. The base control law was designed based on inverse dynamics and center of gravity estimation. Then the adaptive sliding mode control module was introduced, in which the sliding mode control could guarantee the robustness and stability of closed loop system, and the adaptive module was designed to compensate model uncertainties and estimation error. The stability of closed loop was proved using Lyapunov stability theory. Simulation results demonstrate that the proposed method compensates uncertainties effectively, and its robust performance is also excellent.
High-accuracy quick-reaching sliding mode variable structure terminal guidance law
Song Yuanyun, Chen Wanchun
2012, (3): 319-323.
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A variable structure terminal guidance law with adaptive quick-reaching law and a filter approach based on sliding mode observer was developed for short time interception. During the ideal and non-ideal condition with typical target maneuvers, the simulation results demonstrates the higher accuracy, better robustness and easy realized of the designed guidance law by comparing with the conventional proportional navigation, augmented proportional navigation and switched bias proportional navigation. Also the filter approach is shown to be more effective than the extended Kalman filter (EKF) for the colored noise.
Signal scaling strategies for motion-base spaceflight simulators
Chen Wei, Jiang Guohua, Chao Jiangang
2012, (3): 324-329.
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When input signal is scaled in a large scope, the third-degree polynomial scaling is easy to induce signal distortion and complicated for parameters tuning, and the trigger speed of Hermite scaling is too slow to satisfy the condition. Based on this situation, two methods were put forward: the scaling of optimal parameter configuration based on the third-degree polynomial scaling and the non-linear scaling combined with linear scaling. The first method maximizes the stable region to prevent signal distortion by optimizing the configuration parameters; the latter one restricts the scaling scope in the stable region by utilizing the characteristics of linear scaling. The results have indicated that signal distortion can be avoided when the linear scaling joins in the third-degree polynomial scaling, and the method based on optimal parameter configuration shows advantages in parameters tuning and integrated scaling performance. The two methods provide more effective scaling strategies for spaceflight simulation.
Numerical simulation of ice accretion on helicopter rotor
Zhong Guo, Cao Yihua, Zhao Ming
2012, (3): 330-334,339.
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In order to study the prediction of ice accretion on helicopter rotor, a theoretical rotor icing model was founded based on the computational fluid dynamics (CFD) technique by analyzing the theory of ice accretion and helicopter flight. Euler two-phase flow theory was used in solving the governing equations corresponding to droplets, and a modified model of the mass and heat transfer on ice surface was proposed based on the classical Messinger model. The method of prediction of ice shape on rotor was analyzed detailedly by using UH-60 and CH-47 as examples, and they can lay the foundation of the research about the helicopter dynamics in the icing condition and the design of anti/de-ice system. The result shows that the method has positive significance of improving the flight safety performance of helicopter.
Analysis and correction on relativistic effect of inter-satellites using dual one-way ranging/time synchronization
Sun Wenchao, Chang Qing, Xu Yong, Qi Wei
2012, (3): 335-339.
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The calculation of dual one-way ranging/time synchronization (DOWRT) between dynamic satellites was analyzed. In addition, relativistic effect on ranging/time synchronization was presented. A calculation with relativistic correction of DOWRT was proposed. Measurement errors of ranging/time synchronization in low earth orbit(LEO) formation constellation and in navigation constellation caused by relativistic effect were simulated and comparatively analyzed. Simulation results demonstrate that when inter-satellite DOWRT method is adopted, ranging measurement and time synchronization errors during LEO formation flying caused by relativistic effects are in meter-scale and sub-picosecond level respectively, while in navigation constellation measurement, the corresponding errors would be in hundred-meter scale and microsecond level. As a result, relativistic correction should be included in order to realize high-precision ranging and time synchronization measurement between navigation satellites.
Modified-PCNN based detection of gyroscope pivot surface defects
Zhao Huijie, Ge Wenqian, Li Xudong
2012, (3): 340-344.
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Pulse coupled neural networks (PCNN) differs from traditional neural networks. PCNN can be applied to image processing without training. There are many structure parameters in PCNN model, and it is difficult to determine these parameters by manually trying. The model structure was improved by simplifying feedback input and connection input, and thus the number of the parameters was reduced. The inside connection coefficient was calculated dynamically based on neighborhood grayscale. The weight matrix was obtained by utilizing neighborhood Euclidean distance. The dynamic threshold was calculated from image grayscale character. The modified PCNN was used to segment several gyroscope pivot surface defects images. Based on the buffer region matching method, the completeness and correctness measures were used to compare the presented method, maximum entropy and Canny segmentation, and the results showed the two measures were not less than 0.9, which means that the proposed method is more effective.
Error propagating characteristic analyzing for rotating LG INS
Yin Hongliang, Yang Gongliu, Song Ningfang, Wang Lifen
2012, (3): 345-350.
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Understanding the mechanism of rotation modulation error auto-compensation and grasping the characteristic of front-to-back error propagating are the utmost important jobs for the design of a rotating inertial navigation system (INS). Basing on these, a reasonable rotation scheme can be designed and verified by simulating and testing at the time. Combining with the working principle and error propagating equation of single-axis rotating INS, the mechanism of rotation modulation error auto-compensation was explained. By theory reasoning and mathematically simulating, inertial sensors- error propagating characteristics of constant errors, rand errors, scale errors and mount-errors were analyzed, and the effects of error modulation by using single-axis rotating INS for inertial sensors were obtained. All these results show that this rotation scheme is effective and feasible for INS. The studying results can offer both theory reference and design basis for the realization of the rotating laser gyroscope (LG) INS.
Mechanism parameters optimization of bionic frog jumping robot based on velocity directional manipulability measure
Hu Shenghai, Yang Qi, He Lei, Tan Xiangquan
2012, (3): 351-356.
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The improvement of jumping performance of bionic frog jumping robot was pursued in view of the mechanism design, taking velocity directional measure as an evaluating index of jumping performance. On the basis of bionic frog jumping robot mechanism model, kinematic equations in takeoff phase were established, and the velocity mapping relation of robot from the joint space to the moving space of the center of mass was obtained. Optimal algorithm combined with velocity directional measure was used to optimize the mechanism parameters of the bionic frog jumping robot, in order to optimize the jumping performance of the robot. The optimal result shows that the research on mechanism parameters optimization of jumping robot is feasible by using the theory of velocity directional measure.
Effect of gas species on fire extinguishment using two phase flow
Yang Lijun, Zhao Jianbo, Liu Yuxin
2012, (3): 357-362.
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In the fire extinguishment system by using two phase flow, when the gas phase uses different gas species, the fire fighting effects are different. Four gases were used as the gas phases like air, nitrogen, carbon dioxide and argon. The experiments were conducted in a room measured by 3.6 m 4.6 m 3.9 m and the fire sizes were 0.1 MW and 0.61 MW. The type K thermal-couple tree and Siemens oxygen analyzer Oxymat-61 were used to measure the fire temperature and oxygen concentration separately. The fire extinguishment characters using two phase flow water mist under different gas phase conditions were got. The mode of actions under different gas species on fire extinguishment was concluded and the reason that the difference takes place was analyzed. Compared with the single phase flow, it shows that the fire extinguishment efficiency by using two phase flow under low system pressure is equal to single phase flow under higher system pressure.
Adipic-sulfuric acid anodizing for LY12CZ aluminum alloy
Yu Mei, Chen Gaohong, Liu Jianhua, Li Songmei
2012, (3): 363-367,379.
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Adipic-sulfuric acid anodic oxidation was improved by adding hexane diacid into sulfur acid anodic bath solutions for LY12CZ aluminum alloy, and compared to conventional sulfur acid anodic oxidation. The morphology of two kinds of oxide films was observed by using filed emission-scanning electron microscope (FE-SEM). The corrosion resistance and electrochemical character of oxide film were investigated with electrochemical impedance spectroscope (EIS). Tensile fatigue test of anodic LY12CZ plates was carried out. It is found that adipic-sulfuric acid oxide film has smaller pore structure and fewer defects, and it has better stability and corrosion resistance in corrosive environment. The influence of anodic oxidation on the fatigue properties decreases. The mechanism of adipic-sulfuric acid anodic oxidation was also discussed.
Framework for multi-resolution modeling based on BOM and FEDEP
Li Yuan, Li Bohu, Hu Xiaofeng, Chai Xudong
2012, (3): 368-373.
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To normalize and generalize representing multi-resolution models (MRMs) and the process as well as the activities in multi-resolution modeling (MRM), a framework for MRM based on base object model (BOM) and federation development and execution process (FEDEP) was put forward. The framework is comprised of three MRM approaches based on BOM and a MRM process based on FEDEP. The three methods were introduced briefly. By setting forth those fundamental activities in FEDEP concerned with BOM and MRM in detail, the process of BOM based MRM was integrated into the FEDEP. The framework can formalize the representations for MRMs and normalize the activities and process for MRM. This facilitates the reuse, interoperability and composability for MRMs and consistencies among them, which asserts the effectiveness for MRM.
Dressing process and parametric optimization of cup-shaped vitrified CBN wheels
Liu Jia, Chen Wuyi
2012, (3): 374-379.
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Influences of dressing parameters on grinding temperatures, grinding forces and surface roughness in grinding TC 4 with cup-shaped CBN wheels dressed with a diamond roller under dry condition were investigated through experiments. Grinding temperatures and surface roughness were analyzed adopting regression method. Based on the mathematical models obtained by regression, weighted double-objective optimization was performed for lower grinding temperature and lower surface roughness. Finally, the optimal dressing parameters were calculated respectively for rough grinding and finish grinding and verified through grinding TC 4 experiments.
New automatic regulation system of electron beam welder cathode heating source
Xu Guoning, Qi Bojin, Liu Fangjun, Dai Hailin
2012, (3): 380-383.
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One new electron beam welder cathode heating current automatic control system was developed, which includes new main circuit topology and corresponding control strategy, and it can make cathode be optimal heating current status and improve electron beam stability. At the same time, cathode heating current can be turned off automatically when no high voltage, and cathode heating current can be reduced automatically when electron beam current import is zero, thus it can increase cathode life time. The test proves that this system operates simply, rapidly and exactly, and it can make good welding seam comparing with traditional cathode heating source.
Simulation of progressive damage on composite structure under hydro/thermo/mechanical coupled condition
Liu Yujia, Yan Ying, He Mingze, Qi Zhongxin
2012, (3): 384-388,393.
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A tracking method of progressive damage on composite structure under the hydro/thermo/mechanical coupled condition was developed. The finite element model was built considering the random distribution of mechanical properties. Constitutive relation of composite material under hygrothermal condition was improved. Taking Hashin criteria and maximum stress criteria as failure criterion, the whole damage process from initial damage to ultimate failure of composite open hole laminates was simulated completely by this method under different hygrothermal conditions and different load types. The errors between ultimate strength prediction results and experimental results are less than 10%, so the effectiveness of this method is verified. The hygrothermal effect on the damage initiation and evolution shows that initial damage appears earlier and the ultimate strength and ultimate strain decreases under hygrothermal condition compared with room temperature dry condition.
Mode shape functions of free paraboloidal thin shells
Wang Xinjie, Yue Honghao, Deng Zongquan
2012, (3): 389-393.
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Based on the membrane theory, a set of mode shape functions for paraboloidal thin shell with free boundary condition were formulated. Low mode shapes of free paraboloidal thin shell were obtained by the way of modal experiment analysis. The theoretical mode shapes based on the mode shape functions were compared with the mode shapes through finite element method and experimental method. The results show that the theoretical mode shapes agree well with the mode shapes through finite element method and experimental method. Then mode shapes of paraboloidal thin shell can be correctly described by the mode shape functions.
Low complexity improved SLM algorithm for PAPR reduction in PLC system
Chen Ke, Hu Xiaoguang
2012, (3): 394-399.
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A reduce peak-to-average power ratio (PAPR) algorithm was proposed aim at the slow-variant and complex noise of channel. The partial data within the original data sequence were scrambled by circularly shifting to obtain a set of new data sequences. Each new data sequence tail was inserted the corresponding side information (SI) to form the input candidate sequence. Inverse fast Fourier transform (IFFT) was operated by different input candidate sequence separately to obtain different output sequence. Chosen of the lowest PAPR, the PAPR of system could be greatly reduced. The simulation results indicate that the improved algorithm can reduce PAPR effectively and get a better bit error rate and the algorithm has lower computational complexity than selected mapping (SLM).
Open-loop memory polynomial pre-distorter based on look-up table
Yang Youfu, Zhang Qishan, Liu Jianwei, Xiu Chundi
2012, (3): 400-404.
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An open-loop memory polynomial pre-distorter based on look-up table was proposed. Both memory polynomial model(MPM) pre-distorter coefficient estimates and the implementation of signal pre-distortion processing were considered. First, with the complementarity on the transmission characteristics for pre-distorter and high power amplifier(HPA), the memory polynomial coefficient was extracted by using once least squares algorithm using sampling input and output signal of power amplifier. Therefore our scheme eliminates convergence issue and reduce calculated amount in iterative architecture which emerged in traditional pre-distorters. And then, by analyzing the feature of memory polynomial pre-distorter, one-dimensional vector table look-up was established, which based on look-up the index of amplitude of input signal. With power-accumulate operations in MPM pre-distorter was implemented through the look-up table, dramatically reduce the cost of computing and hardware for implementing pre-distorter. The simulation results show that, the proposed pre-distorter can effectively compensate memory nonlinearity distortion of system due to high-power amplifier, and the power spectrum characteristics improves approximately 20 dB in the valid bandwidth. Therefore, our scheme can dramatically improve the system bit error rate performance.
Analysis on energy-saving operation of screw compressor under load/unload operating conditions
Kong Dewen, Lin Weiqin, Cai Maolin, Qin Hongbo
2012, (3): 405-409.
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Air compressor power consumption was described. Based on analyzing screw air compressor volume flow efficiency under discharge pressure fluctuation conditions, the screw air compressor volume flow formula was obtained, and power consumption mathematic model were established also. Under load/unload operating conditions, to change the unload pressure value in accordance with the space step of 0.01MPa and consider the power consumption affected by current from unload to load, the screw compressor power consumption were simulated by MATLAB. The simulation shows that the existence of the optimal unload pressure value is proved. Power consumption is minimal with using the optimal unload pressure value. Finally, combining the load/unload operating frequency with the optimal unload pressure value, the optimal control method of screw compressor is given.
Modeling and simulating of planar multi-body systems with rolling resistance and Coulomb friction
Cao Jie, L? Jing, Wang Qi
2012, (3): 410-415.
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To study the planar multi-body systems with rolling resistance and Coulomb friction, the generalized mechanics model with a number of rigid bodies and disks was established and the dynamical equations of the system were derived from Lagrange-s equations of the first kind in Cartesian coordinate. In order to compute constraint forces, constraint equations of the system were expressed by local approach and the generalized forces of rolling resistance couples and Coulomb friction forces were given in the matrix notation. The complementarity conditions of the rolling resistance law and the reaction forces of the hinge were formed to solve the non-smooth differential equations. A constraint-stabilized event-driven method for the system was given. So the problems of the computation for non-smooth forces and the reaction forces of the hinge and the judgment for the stick-slip were transformed into a linear complementarity problem. The disk and the planar rigid multi-body system with rolling resistance and Coulomb friction were respectively considered as demonstrative application examples and numerical results were presented.
Automatic dimensioning of 3D model based on GB/T 24734
An Heng, Yan Guangrong, Lei Yi
2012, (3): 416-421.
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To meet the requirements of manufacturing enterprises, the automatic dimensioning of 3D model in CAD system was investigated based on the national standard GB/T 24734. The algorithms of automatic dimensioning of 3D model were proposed, and the strategies of datum recognition, features simplification, surfaces grouping, vertical projection and features restoration were described in detail. Currently, the processes of features simplification and restoration mainly deal with the blending, chamfering and array operations in both feature and cross-section levels. To make the layout and identification of dimensions much easier, the methods of surface grouping and vertical projection were applied to discompose the part. All the algorithms presented were realized and a module of automatic dimensioning was developed based on CAXA Solid. Case study shows that the strategies presented are feasible.
Composite damage analysis subjected to low-velocity impact
Liu Debo, Guan Zhidong, Chen Jianhua, Li Zengshan
2012, (3): 422-426.
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A new type of zero-thickness cohesive element model was proposed to study the composite interlaminar damage. The delamination propagation of laminates subjected to low-velocity impact can be prediceted accurately by the model. The model consisted of constitutive relationship, damage criterion and damage evolvement. The model was implemented with the commercial finite element software ABAQUS using the user subroutine VUEL. 3D solid element was used in plies and 3D Hashin damage criterion was used with VUSDFLD to predict the fiber and resin damage. Finally, the model was used to predict the progress of delamination in the impact test and compression after impact (CAI) test of domestic carbon fiber/resin composite (CCF300/5428). The result shows that this cohesive element is effective to detect delamination during impact and CAI.

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