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2013 Vol. 39, No. 10

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Modeling and analysis of multi-helicopter coordinate system with slung load
Song Yanguo, Wang Huanjin
2013, 39(10): 1279-1285.
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A generic simulation model of multi-helicopter cooperated system with slung load by using elastic cable has been developed for research on control and avionic instrumentation. Flight dynamic models of each helicopter and payload were developed respectively. Elastic cables were treated as spring/damping systems, and the dynamics of each helicopter and slung loads was tightly coupled by elastic cables'dynamics. Simulation model of helicopter system with slung load was built, and analysis of stability and trim were conducted. The results indicate that slung load obviously affects each helicopter's dynamics properties based on qualitative analysis, and the modeling method is validated and feasible for multi-helicopter system with slung load.
Design of a novel curved wall profile multi-step feed horn
Zhang Yongfang, Miao Jungang, Jiang Jingshan
2013, 39(10): 1286-1291.
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A novel multi-step feed horn with a curved inner wall was introduced. The curve profile of its inner wall is composed of the sine profile and the Gaussian profile. This feed horn can be easily manufactured due to its simplified structure, and its radiation performance can be improved by optimizing the inner wall curve profile. A multi-step horn with an optimized inner wall curve profile was designed in the spectrum between 75 GHz and 110 GHz. The optimized feed horn has excellent electrical performance and beam symmetry characteristics, with voltage standing wave ratio (VSWR) less than 1.1 at the established waveband, a bandwidth ratio of about 1.5:1. In addition, the measured radiation pattern of the designed feed horn is in good consistency with calculation results.
Design and optimization of elimination tool in rubber forming of TB5 titanium
Sun Yongna, Wan Min, Wu Xiangdong
2013, 39(10): 1292-1297.
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Wrinkling will occur in the rubber forming of convex flange, even for the forming of TB5 titanium when the flange height is higher. Wrinkling was quantified as objective functions. The rubber forming process with different side blank holder parameters were simulated based on the optimum design and FEM. Influences of different side blank holder parameters on the wrinkling were analyzed. The relationship with forming index was approximately expressed as a polynomial function. Optimal parameters were obtained using proper optimization methods based on the response surface methodology and quasi-Newton method. Practicability and validity of the optimization methods proposed in this work were verified by experiments.
Fatigue crack monitoring of metallic structure based on coating sensor
Hou Bo, He Yuting, Cui Ronghong, Ding Hua
2013, 39(10): 1298-1302.
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To allow continuous crack monitoring of aircraft metallic structures during their service, a fatigue crack monitoring method was presented based on modern surface technology and electrical potential technique. A crack monitoring coating sensor, consisting of the insulated separating layer, the conductive sensing layer and the packaging protective layer, was deposited on the hot spots of the structure. Fatigue crack monitoring experiments were carried out. Experimental results show that the information about crack can be acquired through analyzing the changes of the resistance (electrical potential) values of the surface coating sensor and the crack on different spots of aluminum alloy joint structures can be monitored availably at the same time. Moreover, the fatigue property of the specimen with surface coating sensor and that of the original specimen were studied. Contrast experiment results show that there is no obvious influence on the fatigue property of the 2A12-T4 aluminum alloy to prepare the coating sensor on its surface by modern surface technology.
Analysis of the effect of ventilation positions on hydrodynamic characteristics of submarine-launched vehicle
Sun Tiezhi, Wei Yingjie, Wang Cong, Cao Wei
2013, 39(10): 1303-1308.
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Based on the theory of homogeneous equilibrium flow, by solving the RANS equations of mixture media, SST turbulence transport equations and the mass transport equations between each phase, three dimensional numerical simulation was carried out to study how the positions of ventilation holes impact on the submarine-launched vehicle's hydrodynamic characteristics. The characteristics of the cavity shape, the surface pressure distribution and the drag force change under different ventilation positions were compared. The result shows that the cavity shape is fracturing with the space between two ventilation orifices reaches to a certain value; The surface pressures of the face flow surface and the back flow surface will both increase at the region, and also a pressure peak value will occur at the closing position of cavity; The pressure drag coefficient and the viscosity drag coefficient decreasing gradually show a deceasing trend with the space between two ventilation orifices increasing under the same quantity condition of ventilation.
Modeling air combat situation assessment based on combat area division
Xiao Liang, Huang Jun, Xu Zhongshu
2013, 39(10): 1309-1313.
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The beyond visual range(BVR) air combat has become one of the most important air modes of modern air combat. The whole airspace division was made base on advantages and disadvantages of regional area. Four specific airspace situations were put forward. A new model was set up combined situation assessment model and formation combat capacity model. Using principal component analysis(PCA)to select input variables of formation combat capacity model, which can reduce the complexity of collecting data. Combined neural network was used for effectiveness evaluation of BVR. Combine genetic algorithms(GA)with back propagation(BP) neural network,using GA's global to search optimized BP network structure parameters,overcome the local convergence and other issues of BP algorithm effectively. The result shows that the model can limit the artificial factors, making the solution more objective and creditable.
Simulation of the working process of launch vehicle pressurization system in random vibration condition
Wang Chong, Liang Guozhu
2013, 39(10): 1314-1318.
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To study the dynamic characteristic and stability of the launch vehicle tank pressurization system working in random vibration condition, harmony superposition method was used to simulate the random process; and component-shell-placement was introduced as vibration excitation to modify the existing model. The gas pipes and components were respectively modeled using the one-dimensional flow equations under the Lagrange reference frame and the ordinary differential equations, working processes of the pressurization system in/without the vibration condition were simulated. In the vibration condition, pressure fluctuation was observed, which may lead to the oscillation of the regulator, and destroy the stability of the component. The vibration presents little conspicuous influence with the ullage pressure during the full course of work. The data of the system working in non-vibration condition was compared to the given test record, a satisfying agreement was reported. The mathematical model and calculating method are validated to be effective in the calculation of the working process of the launch vehicle tank pressurization system.
Gradual fault prediction method for electronic system based on adaptive RVM
Fan Geng, Ma Dengwu, Zhang Jijun, Wu Minghui
2013, 39(10): 1319-1324.
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Aiming at gradual fault prediction of electronic system, a method based on adaptive relevance vector machine (RVM) was proposed. Firstly, the phase space of electronic system performance parameter time series was reconstructed, and then the corresponding relationship between the input and the output of RVM was educed. Secondly, the artificial fish swarm algorithm (AFSA) was adopted to realize the adaptive optimization of method parameters, which took the embedding dimension and the RVM kernel parameter as the artificial fish position and took the opposite number of leave-one-out cross-validation (LOOCV) error as the objective function. Lastly, the performance of the proposed method was validated by radar transmitter fault prediction experiment. The experimental results show that the proposed method has better accuracy and reliability than the existed methods.
Anchoring point and blow-off mechanism of Bunsen laminar premixed flame
Huang Xia, Huang Yong, Gong Fan
2013, 39(10): 1325-1330.
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A velocity-matching method (VM Method) combined with the wall quenching effect was used to analyze the anchoring point movements and the blow-off characteristics of a methane-air laminar premixed Bunsen flame in lean and rich conditions. A blow-off model was achieved and proved by experiments. The flame was anchored in the shearing layer near the burner exit, where the local velocity was equilibrium with the flame speed; there was also an ignition area in the boundary layer. This ignition area was diminished when the flow velocity increased or the equivalence ratio was away from the stoichiometric ratio. When the ignition area became a point, the blow-off occurred. The anchoring point movements were predicted by comparing the local flow velocity and the flame speed, and considering the wall quenching effect in a decoupled method. With the increasing incoming velocity, in radial direction the anchoring point moves towards the jet center line, and in flow direction it moves downstream in fuel-lean conditions and upstream in fuel-rich conditions, respectively. This movement and the ignition area analysis predict the blow-off characteristics, and are validated by experiments. The result shows a good precision and proves the blow-off mechanism.
Energy efficiency state evaluation method for ammonia refrigeration system
Liu Chong, Cai Maolin
2013, 39(10): 1331-1336.
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In order to evaluate the energy efficiency of the ammonia refrigeration system, a novel two-dimensional matrix model was proposed. Based on thorough analysis of the popular evaluation methods, analytic hierarchy process-fuzzy comprehensive evaluation and information entropy method, a new combination weight evaluation method was put forward with the least squire. What's more, for better performance comparison, necessary actual cases were conducted and it proved that the new method has better precision, higher linearity and greater consistence with actual energy efficiency. Also, the energy efficiency state can be assessed instantly with this method and by adjusting necessary parameters the system can operate more optimally with less energy consumption.
All-lifting-vehicle induced flow improvement effect
Wang Linlin, Gao Ge
2013, 39(10): 1337-1341.
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The saucer-shaped aircraft is a kind of all-lifting-vehicle with low aspect ratio. Bionic fin-shaped wing tips were used to improve the induced flow over the saucer-shaped aircraft and impair the induced flow separation, and then the aircraft aerodynamic efficiency could be increased. The high precision wind tunnel tests were conducted to investigate the induced flow improvement effect of the saucer-shaped lifting body, with the adopting of the fin-shaped wing tips. Numerical simulations basic on the high precision wind tunnel tests were also used. The results show that the fin-shaped wing tips could highly improve the induced flow over the saucer-shaped aircraft.
SPM based on normalized cut for image classification
Ding Kai, Chen Weihai, Wu Xingming, Liu Zhong
2013, 39(10): 1342-1347.
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It is difficult to classify scene images with high accuracy when the dataset is relatively large. Spatial pyramid matching was proposed to deal with this problem, but there are some shortages. As an improvement, the algorithm based on normalized cut was proposed. Normalized cut was utilized instead of K-means for clustering. The size of codebook was regulated referring to quantity and size of the images, by calculating sub-codebook for every category and re-clustering the codes. Distance between categories was enlarged by quantifying unknown features with Gaussian model and rescaling the histogram features. Experiments prove that new approach can get higher precision than the original by 4.6% at most.
Design and analysis of locust-like jumping mechanism
Yin Junmao, Chen Diansheng, Shen Qi
2013, 39(10): 1348-1353,1359.
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A jumping mechanism based on jump characteristics of locust was presented. By biological observation and kinematic analysis of locust jump, the key effect of locust's hind leg knee on the jump performance was discovered, and a simplified dynamic model of locust was built to simulate locust take-off. According to the simplified locust model and physiological structure of the locust's hind leg, a 1 DOF locust-based jumping mechanism was put forward. The kinematical analysis of the mechanism during take-off was implemented and the ground reaction force on hind leg of locust was compared with that of the locust jump simulation. The results show that the mechanism has the similar mechanical properties as locust. Finally, the prototype experiment verifies the analysis results. It provides a valued basis for further research of locust-like efficient flexible jumping mechanism.
Modeling and control simulation of PZT-DDV using hydraulic amplification
Yu Juntao, Jiao Zongxia, Wu Shuai
2013, 39(10): 1354-1359.
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A servo valve direct driven by piezoelectric actuator (PZT-DDV) using hydraulic amplification was researched. It takes advantage of the higher bandwidth and larger flow rate. The actuary model was built. The characteristic of PZT-DDV was investigated based on the co-simulation environment of AMESim and Simulink. By using AMESim the PZT-DDV nonlinear model and hydraulic environment have been set up. By using Simulink the digital controller model had been set up. LuGre friction model was used to estimate the friction force, feed forward and adaptive back stepping control was investigated to improve the hysteresis, friction and load sensitive characteristic of PZT-DDV. The simulation results demonstrate that the steady precision can be improved by the adaptive back stepping control and the dynamic performances can be improved by the feed forward control.
Rate-dependent modeling and tracking control of giant magnetostrictive actuators
Guo Yongxin, Mao Jianqin
2013, 39(10): 1360-1365.
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A Hammerstein model was proposed to model giant magnetostrictive actuators (GMA). A modified Prandtl-Ishlinskii(MPI) model and an autoregressive model with exogenous input (ARX) were used to represent the static nonlinear part and the linear dynamic part of the Hammerstein model respectively. Model identification method was also given. The proposed model can describe the rate-dependent hysteresis of GMA from 1 Hz to 100 Hz well. A compound controller containing inverse compensator and proportional-integral-derivative (PID) feedback was designed for tracking control. Real time trajectory tracking of single frequency and composite frequency sinusoidal reference inputs with the amplitude of 16 μm was conducted. The root-mean-square error was less than 1μm and the relative error was less than 10%, which verify the effectiveness of the control strategy.
Model parameters updating of lunar lander
Wu Jianyun, Wang Chunjie, Wang Han
2013, 39(10): 1366-1369,1375.
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The parametric model of the lander was established, and the landing collision process was simplified as a spring-damper model. Parameters including stiffness, damping, force exponent and the maximum penetration depth were set to be updated. Landing stability plane was defined to determine whether the lander was overturned. Based on the ground stability experimental results, ADAMS and Isight were used to make co-simulation, and optimized super Latin square method was adopted to narrow the range of the updated parameters. Based on the model updating theory, adaptive simulated annealing method was adopted to the model parameters updating. It is proven that the effect of collection is obvious and the updated simulation model conforms better to the actual experimental prototype.
Ionospheric delay in the Antarctic GPS positioning
Xu Yan, Yang Yuanxi, Xu Guochang, Jiang Nan
2013, 39(10): 1370-1375.
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Based on the global position system(GPS) dual-frequency measured data of international GNSS service (IGS) station in Antarctic region, the variation of ionospheric delay and the impact of ionospheric second-order delay on GPS positioning was analyzed. Result shows, total electron content(TEC) in Antarctic region has frequent fluctuation during the day and the maximum TEC in the daytime changes more intensely than in the mid-latitude area. In Antarctic region, the influence of ionospheric second-order delay on GPS positioning can achieve a magnitude of cm in summer. In case of the applied limitation of global ionosphere maps(GIM) provided by the European Center for orbit determination(CODE) in the polar area, six IGS stations in Antarctic region were chosen as base stations to establish the regional ionosphere model(RIM). Results show, in Antarctic region the positioning precision of RIM is more superior than GIM to some extent.
Fisher discriminant method for multiple compositional-data variables in simplex space
Shangguan Liying, Wang Huiwen
2013, 39(10): 1376-1380,1391.
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As foundation work, the algebra operations of compositional-data vector were investigated,based on the algorithms of compositional data in simplex space. Further, according to traditional method, Fisher discriminant analysis(FDA) on multiple compositional-data variables was proposed. The novel method built the linear discriminant function based on the operations of compositional-data vectors. And the discriminant rule on compositional-data variables was investigated with the theory of distance discriminant analysis. The sample can be classified according to the distances between the projective point of a sample for discrimination and that of the cluster centers. Both simulation results and application analysis show the usefulness of the proposed methods. The algebra system of compositional-data vectors lays the foundation for extending the other multivariate statistical method to multiple compositional-data variables.
Original task planning method of early warning system of LEO based on DPSO-SA
Jian Ping, Zou Peng, Xiong Wei
2013, 39(10): 1381-1386.
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To improve the resource efficiency for missile tracking with early warning system of low-earth-orbit(LEO), the original task planning model of early warning system of LEO was set up. The model includes the optimizing indexes of tracking precision, task accomplishment and resource slack. The dynamic priority of meta tracking task was defined and designed in view of the information uncertainty of missile object in tracking. Based on the model, a mixed discrete particle swarm optimization (DPSO) and simulated annealing (SA) algorithm was proposed to solve the original task planning problem. The algorithm improves the seeking and solving ability for the global optimal result. Simulation results show the advantage of the model and the validity of DPSO-SA algorithm.
Experiment of multi-component hydrocarbon fuels RP-3 thermal conductivity
Zhou Haipeng, Wen Jie, Deng Hongwu, Jia Zhouxia
2013, 39(10): 1387-1391.
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Based on the classic trasient hot-wire princeple, the experiment apparatus for the measurement of multicomponent hydrocarbon fuel thermal conductivity under high temperature and high pressure was introduced. The calibration results of absolute ethyl alcohol, toluene and high pressure nitrogen show that the maxmum deviation for liquid thermal conductivity is less than 1% and for gas is less than 3%. After that, conductivity of domestic hydrocarbon fuel RP-3 was measured under 298~430 K and 0.1~5 MPa using this apparatus and the results show a good repeatibility. It is of great importance to improve conductivity measuring mehtods for fluid under super-critical pressure.
Degradation mechanism of air-entrained concrete under alternative actions of freeze-thaw cycles and seawater immersion
Geng Jiao, Diao Bo, Chen Shenggang
2013, 39(10): 1392-1396.
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Experiments had been done on air-entrained concrete test cubes(air content is 5.9%) experienced alternative actions of freeze-thaw cycles in the seawater to explore the properties deterioration mechanism via testing the compressive strength, the relative dynamic elastic modulus and the mass loss. Then, observing the microstructure of the concrete by scanning electron microscope (SEM). The SEM observation shows that there was barely cracks and crystals in the normally cured concrete, but cracks emerged and gradually developed as the times of freeze-thaw cycle increased. The main cracks developed further and crystals emerged in the concrete experienced 300 cycles. The results show that the alternative actions of freeze-thaw cycles and seawater immersion give rise to the emergence and development of the cracks, chemical reactions produce some dilatability crystals. Both of the physical changes and the chemical reactions make the compressive strength decrease by 8.5%, but have no apparent influence on the relative dynamic elastic modulus and the mass loss.
MCS model based on Jerk input estimation and nonlinear tracking algorithm
Zhou Zheng, Liu Jinmang, Tan Xijiang
2013, 39(10): 1397-1402.
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A new tracking algorithm was proposed for high maneuvering target based on current statistical (CS) model, modified input estimation (MIE) and unscented strong tracking filter (USTF). The state equation and adaption method of acceleration variance of the CS model were modified with Jerk input estimation. The state covariance, state noise covariance and maneuvering frequency were made jointly adaptive with the support of improved unscented strong tracking filter. The new algorithm can track continuous high maneuver, low maneuver and constant velocity motion accurately in real time when lacking prior information on acceleration. The simulation shows that the new algorithm has better adaptability, higher accuracy and faster convergence than CS-UKF, CS-USTF and interacting multiple-model (IMM) algorithms.
Distributed cooperative guidance law for multiple missiles attacking maneuver target
Sun Xuejiao, Zhou Rui, Wu Jiang, Chen Shaodong
2013, 39(10): 1403-1407.
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On the basis of distributed communication and augmented proportional guidance, a kind of distributed collaborative guidance law was designed for maneuver target intercepting based on the network synchronization principle. This guidance law was based on double layer hierarchical cooperative structure, which was composed of local guidance law and distributed coordination strategy. The local guidance law was derived from augmented proportional navigation. Based on the network synchronization principle, distributed coordination strategy which realizes coordinated attack of maneuvering targets at the same time was synthesized. Only the states of missiles were required to be communicated between the nearest-neighbor missiles within-visual-range for the distributed multiple missiles cooperative guidance law, which resulted in the characteristics of scalability and communications. The simulation results demonstrate that this distributed cooperative guidance used by multi-missiles network system can realize coordinated attack of maneuvering target effectively.
Analysis on tensile properties and influence factors of composite hybrid joints
Huang Wenjun, Cheng Xiaoquan, Wu Pengfei, Li Zhonghai
2013, 39(10): 1408-1413.
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Proper bolted or screw / bonded hybrid joint design can improve the structure efficiency. In order to solve the analysis and design problems that exist in screw / bonded hybrid composite joint structures, a 3D damage accumulation finite element analysis (FEA) model was established based on the software of ABAQUS. Non-linear properties of the adhesives and non-linear touch problems were included in this model. The analysis results of the tensile strength and damage propagation and failure of the joint structures agree with the test results. And the model effectiveness was proved. Then the influence factors such as the flange at the tip of the laminates, adhesive film thickness, adhesive toughness and contact surface friction coefficients on the joint tensile properties were studied. The results show that the flange at the laminate tip can reinforce the hybrid joint structures and improve their tensile strength. Adhesive with high toughness can improve the joint tensile strength and the film thickness almost has no effect on the strength. Higher friction coefficient between the screw pin and the hole surface can give greater joint tensile strength.
Adaptive backstepping control for flight path angle based on high gain observer
Chen Wei, Lu Jingchao, Yuan Liaoyuan, Zhang Weiguo
2013, 39(10): 1414-1420.
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An adaptive neural network high gain observer was designed to solve the problem that the states of the flight control system were not absolutely measurable. The adaptive items based on the radial basis function (RBF) network were introduced into the general high gain observer on purpose of the on-line estimation of the modeling errors and the external disturbances. With the combination of the high gain observer and the backstepping control based on the dynamic surface, an adaptive neural network backstepping control approach was proposed. The traditional problem of explosion of calculation in the backstepping control was avoided by the introduction of the first-order filter. The adaptive output feedback controller and the adaptive laws of the RBF network weight vectors were obtained on the basis of the Lyapunov stability theory. It is proved that the closed-loop system is semi-globally and uniformly bounded. The simulation results of the flight path angle control system show that the flight path angle can track the command signal without the effect of the modeling errors and the external disturbances, the convergence of the observer is concluded and the robustness of the control system is verified.

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