Advanced Search

2013 Vol. 39, No. 4

  Previous Issue | Next Issue 
Display Method:
Longitudinal flying qualities evaluation of UAV system in remote mode
Huang Chengtao, Wang Lixin
2013, 39(4): 427-431.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 654
Abstract:
The unmanned aerial vehicle (UAV) system model was established. According to the characteristics such as the communication data-link exists time delay, the UAV pilot can not directly feel the UAV g-load, etc, with the reference to piloted aircraft flight quality criterion, a means to evaluate the longitudinal flying qualities of UAV system in the remote mode is proposed.The short-period flying qualities and the pilot-induced oscillations (PIO) tendency of an unmanned aircraft were evaluated. The results show that, the communication data-link has little effect on the short period frequency and damping characteristics of the UAV. However, when the UAV pilot control the aircraft in the ground control station, the data-link delay time increases the equivalent delay time of the UAV system, which result in the closed-loop short-period flying qualities of the UAV system becomes poor, and the UAV has PIO tendency. To avoid the PIO tendency, missions of fast maneuvering flight should be avoid when the UAV was remotely piloted.
Application of ADRC technology in simulator frequency response servo
Fu Yongling, Long Manlin, Guo Dong, Niu Jianjun
2013, 39(4): 432-436.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 769
Abstract:
In simulator frequency response servo, there are some difficulties, including disturbance compensation when low frequency or low speed, a sharp deterioration of phase lag and amplitude attenuation when high frequency, the problem of conventional control strategy depending on high precise object model heavily, etc. Active disturbance rejection control(ADRC) technology which doesn’t depend on object model was introduced to solve those difficulties. Active disturbance rejection controller was designed to online observe and compensate disturbance, and pre-processing unit was designed to compensate phase and amplitude. It was applied in frequency response servo of the simulator. The measured results of tracking frequency and swept frequency according to the "Double Ten" standard were greater than the acceptance criteria of the simulator. It is showed that ADRC technology introduced in simulator frequency response servo can effectively improve frequency response characteristics of simulator.
Anti-vibration design and real-time filter methods for FOG IMU used in helicopter
Ren Yan, Fang Jiancheng, Xu Duan
2013, 39(4): 437-441.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1098
Abstract:
The bias error, nonlinear, non-gauss noise, and more arithmetic error of inertial navigation system was caused by vibration. It was a key technology to restrain the error caused by disturbance vibration. A novel method, which combining anti-vibrator and data filtering was proposed. A kinetics model of anti-vibration system for fiber optic gyroscope (FOG) inertial measurement unit (IMU) was established. The anti-vibration system can implement multi-dimension uncoupled, and eliminate vibration disturbance resource. A real-time filter method with little time delay was designed to restrain the resonance disturbance caused by anti-vibrator and random noise, and then reduce the arithmetic error. The experimental results show that the proposed method can effectively restrain disturbance vibration, reduce noise and navigation error, and help to develop a high-power head and orientation measurement system.
Stability analysis of coupled rotor/fuselage system of shipboard helicopter
Liu Yang, Xiang Jinwu
2013, 39(4): 442-446.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 771
Abstract:
A stability analysis of a shipboard helicopter which considers the asymmetric and nonlinear landing gears, is investigated to explore the coupled dynamic behavior between the rotor and helicopter. The shipboard helicopter uses bearingless rotor, and the model of the rotor considers the large deformation of the blade, the multiple-load-path of the root of blade and the constraint of lag pin and pitch link. The undercarriage system of helicopter which is a nonlinear system comprises the oleo and tyre. Firstly, the frequency and damp of helicopter under "ground resonance" has been calculated, and the result shows that the model is available. Then the frequency and damp of helicopter under "ship resonance" has been calculated, and the result demonstrates that the rolling of ship makes the rotor/fuselage system more instability, and if harpoon is deck-lock the damping of system can be increase. That is to say the harpoon can make the rotor/fuselage system more stable on-deck.
Adaptive control for aircraft anti-skid braking system based on friction force model
Li Fengyu, Jiao Zongxia
2013, 39(4): 447-452.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 514
Abstract:
The improvements of aircraft braking system reliability and efficiency are important for the safety promotion of a whole flight circle. The aircraft tire/runway friction force varies significantly on different types of runways (dry and wet, etc.), materials (asphalt and soft ground, etc.) and temperatures. This affects the braking control efficiency and even the effectiveness. The velocity correlative dynamic LuGre friction force model was introduced to describe the friction force, which could give a projective mapping from the physical unknown runway state to mathematical model with parametric uncertainties, and then the runny state could be detected through parameter estimations. Firstly, the fuselage and aircraft wheel were modeled and the state observers were employed to estimate the unmeasurable internal friction states of the friction force model. The estimates were substituted into the parameter adaptive law to obtain the current runny state. Then the online calculation of pseudo-static friction force model was applied to obtain the maximum friction coefficient and its slip rate. This slip rate was set as the tracking target for the well-designed feed-forward controller based on the feedback linearization method. At last, the simulation results were shown to prove the control effects.
Gesture consistency of airplane target between static and dynamic measurements
Li Jinliang, Zeng Yonghu, Zhou Bo, Fu Haibo
2013, 39(4): 453-457.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 630
Abstract:
Gesture consistency of airplane target between static and dynamics measurements was studied.The most common coordinate systems in target characteristics measurement were introduced, and the translation relationships were presented. The typical relative position relationship between line of radar sight and airplane target was analyzed, and the flow chart of gesture translation between static and dynamic measurements was derived. A simulation example was given. The airplane flew with a typical path, the radar track of airplane was simulated. The relative position relationship between line of radar sight and airplane target in polarization coordinate system and target coordinate system was derived while airplane is flying. The research can help to compare target characteristics between static and dynamic measurements rightly, and can also guide the dynamic simulation of target characteristics.
Improved multi-objective particle swarm optimization algorithm
Liu Baoning, Zhang Weiguo, Li Guangwen, Nie Rui
2013, 39(4): 458-462,473.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1289
Abstract:
In order to enhance the convergence and diversity of multi-objective particle swarm optimization algorithm, an improved multi-objective particle swarm optimization algorithm was proposed. The Kent mapping was used to initialize the population, and the target space was divided into several fan-shaped regions evenly. A new diversity and convergence criteria was proposed to select the optimal solutions. An improved particle swarm update formula was used for global search. The clustering algorithm was used to analyze the angles between external population and the axis, and ensure the diversity of external population. Compared with the multi-objective particle swarm optimization algorithm and the nondominated sorting genetic algorithm II, the experiment of benchmark functions simulation verifies the effectiveness of the improved algorithm.
Layout optimization of civil airplane wing structure based on automated finite element modeling
Yan Weitian, Luo Mingqiang, Liu Hu, Wu Zhe
2013, 39(4): 463-468.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 601
Abstract:
Focusing on the widely-applied two spar wing structure on civil airplanes, a wing CAD model was created parametrically according to the numbers of its stringers and ribs. Then a wing structure finite element method(FEM) model was constructed automatically by Patran command language(PCL), it was realized by 4 major steps, which were geometry model segmentation, geometry segment renumbering, segment mesh definition and FEM model generation. A complete procedure was fulfilled to construct and analyze a wing structure FEM model automatically after the numbers of its stringers and ribs had been changed, then it was integrated into a wing structure layout optimization that could be applied in preliminary design. In the end, a case study model was constructed referring to a typical civil airplane wing. Under the constraints of static strength, stiffness and skin stability, the numbers of stringers and ribs were optimized to achieve a minimum structure weight. Results show that the optimal layout brought a 10.1% structure weight reduction, which indicates the effectiveness and feasibility of the optimization.
Method for linearize power function with three parameters of incomplete accelerated degradation data
Ma Xiaobing, Chang Shihua, Chen Yunxia
2013, 39(4): 469-473.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 729
Abstract:
A method was provided to linearize the power function with three parameters. It was in view of the nonlinear prediction with the incompletely accelerated degradation paths of null bias and scale factor of accelerometer. The method was based on the assumption that the exponential parameter of power function is independent with stresses. Due to the degradation rate was faster at the higher stress than that at the lower, and its degradation amount was close to the failure threshold, while the lower were far away from the failure threshold. Therefore, the degradation trajectory at the maximum stress level can better reflect the law of the degradation models. Accordingly, a principle called the maximum average correlation coefficient at the maximum stress level to determine the exponential parameter was put forward. Through this principle, the power function with three parameters is linearized, which overcomes the poor robustness of the model prediction due to the sensitive initial value and provides an engineering method for the prediction of nonlinear accelerated degradation paths.
High-altitude heat transfer performance analysis for skin heat exchanger based on ground experiment
Dang Xiaomin, Pang Liping, Lin Guiping
2013, 39(4): 474-477.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 692
Abstract:
Facing to future high-power onboard electronic equipment cooling requirements for our country, it needs to develop a new onboard cooling technology to reduce the dependence on traditional environmental control system. A new gas-gas skin heat exchanger was studied for aircraft thermal management of electronic equipment. The skin heat exchanger is a non-energy consumption of passive heat exchanger with decreasing aircraft performance penalty when it realizes the thermal management for high-power electronic devices. To assess the heat transfer performance of skin heat exchanger onboard, an experimental prototype was designed and its heat transfer performance was carried out on the ground experimental device to obtain the convective heat transfer coefficients of its hot and cold sides. Based on this experiment, the heat transfer performance of skin heat exchanger in high-altitude cruise condition was deduced for the most unfavorable and improved installation position. This study is expected to provide technical support for its future onboard applications.
Global optimization of classified composite laminated structures based on genetic algorithms
Liu Zhenguo, Hu Jie, Hu Long
2013, 39(4): 478-483.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 861
Abstract:
A technique of global optimization aimed at composite laminated structures with high variety in distribution of stress was proposed. Under the consideration of connection and the efficiency of computation, the structure laminates were divided into regions with particular global layers and region layers on it. Special gene coding and operator were designed to match the design of division and genes of each region were treated separately in heredity. Combined with the finite element method (FEM), a subprogram written to simulate the stiff matrix of composite laminates based on classical lamination theory was used to analyze the model to get the deflection, weight and so on. as parameters of the object function and took the state whether the structure was failure or not judged by Tsai-Wu failure criterion as its condition. An example provided proves the optimized laminate structure reasonable and believable and having more efficiency in loading than one optimized in whole laminate.
Comparation of the bonding through sintering between Ag nanoparticle paste and Ag microparticle paste
Zhu Ying, Tang Shanping, Yan Jianfeng, Zou Guisheng
2013, 39(4): 484-487.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1640
Abstract:
The Ag nanoparticle paste with diameter of 20~80nm and the Ag microparticle paste with diameter of 1~3μm were used to bond Ag coated Cu discs. The shear strength was evaluated using the physical simulators Gleeble 1500D. Microstructure of the joint was studied with scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). The result shows that the shear strength of the joint using Ag nanoparticle paste is significantly higher than that of joints with Ag microparticle paste at the same parameter. The analysis of the fracture surface and interfacial of joint shows that the joint bonded with Ag nanoparticle has higher sintering density than that of Ag microparticle. In the joint bonded with Ag microparticle, there were cracks at interfacial between the copper disc and sintered silver layer, which may contribute to the low shear strength.
Assessment of monotonicity-preserving scheme for large-scale simulation of turbulence
Cui Jian, Fang Jian, Yuan Jingzhou, Lu Lipeng
2013, 39(4): 488-493.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 492
Abstract:
The high-order shock-capturing schemes were assessed by comparing the Monotonicity-Preserving scheme proposed by Suresh and Huynh (1997) with the weighted essentially non-oscillatory schemes(WENO). Great emphasis was imposed on the analysis of the performances of Monotonicity-Preserving scheme for turbulence simulation. The assessment indicates the Monotonicity-Preserving functions much better than the original weighted essentially non-oscillatory scheme, even close to the improved weighted essentially non-oscillatory scheme. In accordance with the analysis, all the assessed shock-capturing schemes can hardly emulate the high-order central scheme in simulating isotropic turbulence, which is attributed to the linear as well as nonlinear dissipation of the shock-capturing schemes. Therefore, both the linear and nonlinear dissipation should be reduced in order to improve the high-order shock-capturing schemes in preserving turbulence energy and capturing small-scale turbulence structures.
Engineering analysis of post-buckling loading capability for composite stiffened panels
Wang Feifei, Cui Degang, Xiong Qiang, Luo Xiaoqiang
2013, 39(4): 494-497.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 639
Abstract:
A project simplified theory and a method of calculating post-buckling loading capacity of composite stiffened panels based on the basic mechanics characters of composite materials were presented, which combining with FEM theory and engineering experience. Composite J-stiffened panels were taken as an example to illustrate thinking and computational formula of post-buckling analysis from the perspective of engineering. The validity and effectiveness of the method were demonstrated with the experiment. It is shown that the computing method of stability loading capability can solve the geometric non-linear analysis of composite stiffened structure load capability and keep high accuracy faced in the aerostructure design.
Application of fuzzy discrimination in reliability accelerated testing
Zheng Feng, Ai Jun, Shang Jingwei, Wang Jinhui
2013, 39(4): 498-502.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 686
Abstract:
Based on the fundamental feature of software reliability testing (SRT), similarity exited between the SRT test cases was analyzed. A serious theory in fuzzy mathematics was used to deal with the data character of test case. A new complementary fuzzy discrimination method was put forward to judge the similarity, the test case with a high similarity would not be executed but accumulate the testing time and then speed up the SRT. This method does nothing but the treatment for test case and has little impact on evaluation model. Meanwhile, it is a new attempt to software reliability accelerated testing (SRAT).
Approach based on particle filter and uncertainty graph to diagnosis for dynamic systems
Wang Dong, Li Jingwen, Feng Wenquan, Zhu Nan
2013, 39(4): 503-507.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 469
Abstract:
In model-based diagnosis of dynamic systems, the scale of state space is exponential to both the number of components and time-steps. K-Best enumeration considers only K states with maximum probabilities at each time-step, which reduces the enumeration space. But state updating is not feasible when the system is complex or the diagnostic duration is long. An approach named PF_LUG was presented, which is based on particle filter and labeled uncertainty graph. The probability of state was approximated by the number of particles sampling the state. And the traditional enumeration was replaced by label matching in back-tracking process. It reduced the computation cost of time-step by moving the term from exponent to multiplier in complexity function. The experimental results show that the running time increases linearly via time-step and outperforms K-Best enumeration apparently.
Determination and application of coarse-grain critical pre-strain curve to aluminum alloy stretch forming
Wang Kun, Wan Min, Hua Cheng, Shao Xufen
2013, 39(4): 508-511,516.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 611
Abstract:
Coarse-grain is one of the main defects in multistage stretch forming of airplane skins for aluminum alloy. An experiment of different strain paths to 2024-O aluminum alloy was designed according to the deformation state and process in skin stretch forming. The experiment process was pre-stretch, quench heat treatment and microstructure analysis, from which the relationship between grain size and deformation before heat treatment was established. The critical pre-strains of different strain paths were obtained through grid strain measurement, and the critical pre-strain curve was determined. The finite element analysis of an airplane skin was carried out combined with the critical pre-strain curve, and the coarse-grain was controlled.
Curing kinetics of epoxy resin modified with nano-particles and surface strength properties and friction coefficient
Song Qichao, Zhou Zhen, Yang Chunguang
2013, 39(4): 512-516.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 642
Abstract:
The surface strength and tribological properties of epoxy resin were modified with addition of alumina nano-particles and rubber nano-powders. The curing kinetics and the surface strength properties of epoxy nanocomposites were investigated by differential scanning calorimeter (DSC) and dynamic ultra-micro hardness tester, respectively. The friction coefficient of the composites was evaluated. The results reveal the same curing mechanism of nanocomposites as epoxy resin by showing the similar reaction order. The activation energy of nanocomposites with single kind of nano-particles was decreased while the one with mixed nano-particles was increased. The curing heat was decreased due to the suppressed curing degree by nanoparticles. The surface hardness and the elastic modulus were improved, as well as the creep-resistant and deformation-resistant properties. Conclusively, the surface strength properties and friction coefficient of epoxy composites were improved with addition of mixed nano-particles.
Improved algorithm of tracking moving objects under occlusions
Zhao Long, Xiao Junbo
2013, 39(4): 517-520.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1347
Abstract:
To better settle the problem of tracking objects under occlusions, an improved anti-occlusion tracking algorithm was proposed, based on the combination of motion prediction and adaptive multi-block template matching. The algorithm constituted the principle of detecting occlusions and the method of updating and matching multi-block templates. Kalman filter was applied to predict the object’s trajectory under occlusions. A template location rule based on the object’s velocity was adopted to re-track object after occlusion. Tracking experiments under various conditions of occlusion indicates that this algorithm succeeds to track rigid and non-rigid objects when heavily, even completely occluded, by static background. Moreover, the reliability and integrity of objects’ moving trajectories are guaranteed.
Analysis of error output characteristics of DRLG
Wang Chenchen, Wang Xinlong
2013, 39(4): 521-524,530.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 642
Abstract:
Dither structure is the key part of dithered ring laser gyroscope (DRLG), and the dither parameters directly affect its error output characteristics. In order to choose the best dither parameters and improve the measurement accuracy of this gyroscope, the effects of dither parameters on error output characteristics-bias error, scale factor error and angle random walk error of the gyroscope were analyzed deeply based on the principles of dither bias. The results show that bias error declines with the decrease of the dither magnitude; the scale factor error increases with the increase of magnitude within a certain range, but decreases above the range. Reducing the dither magnitude can reduce the error of angle random walk.
Interval analysis method for uncertain aerodynamic loads computation
Huang Ren, Qiu Zhiping
2013, 39(4): 525-530.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 541
Abstract:
The aerodynamic lift prediction problem of micro air vehicles in atmosphere due to continuous gust was studied. The uncertain von Karman spectrum parameters were expressed in the interval forms. Taking into account the uncertain flight condition, an interval analysis method was proposed to calculate the uncertain unsteady aerodynamic loads. The interval analysis method was based on interval extension and Taylor series expansion, which were combined with unsteady aerodynamic principle. The proposed method can be used to estimate the intervals of aerodynamic loads, requiring the intervals of uncertainties only, hence can be used to solve complex aerodynamic loads computation problems with uncertainties. Numerical example demonstrates the feasibility and efficiency of interval analysis method by comparing its results with probabilistic method.
Ultra-low power bulk-biased mixer with current-reuse
Shen Jing, Zhang Xiaolin
2013, 39(4): 531-534.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 513
Abstract:
Using the approaches of folded switching stage and self-biased transconductance stage, a mixer operating at supply voltage down to 0.6V was designed. The bulk-biased topology was used to achieve ultra-low supply voltage and ultra-low power consumption while the current-reuse technique was selected to increase gain, linearity and noise performance. Implemented in a SMIC 0.18μm CMOS process, the mixer core has an area of 460μm×400μm. When the frequency of the radio frequency (RF) signal, local oscillator (LO) signal and the intermediate frequency (IF) signal are 1575MHz, 1400MHz and 175MHz, respectively,the simulation results show that the mixer features a conversion gain of 6.1dB, a dual sideband (DSB) noise figure of 14dB, a 1dB compression point of -16.67dBm, and consumes only 0.76mW.
Design of chip-scale quantum interferometric magnetometer in marine environment
Guan Lijuan, Kang Zhihui, Wang Zengbin
2013, 39(4): 535-539.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1171
Abstract:
With the development of the marine environment survey, marine magnetic survey demands magnetometers with micro-size, high-precision magnetometer. The several common weak magnetic field measurement instruments were described, and an analysis of a magnetometer based on dual light-field quantum interference effects was focused on. Based on the physical mechanism of the interaction between light and atoms in a magnetic field, the interpretation of the basic principles of quantum interference effects for high-precision measurement of magnetic field was given. On this basis, the possibility of realizing a chip-scale magnetometer based on quantum interference effects was analyzed. After that, design of a chip-scale quantum interference magnetometer was discussed in detail, and the performance expectations and prospects for its application in marine magnetic survey was given.
Experimental validation of non-local property of impedance of viscoelastic material
Jin Zhongkun, Wang Tongqing, Yang Mingsui, Wang Jin
2013, 39(4): 540-543.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 764
Abstract:
Based on the definition of transmission impedance the local and non-local properties of viscoelastic material and the relationships between the impedance matrix and the frequency response matrix were described. The expression of frequency response function was derived by discretizing the acoustic pressure to equivalent node force on the surface. Based on the formula of the response function the transmission frequency response experiment was carried out when a node force acted on a viscoelastic plate. The frequency response function of the viscoelastic plate was also got by numerical method on the basis of viscoelastic dynamic finite element. The non-local properties and the experimental and numerical approaches were validated by the comparison of the two results, and these approaches can be used for other researches.
Control of fuel flow-rate supply system in high-speed airflow thermal simulation tunnel
Cai Chaozhi, Li Yunhua, Teng Fengjian
2013, 39(4): 544-548.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 488
Abstract:
According to the requirements of high speed airflow thermal tunnel simulation experiment system for fuel supply system, a fuel supply system based on variable frequency speed-regulating and bypass proportional throttle valve regulating was designed. After the analysis of the characteristics of every subsystem, the mathematical model of the system was established. Focused on the characteristic of large pure time delay existed in flow feedback of the fuel supply system, a fuzzy proportion integration differentiation (PID) prediction control strategy was proposed. The simulations and experiments show that the proposed control strategy has met the demand of the high speed airflow thermal tunnel simulation experiment system for fuel flow control quality. And the control effect is better than conventional PID and fuzzy PID control strategy.
Effect of heat treatment on duplex microstructure and mechanical properties of PM TiAl alloy
Su Meike, Zheng Lijing, Zhang Hu, Lang Zebao
2013, 39(4): 549-552,558.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 843
Abstract:
Ti-46Al-2Cr-2Nb-(B,W)(at%) alloy prepared by powder metallurgy was direct heat treated and microstructures of the alloy were obtained by cooling at different cooling rates. Results show that duplex microstructure consisting mainly of fine equiaxed γ grains and lamellar colonies were obtained at cooling rate of 50℃/min. High volume fractions of lamellar colonies result in low elongation. Structure consisting mainly of fine γ grains and α2 grains were formed at cooling rate of 10℃/min and 5℃/min. Presence of α2 phase further reduced the elongation.
Consumption forecasting of missile spare parts based on wavelet transform and revised GM-ARMA model
Zhao Jianzhong, Xu Tingxue, Ge Xianjun, Yin Yantao
2013, 39(4): 553-558.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 577
Abstract:
Aiming at the characteristic of missile spare parts consumption presenting "small sample and non-stationary", and to overcome the deficiency that traditional forecasting method builds models with abundant date sample,the combined forecast method based on wavelet transform and revised GM-ARMA was proposed to carry through consumption forecasting of missile spare parts. In the process of building a hybrid model by combining wavelet decomposition with other forecasting model,first the new parameters of wavelet functions and decomposition levels were introduced, and all the parameters as a whole for the purpose of building an optimal hybrid model were quantitatively estimated. Then the high frequency signals were forecasted with ARMA model optimized by damping least-squares method, and the low frequency was forecasted with improved GM(1,1) model based on background value optimization and transformation. Experimental results show that the combined forecasting method significantly reduces forecast errors and is valid, feasible and useful in terms of forecasting missile spare parts consumption.
Energy-saving optimization for intelligent pumps based on performance reliability restriction
Huang Bochao, Wang Shaoping, Meng Yixuan, Shi Jian
2013, 39(4): 559-563.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 553
Abstract:
Considering the variable flight profile of aircrafts and variable pressure variable displacement characteristics of intelligent pumps, a method for multiple model performance reliability analysis was developed. The transfer function models of two types operating modes were derived, the primary influencing factors were analyzed, and the phased mission reliability models were built based on the cumulative damage theory. A parameters optimization process was applied to the design of intelligent pumps, using the operating efficiency model as objective function and performance reliability index as constraint. The performance reliability of the individual operating phases was obtained for the optimized pumps, and its operating efficiency was compared with that of the constant pressure pumps, which are widely equipped in aircraft hydraulic systems. The results demonstrate that the method described tallies with the actual system operating conditions, and the high energy-saving performance of the intelligent pumps is considerable for its 15.8% more rising of average efficiency in contrast with the traditional constant pressure pumps.
Fault detection and identification for dual-redundant BLDCM system using FFT algorithm and expert system approach
Wang Xin, Zhou Yuanjun, Ma Qishuang
2013, 39(4): 564-568.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 836
Abstract:
A scheme was proposed to detect and identify faults of a dual-redundant brushless DC motor (BLDCM) system, in which high reliability and wide speed range control were required. In order to eliminate the effects of different speeds and different loads from the frequency spectrum, both of the existing current signals in each channel were processed and normalized by fast Fourier transform (FFT) algorithm. And then, a rule-based expert system provided an effective identification approach for various motor, sensor and circuit faults. Experimental results show that main faults of this BLDCM system can be correctly identified even with unexpected noise. This approach needs no more extra devices, and is proved as fast, and easy to use for the proposed BLDCM system.

Copyright © Journal of Beijing University of Aeronautics and Astronautics

Address: Editorial Department of Journal of Beijing University of Aeronautics and Astronautics, 37 Xueyuan Road, Haidian District, Beijing Post Code: 100191 Email: jbuaa@buaa.edu.cn

Supported by: Beijing Renhe Information Technology Co., Ltd.