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2016 Vol. 42, No. 5

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2016 Year 42 Volume 5 Issue E-journal
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Crack initiation approach for durability analysis on aircraft structures of a fleet
HE Xiaofan, SUI Fangyuan, WANG Tianshuai, LI Yuhai
2016, 42(5): 865-870. doi: 10.13700/j.bh.1001-5965.2015.0368
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The variability of structural properties and load spectra should be accounted for to evaluate the durability life for a fleet by the crack initiation approach (CIA), but the method to determine the life standard deviation considering the variability of structural properties and load spectra is not clear. Therefore, a durability test was conducted for the specimens of 7B04 T74 aluminum alloys stimulating the structure details of a fighter under three individual load spectra of a fleet, from which the lead crack growth data have been observed in fractograph. As a result, the parameters of P-S-N curve for this structural detail are back-extrapolated. Statistical analysis shows that the variability of load spectra has no obvious influence on the P-S-N parameters corresponding to those three load spectra. An equivalent P-S-N curve and parameter estimated method have been presented to describe the influence of load spectra in a fleet. The probability of crack exceedance is derived and the extent of damage is evaluated. Consequently, a CIA is developed accounting for both the variability of load spectra and of structural properties.
Integral kinematic calibration of 6PUS parallel mechanism
FAN Rui, LI Xi, WANG Dan
2016, 42(5): 871-877. doi: 10.13700/j.bh.1001-5965.2015.0331
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Firstly, the error Jacobi matrix of 54 parameters including the centers of U-joints and S-joints, the length of each link and the guide's position vectors was derived for the target 6PUS parallel mechanism. And the calibration model was established based on least squares method in MATLAB. The correctness of Jacobi matrix and the validity of the identification method using least squares method can be proved with MATLAB simulation. Secondly, the poses were selected based on orthogonal experiment and the integral mechanism calibration experiment was carried out by a laser tracker. The 54 parameter data were obtained through parameter identification using calibration model in MATLAB based on the calibrated results. Finally, the calibrated consequence can be obtained through error compensation. The results show that after compensation, in one direction, the maximum position error of the target mechanism is 0.030 mm and the maximum angle error is 0.0007 rad, while in three directions, the maximum position error of the target mechanism is 0.046 mm and the maximum angle error is 0.0008 rad. Therefore, we did a significant improvement in kinematic precision by integral mechanism calibration.
Multi-objective topological optimization of heat insulation structures used in high-speed train
LI Minggao, LI Ming, HAN Lu, ZHAO Hongzhe
2016, 42(5): 878-884. doi: 10.13700/j.bh.1001-5965.2015.0539
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For the high-speed train, the characteristics of heat insulation structures are the significant consideration in performance evaluation. The structures utilized in floor, side-wall, and ceiling are researched. The objective of this paper is to improve their performances of stiffness, heat insulation and weight. The thickness of profile would be reduced (the thickness of blanket of glass wool would increase) by parameter optimization in order to improve the heat-insulating property. The topological optimization is implemented to change the load transfer path and to enhance the stiffness of structures. The optimized result is hence achieved, and the manufacturability process is carried out. Finally, the performances of stiffness, heat insulation and weight are improved. And the effectiveness of the analysis is validated by finite element simulation. Consequently, this paper can provide quick calculations for the heat insulation structures of high-speed train.
Improved particle filter algorithm based on chaos particle swarm optimization
WANG Ershen, PANG Tao, QU Pingping, LAN Xiaoyu
2016, 42(5): 885-890. doi: 10.13700/j.bh.1001-5965.2015.0670
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To solve the degeneracy phenomenon and the sample impoverishment problem of basic particle filter (PF) algorithm, which makes the particles of PF algorithm unable to express the real distribution of probability density function, a novel PF algorithm based on chaos particle swarm was proposed. Chaos sequence was adopted in this proposed algorithm. The chaos sequence was used to generate a set of chaotic variables, which was mapped to the interval of optimization variables to improve the quality of particles. And chaos perturbation was utilized to overcome the search being trapped in local optimum for particle swarm optimization (PSO) algorithm. The univariate nonstationary growth model (UNGM) was used for simulation to compare the proposed algorithm with basic PF and particle swarm optimization particle filter (PSO-PF). Under the conditions of Gaussian and non-Gaussian noise, the performances of the proposed algorithm had been verified by the simulation. The results show that the performances of the number of effective particles and root mean square error (RMSE) in the algorithm are better than the performances of the basic PF and the PSO-PF algorithm. Therefore, the accuracy and tracking performance of PF are improved.
Aeroengine sensor data reconstruction with missing data
ZHOU Yuan, ZUO Hongfu, HE Jun
2016, 42(5): 891-898. doi: 10.13700/j.bh.1001-5965.2015.0350
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Aiming at handling incomplete sensor data, we propose an online-reconstruction model based on the polar incremental matrix completion (PIMC) algorithm for aeroengine sensor data, which can represent the evolving features of system by subspace. The model extracts the current data feature from the history data and updates the subspace to track the evolving features via new data. The proposed model was validated and compared on two simulated datasets and the normalized mean square errors (MSE) between the reconstruction by PIMC and the ground truth are all less than 1×10-5. The experimental results show that the proposed model is practical for aeroengine sensor data reconstruction, which is robust to missing data and noise.
Test method of elliptical hydraulic bulging based on constant strain rate
SUN Zhijia, YANG Xiying, LANG Lihui
2016, 42(5): 899-905. doi: 10.13700/j.bh.1001-5965.2015.0653
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To determine the forming limit curves (FLCs) of 2A16-O aluminum alloy sheet at various temperatures and strain rates, a modified Hollomon equation is put forward to acquire the fitted true stress-true strain curve. Through finite element analysis (FEA), the fracture position in elliptical hydraulic bulging with different ovality was obtained. The forming limit data in specified strain path were determined by optimizing the process parameters. The quantitative relation between pressure rate and strain rate was derived by establishing the formula of liquid pressure, equivalent strain and strain rate. By combining the uniaxial tensile with elliptical hydraulic bulging which is controlled by the constant strain rate, the FLCs of 2A16-O aluminum alloy sheet at different temperatures and strain rates were acquired. The above method provides the criterion for quantitatively analyzing the influence rule of strain rate on FLCs and evaluating which theoretical method is more accurate to predict FLCs.
Application of multi-axial fatigue life estimation methods to aircraft structural components
SONG Enpeng, LU Hua, HE Gang, WANG Mingchun, LIU Tianqi, BAO Rui
2016, 42(5): 906-911. doi: 10.13700/j.bh.1001-5965.2015.0322
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The fatigue life of a typical aircraft structural component, which is subjected to a representative proportional multi-axial stress state, was evaluated using three different multi-axial fatigue life estimation models. Comparisons between the evaluation results obtained by multi-and uni-axial fatigue models and those with the test results were performed. Finite element analysis indicates that plasticity strain is significant on the fatigue critical details when the structure endurance reaches 88% of the peak load, therefore, low-cycle fatigue (LCF) life prediction models are reasonable. Three LCF models based on critical plane theory are selected to estimate the fatigue life of the structure, i.e., Wang-Shang's model, Smith-Watson-Topper(SWT)'s model and Morrow-Brown-Miller's model. Multi-axial fatigue test was also conducted to investigate the validity of the models for engineering application. The comparison results are as follows. The estimatied results of the three multiaxial models are all conservative, in which Wang-Shang's model gives a relatively smaller error and is acceptable for such structures. The errors of SWT's model and Morrow-Brown-Miller's model are much greater. For the fatigue assessment of such structural components subjected to multi-axial loading, multi-axial fatigue life estimation methods must be used since the uni-axial fatigue life method will give too dangerous estimation.
Potential production of microalgae aviation fuel and CO2 emissions reduction in China
REN Haitao, GUO Fang, YANG Xiaoyi
2016, 42(5): 912-919. doi: 10.13700/j.bh.1001-5965.2015.0359
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Based on the variation of temperature and the available supply of water resource and carbon dioxide, the appropriate location for Nannochloropsis cultivation in China was investigated in this study. The potential of microalgae and microalgae aviation fuel annual yield is also predicted according to carbon dioxide emissions from coal-fired power plant and the data of Nannochloropsis cultivation at Penglaiin 2013. The results of life-cycle analysis model GREET indicate that the microalgae aviation fuel could reduce the carbon dioxide emission compared with the fossil aviation fuel in life cycle assessment. China could produce 88.94 million t microalgae that could be converted to 19.17 million t aviation fuel every year. Compared with the fossil aviation fuel, production of one t of microalgae aviation fuel can reduce 2.28 t of carbon dioxide emissions according to the assessment of the whole life cycle.
Eliminating magnetic disturbance of satellites by method of magnetic field gradient tensor measurement
ZHANG Yiteng, LI Lei, ZHOU Bin, WANG Jindong, FENG Yongyong
2016, 42(5): 920-926. doi: 10.13700/j.bh.1001-5965.2015.0356
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Based on the investigation of eliminating magnetic disturbance of satellites, in the way of magnetic field gradient tensor measurement method instead of traditional bi-sensor gradient method, simulation and physical test were carried out to eliminate the satellite magnetic disturbance due to its main body, and the relationship among the structural index of Euler deconvolution algorithm, the boom length and the background magnetic field inversion error was investigated. Simulation results show that according to 1m side length and 1 A·m2 remnant magnetism of cube satellite, magnetic field gradient tensor method has lower inversion accuracy of the background magnetic field under the short boom condition of 1-2 m, and higher inversion accuracy under the long boom condition of more than 3 m, which is about 0.5 nT under the condition of 4 m length boom. Under the long boom condition, the accuracy is approximately 3 times higher than that of the bi-sensor gradient method.
Approach based on template for engineering drawing
CHEN Youdong, LI Jianyou, YOU Wei
2016, 42(5): 927-933. doi: 10.13700/j.bh.1001-5965.2015.0313
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To solve low efficiency caused by a variety of engineering drawing styles, we proposed an approach based on template to generate the engineering drawing. The engineering drawing is abstracted into a complex form. Using the template technology for the form, the engineering drawing templates architecture is constructed. According to the characteristics of data, we design three strategies for input data. We take a string as the parameter name, and the string is the data interface between template and data. The templates are abstracted from the engineering drawing styles. The engineering drawings are generated by filling the template with data and adding a set of projection views. By using CATIA component application architecture(CAA), we have developed software system for the fast generation of engineering drawing. Through the verification by the software system, the effectiveness of the proposed method that improves the efficiency of the engineering drawing generation was confirmed.
Cooperative localization algorithm of multi-UAVs based on dynamic hybrid belief propagation
WAN Jiuqing, BU Shaocong, ZHONG Liping
2016, 42(5): 934-944. doi: 10.13700/j.bh.1001-5965.2015.0321
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A dynamic hybrid belief propagation algorithm for cooperative localization of multiple unmanned aerial vehicles (UAVs) was proposed. In the case that the GPS signals of some UAVs are missing, the position and velocity of each UAV in the group in an online and distributed manner based on the GPS observations of other UAVs, the relative distance measurements between neighboring UAVs, and the outputs of accelerometer of each UAV were estimated by the algorithm. Specifically, the joint belief state of multiple UAVs by factor graph was modeled, and the marginal posterior distribution of each node in the graph was calculated, corresponding to each UAV, using the hybrid dynamic belief propagation algorithm. The inference only involves local information processing on each UAV and mutual information exchanging among neighboring UAVs, allowing the algorithm to be implemented in a completed and distributed manner. The results show that the effectiveness of the method by comparison with traditional cooperative localization algorithms in simulations.
Effects of cowling design on aerodynamic performance of airfoil with BLI
XIANG Yang, WU Jianghao, ZHANG Yanlai
2016, 42(5): 945-952. doi: 10.13700/j.bh.1001-5965.2015.0802
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Boundary layer ingestion (BLI) effect significantly influences aircraft aerodynamic performance. Cowling design further affects aerodynamic performance of airfoil with BLI effect. To clarify the effect and its reason of main cowling design parameters on aerodynamic performance of an airfoil with BLI effect, a detailed study was investigated by computational fluid dynamics (CFD) method and Morris sensitivity analysis method. Sensitivity order and coupled effect order of main parameters on aerodynamic performance were obtained. Flow details of parameters with higher sensitivity and greater coupled effect were analyzed. The results show that in cruise and take-off conditions, the parameters with relatively great impact are cowling maximum thickness and inlet location along the chord direction. The main reason of effects of cowling maximum thickness on aerodynamic performance is that local stall occurs at cowling surface. The variation of cowling maximum thickness also affects the variation trend of plot of drag coefficient to mass flow rate. The coupled effect of cowling maximum thickness and inlet location along the chord direction on aerodynamic performance is relatively great.
Profile optimization of multi-diversion combination inducer and impeller
LI Jia, LI Huacong, WANG Shuhong, XU Xuan
2016, 42(5): 953-960. doi: 10.13700/j.bh.1001-5965.2015.0328
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As the research objective is to optimize the performance of the combination multi-diversion inducer and impeller, this paper carries out the profile optimization study based on the correlation analysis of profile parameters with the structural parameters. Using the least square method, we obtained the fitting profile of the impeller, then compared the computational fluid dynamics (CFD) simulation results of the fitting model with the experimental results of the original model. The contrast shows that the error values of head and efficiency are less than 2%, and identifies the fitting method's accuracy. Finally, we compared the performances of the different fitting models through analyzing the correlation between fitting coefficient and impeller's inlet and outlet structural parameters. The results show that the internal flow fields of the three fitting models are stable. The impeller outlet and volute tongue have some low-pressure areas, and a certain high-speed group exists at the diffuse outlet because of the influence of vortex flow at the tongue. Ultimately, the head and efficiency of profile-3 are most optimized and obviously at the design point.
Analytical solutions of steady glide trajectory for hypersonic vehicle and planning application
HU Jinchuan, ZHANG Jing, CHEN Wanchun
2016, 42(5): 961-968. doi: 10.13700/j.bh.1001-5965.2015.0330
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A kind of analytical solving method for the three-dimensional steady glide trajectory of the hypersonic vehicle is presented in this paper for the online planning problem. Firstly, the lift coefficient is separated into three components of lateral component, steady glide normal component and equilibrium glide normal component. Then, the longitudinal trajectory, lateral trajectory and velocity are decoupled in the dynamics. After that, the solutions of height, downrange and velocity azimuth angle are obtained by the analytical integration and the regular perturbation method, while the solutions of longitude, latitude and velocity are obtained by the Gaussian quadrature and single-step Runge-Kutta integration separately, and the accuracy of those solutions are improved by increasing the computational steps. Finally, a rapid steady glide trajectory programming algorithm is proposed based on the above analytical solutions, and the planning parameters are the lateral lift coefficient and steady glide normal lift coefficient. The simulation results show that those analytical solutions are more accurate than the Bell's solutions, and the planning algorithm only needs a small amount of calculation and obtains the result quickly, which can be used for online trajectory planning.
Test and characterization model on fatigue behavior for pre-corroded metallic aircraft materials
FU Yu, XIONG Junjiang
2016, 42(5): 969-976. doi: 10.13700/j.bh.1001-5965.2015.0348
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New S-N-t surface model was proposed for characterizing fatigue behavior of pre-corroded metallic materials and novel formulae were derived to estimate the parameters of the proposed model. Fatigue life-group and up-down tests were conducted on un-notched and notched pre-corroded specimens for three different types of metallic aircraft materials (LD2CS, LD10CS and 15CrMnMoVA)to determine the fatigue S-N-t surface. Good agreements were achieved between the test and the new S-N-t surface models by applying the new proposed S-N-t surface model to the test data points. Fatigue behavior of un-notched and notched pre-corroded metallic aircraft materials decreases with the increase of pre-corrosion time. The un-notched specimens show better fatigue behavior than notched ones at the same stress level and pre-corrosion time.
Far-field aeroacoustic experimental study of flow around a circular cylinder at subcritical Reynolds number
LI Ling, LIU Peiqing, XING Yu, GUO Hao, TIAN Yun
2016, 42(5): 977-983. doi: 10.13700/j.bh.1001-5965.2015.0364
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To study the aeroacoustics of the flow around a circular cylinder at subcritical Reynolds number, the experimental investigation of far-field aerodynamic noise generated from flow past a circular cylinder was carried out in D5 aeroacoustic wind tunnel at Beihang University. Under variable flow conditions in the D5 test section, the signal of the sound pressure obtained from the free-field microphones at different positions in the anechoic chamber was measured. The dependence of far-field noise on free stream velocity and receiver position was acquired with the fast Fourier transform(FFT). With the qualitative and quantitative analysis of the aeroacoustic characteristics, the experimental results validate that the noise emitted from the circular cylinder is the largest in the direction vertical to the flow and decreases with the angle increasing, belonging to the characteristics of the sound radiated from a dipole sound source. The far-field aerodynamic noise generated from the cylinder is proportional to the sixth power of flow speed and inversely proportional to the twice power of the distance between the receiver and the center of the circular cylinder, confirming the domination of the dipolar noise source.
Hopping ability of gas fuel powered hopping robot on different grounds
LUAN Yunguang, WANG Huaming, ZHAO Dongbiao, WANG Yang, CHEN Fenghong
2016, 42(5): 984-991. doi: 10.13700/j.bh.1001-5965.2015.0365
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Gas fuel powered hopping robot has great traverse obstacle ability, but its performance is affected by ground mechanical properties greatly. For exploring ground influence on the hopping robot performance, the dynamic model of the robot is analyzed by theory and experiments during take-off process. Firstly, hopping robot taking off dynamic model is set up and the reaction force between ground and robot foot is analyzed according to the Hunt-Crossley contact model. Secondly, the test platform is set up to test the static and dynamic contact model relative parameters on hard clay soil and grass soil. Finally, the hopping mechanism test experiments on rigid ground, hard clay ground and grass ground are conducted and analyzed respectively. When 0.01 MPa propane and 0.21 MPa nitrous oxide are injected in hopping actuator, 3.55 kg hopping mechanism can hop 2.0 m and 1.4 m on rigid ground and hard clay ground respectively, while the pressures of the chamber are basically the same. The maximum pressure inside the chamber is about 3.1 MPa. On the grass ground, the hopping height is 0.1 m when 0 MPa gas source is filled in the chamber. The result shows that robot hops lower on soft ground than rigid ground and experiments fit well with the analysis results on the three grounds.
Thermal flux compression algorithm to enhance RRAM reliability
XIANG Zhongyuan, ZHANG Feng
2016, 42(5): 992-998. doi: 10.13700/j.bh.1001-5965.2015.0336
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A thermal flux compression (TFC) algorithm is proposed through the research on the thermal crosstalk in resistive random access memory (RRAM) to strengthen the RRAM reliability. By adding TFC algorithm before RRAM read-write circuit and reducing Joule heat produced in RRAM, thermal crosstalk in RRAM could be weakened and RRAM reliability could be enhanced. With the analysis and computation of real Joule heat produced in write data flow, TFC algorithm could judge whether to flip data, in order to reduce the Joule heat in RRAM, that is, TFC algorithm would choose the one with lower thermal flux between original write data flow and flipped encode data flow through the algorithm layer. Theoretical analysis and simulation results show that TFC algorithm could reduce more than 30% write Joule heat on average and valuation of resistive unit retention could increase by over 35% on average, with byte as the unite data block.
Aeroservoelastic unstability failure analysis in special wind tunnel test
TANG Bo, WU Zhigang, YANG Chao, MA Chengji
2016, 42(5): 999-1007. doi: 10.13700/j.bh.1001-5965.2015.0339
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In an already completed wind tunnel test where a flight control system was applied, the vibration divergence of the test model under big closed-loop gain has drawn our attention. To find the mechanism of this failure, the frequency analysis of the test data has been done and the servo stabilization under no wind condition has been examined. Also, we built a simplified structural mechanic model according to the real situation and investigated the problem by analyzing the related differential equation of motion. The main cause for this failure has been found:the unexpected elastic effect after the involving of support system is significant and thus the coupling of elastic structure, control system and aerodynamic force gives rise to the aeroservoelastic instability. In addition, a numerical simulation has been done and verified the above mechanism. To solve this divergence problem, two improvements/solutions for the control system have been brought up:adding a structure filter in the feedback loop or changing the gain parameters of different control surfaces. Also, both the solutions have been verified by numerical simulation. The solution of adding a structure filter has been applied in the real wind tunnel test and expected effect has been achieved.
SEU soft error effect modeling and simulation method for navigation satellite
FAN Jiping, JIAO Jian, ZHAO Haitao, ZHAO Tingdi
2016, 42(5): 1008-1015. doi: 10.13700/j.bh.1001-5965.2015.0325
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Single event upset (SEU) soft error is one of the most important factors that affect the reliability and availability of satellite. To analyze and evaluate the SEU soft error propagation and effect in navigation satellite system, a novel finite-state machine (FSM)/Stateflow modeling method is proposed, where the basic model elements and modeling principles combined with protection and recovery strategies in satellite are presented. Through the simulation based on Simulink/Stateflow platform, the availability of satellite and mean task interruption time are obtained, and the effects of several recovery strategies on the availability of satellite are analyzed; moreover, a co-simulation between MATLAB and STK is conducted to evaluate the constellation positioning dilution of precision (PDOP) availability obtained from the simulation result of single satellite soft error propagation, which reflects the impacts of SEU soft error on both single satellite and constellation.
Prediction on in-plane compression elastic properties of satin weave composites with pore matrix
BIAN Tianya, GUAN Zhidong, LIU Faqi, WANG Renyu, MU Junwu
2016, 42(5): 1016-1024. doi: 10.13700/j.bh.1001-5965.2015.0312
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Because of the complex meso-structure of satin weave composites, it is difficult to apply traditional methods to prediction on elastic properties. For this problem, the representative volume element (RVE) of satin weave composite was established and research on prediction on effective in-plane compression modulus and in-plane Poisson's ratio of the RVE was made. Longitude compression modulus of bending fiber yarns and properties of pore matrix were calculated based on energy method and inclusion theory, respectively. Traditional rules of mixtures formulations were improved so as to get an accurate analytical prediction on in-plane compression modulus and in-plane Poisson's ratio of the RVE. The model of the RVE was established based on Python language being used in the finite element method software ABAQUS. Prediction on effective in-plane compression modulus and in-plane Poisson's ratio was made based on finite element method results of the model under the basic forced state. The error between analytical method and numerical simulation is small, which gives an excellent prediction on in-plane compression modulus and in-plane Poisson's ratio of carbon/carbon satin weave composites.
Time-varying convex optimization for spare parts inventory considering passivation
SONG Changhao, GUO Linhan, WANG Naichao, MA Lin
2016, 42(5): 1025-1031. doi: 10.13700/j.bh.1001-5965.2015.0327
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Taking passivation into consideration, we apply a time-varying inventory balance equation to setting up the time-varying backorder formula and use the extended Palm theorem to combine the cumulative demands for spare parts with the parameters of the shape characteristics of Poisson processes to create a convex optimization algorithm for spares considering the cumulative demands. Next, we use time-varying availability as the optimization objective under a cost constraint to obtain the optimal configuration program in every period by convex optimization methods. A selection rule known as the mode method is introduced to select the proper global stock policy. Finally, a numerical example is presented to demonstrate the approach, and several inventory policies are compared to prove the superiority of the proposed method.
Failure mechanism analysis of different types of manufacture for composite stiffened panels under axial compression load
XU Rongzhang, GUAN Zhidong, WANG Renyu, JIANG Siyuan
2016, 42(5): 1032-1038. doi: 10.13700/j.bh.1001-5965.2015.0335
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In order to research the failure mechanism of secondary bonding and co-curing stiffened panels under axial compression load, test and numerical calculation were conducted for different types of manufacture of composite stiffened panels with edge constraint. In the test, strain gage was pasted to timely monitor the local buckling, while the load corresponding to initial acoustic emission was detected and fracture cross-section was observed to investigate the fracture mechanism. Based on the ABAQUS software, a finite element was observed to simulate the post-buckling-progress and damage progress. The calculated results are coordinated with the tested results very well. The results indicate that manufacture has no impact on the stability and load capacity, while the structure types have significant influence. Polymethacrylimide (PMI) foam can delay the occurrence of initial damage, even though it cannot increase the buckling load and ultimate load of panels. Initial damage of interface of secondary bonding panels occurs at a time close to fracture, while that of co-curing panels occurs early and extends slowly, so co-curing panels show better behavior of damage resistance.
Combat capability requirement generation of warship area air defense based on constrained optimization
XU Junfei, XING Changfeng, WU Ling
2016, 42(5): 1039-1045. doi: 10.13700/j.bh.1001-5965.2015.0337
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Capability requirement generation is performed under multiple constraints, so seeking the constraint set is its focus. In the background of area air defense of ship-to-air missile, by extracting the constraint set that has an effect on generation of capability index through the comprehensive analysis of combat requirement constraints, capability requirement constraints, technology development constraints and other constraints, the target function of warship air defense combat effectiveness was established, and we solved constrained optimization of capability index through particle swarm algorithm based on the penalty function method. The curves of the other combat capability indices before and after optimization were simulated and verified with the max distance of early warning as the variable. Finally the capability indices produced verify the feasibility of the model and algorithm and provide quantitative basis for combat capability requirement generation of warship area air defense.
Corrosion resistance of sulfuric-adipic acidic film for 2198 aluminum alloy
WANG Xuefei, LI Songmei, LIU Jianhua, YU Mei, LI Yingdong
2016, 42(5): 1046-1054. doi: 10.13700/j.bh.1001-5965.2015.0342
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2198 Al-Li alloys were anodized in sulfuric-adipic acid bath, and then protected by boiling water sealing treatment. The surface morphology and cross-sectional morphology of the anodic film were evaluated by field emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM).The corrosion properties of the anodic film were analyzed by electrochemical impedance spectroscopy (EIS), Tafel curve and immersion test. The anodic samples were respectively immersed in sodium chloride solution for different time, then EIS was used to analyze the corrosion behavior. The results show that some holes of the anodic film are connected because of the copper alloy phases. The result of EIS shows that the corrosion resistance of the anodic film after sealing treatment increases obviously, equivalent circuit changes with extension of immersion time, and the impedance of the porous and barrier layers decreases, so immersion process could change the structure of the anodic film and decrease the corrosion resistance.
A multi-Agent negotiation based collaborative optimization application in satellite design
DONG Yunfeng, WEI Xiaona, HAO Zhao
2016, 42(5): 1055-1064. doi: 10.13700/j.bh.1001-5965.2015.0640
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Satellite design is a complex problem of multidisciplinary optimization.Collaborative optimization algorithm, with its feature of modularization, is suitable for being applied to the multidisciplinary optimization of satellite design. To guarantee the consistency of shared variables between the system level and the subsystem level, the traditional collaborative optimization has the limitation such as convergence dilemma and excessive computational cost. And the traditional collaborative optimization which cannot optimize the subsystems cannot ensure the optimization of satellite overall performance. This paper proposes a multi-Agent negotiation based collaborative optimization algorithm by introducing the concept of Agent-based model and multi-Agent negotiation. We take earth observation satellite as an example, and with the object that the total weight is the minimum, a system-level Agent model and four subsystem-level Agent models including structure subsystem, orbit subsystem, attitude subsystem and power subsystem are built. The results indicate that the multi-Agent negotiation based collaborative optimization algorithm can ensure the consistency of shared variables, and the subsystem optimization model ensures that the subsystems are optimal when system-level optimization is carried out.
Adaptive evaluation method based on analytic hierarchy process
ZHANG Yaotian, ZHANG Xucheng, JIA Mingshun, XUE Xiangshang
2016, 42(5): 1065-1070. doi: 10.13700/j.bh.1001-5965.2016.0224
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In order to improve the performance of classical analytic hierarchy process (AHP) which has defects of subjectivity and less quantitative component, at the same time according to the objective information which is implied by a plurality of target data matrix, the classical AHP was modified and a changeable weight evaluation method based on AHP was proposed. The conclusion is that the new method is able to adjust the weights of the evaluative parameter dynamically by analysis of the data distribution. By this way the weight of low discrimination index is reduced while the weight of high discrimination index is improved, which makes the AHP more objective, and to some extent the guiding role of the scarcity index is also reflected. The effectiveness of the new method is verified by using the example of the evaluation of the despeckling algorithm of synthetic aperture radar image.
Optimization of double-impulse rendezvous using gradient-splitting interval optimization algorithm
LIU Qi, ZHU Hongyu
2016, 42(5): 1071-1078. doi: 10.13700/j.bh.1001-5965.2015.0324
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Abstract:
The optimal problem of time-open double-impulse rendezvous was studied and the gradient-splitting interval optimization algorithm (GIOA) was introduced. Considering the characteristics of the problem, GIOA utilized the interval selection strategy which selected a finite number of subintervals to compute, the interval splitting strategy based on the result of the gradient optimization algorithm, the interval contraction strategy based on monotonicity, the test of constraints and the updating strategy of target estimated value based on gradient, etc. As the gradient-algorithm was only used for the interval splitting strategy and the updating strategy of target estimated value, it had no negative effect on GIOA's inheriting of the global characteristic and convergence of the interval optimization algorithm. Simultaneously it accelerated the appearance of an interval containing the optimal value with small width and the updating rate of target estimated value. Thereby the operation efficiency was improved. By the interval selection strategy, the increase of subinterval numbers has been controlled, and the storage costs have been reduced. In the simulation, GIOA solves the optimal problem of time-open double-impulse rendezvous successfully, and shows the advantages of the algorithm.
Pressure oscillation characteristics of n-butanol/kerosene mixture in non-premixed combustor
XU Sai, XU Quanhong, LIN Yuzhen, HUO Weiye, QIN Hao
2016, 42(5): 1079-1084. doi: 10.13700/j.bh.1001-5965.2015.0323
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Abstract:
To further develop the application of the biomass fuel in gas turbine combustor, the wave convection model was conducted based on the experimental results to quantitatively analyze the influence of n-butanol/kerosene mixing ratios on the pressure oscillation frequencies in a non-premixed combustor. The experimental results show that the pressure oscillation frequencies decrease with the increasing volume proportion of butanol under the experimental condition of com bustor inlet pressure 1.98 MPa, inlet temperature of 600 K and fuel/air ratio of 0.03. However, the amplitudes have no significant changes with the increase of volume proportion of butanol. The results of wave convection model are in good agreement with the experiment data. The calculation results show that the variation of convective time caused by the variation of heat value of different fuel components is the main cause of the variation of pressure oscillation frequencies. It provides reference for the control of pressure oscillation in a non-premixed combustor.
Finite thrust spacecraft approaching trajectory planning based on genetic programming
WEI Xiaona, DONG Yunfeng, HAO Zhao
2016, 42(5): 1085-1092. doi: 10.13700/j.bh.1001-5965.2015.0573
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Abstract:
Based on the genetic programming algorithm with the introduction of the basis function, this paper proposes a new way to deal with finite-thrust spacecraft trajectory optimization when approaching a non-cooperative object in the final approach phase. Thruster switch state is defined as the basis functions which respectively multiply by the switch state duration and then sum as the thruster state function. The thruster state function is converted into genetic programming tree structure. Fuel consumption is defined as the fitness function of genetic programming, and the constraint conditions of obstacle avoidance and approaching precision are induced into the fitness function in the form of penalty function. Genetic programming algorithm is used to obtain the optimal-fuel trajectory planning scheme by training all the possible combinations of thrusters switch state. The result is global optimal, and the thrusters switch frequency is not high. The trajectory planning result based on finite thrust of a spacecraft approaching non-cooperative object shows that the thruster is only opened and closed 5 times, greatly reducing the requirement for switching frequency. Approaching time is reduced by 30.09% compared with the Gauss pseudospectral method, and fuel consumption is reduced by 4.18%.

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