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Xu C.-D.,Beijing Institute of Technology | Pei X.,Beijing Institute of Technology | Pei X.,Army Aviation Institute of PLA | Liu Y.-B.,Tsinghua University | Zhang L.,Tsinghua University
Jisuanji Jicheng Zhizao Xitong/Computer Integrated Manufacturing Systems, CIMS | Year: 2010

To push advanced concepts of modern condition-based maintenance and improve the helicopter attendance rate and operational readiness, after analyzing the requirements of helicopter Maintenance, Repair and Overhaul/Operations (MRO) information system, information and network technology was applied in helicopter maintenance system, and a maintenance policy supporting regular maintenance and state maintenance was proposed. Based on Open System Architecture for Condition-Based Maintenance (OSA-CBM), the MRO information system architecture for helicopters was constructed. Finally, deployments of helicopter MRO system were discussed.


Ma X.,Tsinghua University | Lin F.,Tsinghua University | Yao B.,Tsinghua University | Yao B.,Army Aviation Institute of PLA
Chinese Journal of Mechanical Engineering (English Edition) | Year: 2016

In Additive Manufacturing field, the current researches of data processing mainly focus on a slicing process of large STL files or complicated CAD models. To improve the efficiency and reduce the slicing time, a parallel algorithm has great advantages. However, traditional algorithms can't make full use of multi-core CPU hardware resources. In the paper, a fast parallel algorithm is presented to speed up data processing. A pipeline mode is adopted to design the parallel algorithm. And the complexity of the pipeline algorithm is analyzed theoretically. To evaluate the performance of the new algorithm, effects of threads number and layers number are investigated by a serial of experiments. The experimental results show that the threads number and layers number are two remarkable factors to the speedup ratio. The tendency of speedup versus threads number reveals a positive relationship which greatly agrees with the Amdahl's law, and the tendency of speedup versus layers number also keeps a positive relationship agreeing with Gustafson's law. The new algorithm uses topological information to compute contours with a parallel method of speedup. Another parallel algorithm based on data parallel is used in experiments to show that pipeline parallel mode is more efficient. A case study at last shows a suspending performance of the new parallel algorithm. Compared with the serial slicing algorithm, the new pipeline parallel algorithm can make full use of the multi-core CPU hardware, accelerate the slicing process, and compared with the data parallel slicing algorithm, the new slicing algorithm in this paper adopts a pipeline parallel model, and a much higher speedup ratio and efficiency is achieved. © Chinese Mechanical Engineering Society and Springer-Verlag Berlin Heidelberg 2016.


Yao B.,Tsinghua University | Yao B.,Army Aviation Institute of PLA | Lin F.,Tsinghua University | Ma X.,Tsinghua University
Xiyou Jinshu Cailiao Yu Gongcheng/Rare Metal Materials and Engineering | Year: 2016

In the process of laser micro cladding deposition manufacturing of TC4, the influence of the laser power and scanning speed on the microstructure and micro-hardness were analyzed. The results indicate that the prior β columnar grains dominate the entire cladding layer or the columnar are epitaxial growth with a thin layer of fine dendritic microstructure in the top. There are two regions, bright region and dark region in the macrostructure. When P/V is less than 40 W·s·mm-1, the bright region is in the top and the dark region is below it. The microstructure of the two regions is acicular martensite and it is finer in bright region than in dark region. The micro-hardness of the bright region is higher than that of the dark region. With the increase of the laser power or the decrease of the scanning speed, the height of the bright region increases and the micro-hardness of the bright and dark regions all decreases. Otherwise, the bright region is under the dark region. In this case, the microstructure of the bright region is still acicular martensite, while the microstructure of the dark region is coarsened from acicular martensite by a solution and aging treatment of the repeated heating; at the same time, the micro-hardness of the dark region is higher than the bright region. © 2016, Science Press. All right reserved.


Wang S.,Harbin Institute of Technology | Chen R.,Harbin Institute of Technology | Zhang L.,Harbin Institute of Technology | Wang S.,Army Aviation Institute of PLA
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2010

The aerospace power is widely used in the aerospace system. Its reliability directly affects the safety of the whole system. However, the particles generated in the production process usually cause failures to the aerospace power. In this paper, a novel automatic detection method for particles in the aerospace power is proposed based on Particle Impact Noise Detection (PIND) test. Firstly, stochastic resonance algorithm is presented to detect the existence of tiny particles. Secondly, in order to obtain the sources of particles, wavelet packet transform is used to extract energy distribution vectors of different material particles, and Learning Vector Quantization(LVQ) network is brought in for material identification of particles. Finally, the results indicate that the accuracy meets the requirements of practical application. © 2010 Springer-Verlag.


Wang S.,Harbin Institute of Technology | Chen R.,Harbin Institute of Technology | Zhang L.,Harbin Institute of Technology | Wang S.,Army Aviation Institute of PLA
Transactions of the Institute of Measurement and Control | Year: 2012

The detection of loose particles inside an aerospace power supply is important to improve the reliability of the whole space system. This paper investigates the detection and material identification of loose particles within an aerospace power supply based on the particle impact noise detection (PIND) test. A stochastic resonance algorithm is employed to detect the presence of tiny particles. A learning vector quantization (LVQ)-based material identification method is proposed. Finally, experiments are conducted to demonstrate the effectiveness of the proposed technique. Experimental results show that the accuracies of particle detection and material identification are above 90% and 80%, respectively, which meets end-user requirements. © The Author(s) 2011.


Yang Q.,Beijing University of Technology | Yang S.,Beijing University of Technology | Yang S.,Hebei University | Lin X.,Army Aviation Institute of PLA
Computers, Materials and Continua | Year: 2015

An equivalent continuum model of an isogrid structure is utilized to analyze the impact response of isogrid structures and stiffened structures. The parameters of the equivalent model are determined, and the comparison between the equivalent continuous structure and the real grid structure are examined to validate the reliability of the equivalent model. Then, the impact responses of stiffened cylindrical shells with and without an elliptical hole are investigated by using the equivalent model of grid structures. For a different location and geometry of the elliptical hole, the deformation and load-bearing capacity of the grid-stiffened cylindrical shells are studied. The numerical results indicate that the present equivalent model can be applied effectively in simulation for the impact behavior of the grid and stiffened structures. This work provides a comprehensive understanding for the impact performance of the complicated stiffened cylindrical shells. Copyright © 2015 Tech Science Press.


Kong L.-Z.,CAS Institute of Electrical Engineering | Kong L.-Z.,University of Chinese Academy of Sciences | Kong L.-Z.,Army Aviation Institute Of Pla | Tang X.-S.,CAS Institute of Electrical Engineering | And 2 more authors.
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2012

A dynamic energy dispatch strategy based on frequency bias is presented for the photovoltaic-diesel-energy storage microgrid, which aims at frequency fluctuation caused by the sudden change of load and the characteristic of photovoltaic microsource. According to the frequency bias forming principle of diesel generator and the demand for steady operation and power quality of microgrid, a three-stage dynamic energy dispatch strategy based on proportional-derivative (PD) preceding is achieved, which overcomes the shortcoming of PD strategy. This modified strategy is implemented in the established microgrid system, and two pairs of contrast experiments are made to verify the suppression effect of system frequency fluctuation. The experiments have proved that this strategy for dynamic energy dispatching can mitigate the frequency fluctuation caused by photovoltaic microsource and load sudden change to some extent, thus it is a feasible solution to improving power quality and stability of microgrid. This work is supported by National Natural Science Foundation of China (No. 50777064).


Yang M.,Nanjing University of Aeronautics and Astronautics | Yang M.,Army Aviation Institute of PLA | Huang D.,Nanjing University of Aeronautics and Astronautics
Shiyan Liuti Lixue/Journal of Experiments in Fluid Mechanics | Year: 2011

Some of the unsteady aerodynamic characteristics were analyzed using the wind tunnel test results for a fighter model couple motion at high angle of attack in this paper. The results showed that the aerodynamic characteristics of multi-degree of freedom motion were more complicated than that of single degree of freedom. There were some differences on the aerodynamic characteristics between the test results of coupled motion and the linear superposition results of two single degree of freedom motions. In addition, compared with rotary balance testing, the results of the test in the paper showed a greater difference.


Yang M.,Nanjing University of Aeronautics and Astronautics | Yang M.,Army Aviation Institute of PLA | Huang D.,Nanjing University of Aeronautics and Astronautics
Kongqi Donglixue Xuebao/Acta Aerodynamica Sinica | Year: 2011

The fuzzy logic modeling of rolling moment is established with different modeling variables, based on the wind tunnel test results of large-amplitude yawing motion and rolling motion. The effects of different variables on the model precision are analyzed. Using reasonable variables obtained from above, the unsteady aerodynamic model of yawing-rolling coupled-motion is set up by means of the fuzzy logic, and the aerodynamic coefficients are acquired. Comparing calculation results with test results, the influence of model accuracy by variables of different combination is investigated. In spite of any motion forms, the relationship between variables is the main factor that influences the model precision. Considering single freedom motion, α, β, ωy(ωx) should be selected as modeling variables; likewise, α, β, ωx, ωy regarded as modeling variables are better than others for coupled-motion.


Wen S.W.,National University of Defense Technology | Xiao J.Y.,National University of Defense Technology | Wang Y.R.,Army Aviation Institute of PLA
Composites Part B: Engineering | Year: 2013

The present study investigated the salt fog effect on the quasi-static tensile and fatigue properties of the center-cracked aluminum plates which were single-sidedly repaired with C f/epoxy composite patches. The results show that the salt fog has minimal impact on the quasi-static tensile properties of the epoxy resin and C f/epoxy composites; while the quasi-static tensile and fatigue properties of the repaired and unrepaired specimens all decrease with the exposure time of the salt fog increasing. Compared to the unrepaired specimens, the repaired specimens have high resistance to salt fog degradation. Within the 0-900 h range of exposure time, the repaired specimens completely fail when the fatigue crack length is equal to the width of the aluminum plate. However, as the exposure time is larger than 900 h, the repaired specimens can still bear fatigue loading when the fatigue crack propagates through the aluminum plate. © 2012 Published by Elsevier Ltd.

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