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IEEE International Conference on Aircraft Utility Systems (AUS)

作者： Chao Hu Pengfei Zhang Xiaoping Ouyang Houtao Ku Qinghe Zhou Enxiao Zhang State Key Lab. of Fluid Power Transmission and Control Zhejiang University Hangzhou China Aviation Key Laboratory of Science and Technology on Aero Electromechanical System Integration Nanjing China The High School Attached to Zhejiang University Hangzhou China

ISBN: (纸本)9781509010882

Seal is one of the most important characteristics for cylinders and suitable seal configuration will guarantee the long life cycle of the seal and the cylinder. Experiment is the only way which can demonstrate the best seal configuration in applications. In this paper, one approach is brought forward for testing the seal performance of cylinders with different seals configurations at the same load working condition for saving the test time. In the test-rig, the synchronization of cylinders is one of the key technologies. The test system is modelled in the AMESim software. The effect caused by the changes of the different physical parameters is analyzed, such as load stiffness, viscous damping coefficient of cylinder, dead volume of cylinder and internal leakage coefficient. The experiment is carried out and test results agree with the simulation results. Finally, the appropriate solution is proposed for improving the synchronization of the multi-cylinders further.

关键词： Synchronization Valves Seals Damping Load modeling Springs Servomotors

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Characterizations of thin tungsten films deposited on polyimide, Si(111) and SiO2by direct-current magnetron sputtering

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Journal of Computational and Theoretical Nanoscience 2016年第9期13卷 5660-5663页

作者： Zhang, Rui Liu, Yujia Wang, Yan Huo, Zhenxuan Du, Bo Zhong, Hui Shi, Yu State Key Laboratory of Electronic Thin Films and Integrated Devices University of Electronic Science and Technology of China Chengdu610054 China Civil Aviation Flight University of China Guang Han618307 China 26th Institute of China Electronics Technology Group Corporation Nan An District Chongqing40060 China

Thin tungsten films have been widely used in silicon-based electronics and flexible electronics. They are usually deposited either on rigid or flexible substrates. The structure of tungsten films directly influences the performance of tungsten-based devices, whereas the characteristics of tungsten films are inversely influenced by substrate materials. In this study, effects of commonly used rigid substrates of Si(111), SiO2and flexible substrates of polyimide on properties of tungsten films deposited by direct-current magnetron sputtering were investigated. It was found that tungsten films on the three substrates all exhibited mixed phases. On SiO2and polyimide substrates the α-tungsten with (110) texture was enhanced. Growth of tungsten grains was also facilitated on SiO2and on polyimide substrates. Tungsten films on SiO2had the roughest surface. While tungsten films sputtered on Si(111) exhibited flat surface with the smallest surface roughness. Column-like microstructure of tungsten films were presented on polyimide substrates with relatively low electrical resistivity and deposition rate. Tungsten films sputtered on Si(111) demonstrated porous microstructure showing the highest deposition rate and electrical resistivity. While tungsten films deposited on SiO2had dense and tightly compact microstructure with lowest electrical resistivity and deposition rate. Based on this study, tungsten films deposited on polyimide substrates demonstrate competitive qualities comparing with which deposited on SiO2and Si(111). To take advantage of flexibility the commonly used rigid substrates of Si(111) and SiO2can be replaced by flexible polyimide substrates in designing and fabricating tungsten-based devices. Copyright © 2016 American Scientific Publishers All rights reserved.

关键词： Microstructure

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Single moving-mass asymmetrical reentry vehicle guidance law design 34

Single moving-mass asymmetrical reentry vehicle guidance law...

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第三十四届中国控制会议

作者： WANG Lin-lin YU Jian-qiao JING Wen-ming SU Xiao-long Key Laboratory of Dynamics and Control of Flight Vehicle Ministry of EducationSchool of Aerospace Engineering Beijing Institute of Technology Ordnance Science Institute of China

ISBN: (纸本)9789881563897

By analyzing predictor-corrector method, a modified guidance law is designed for single moving-mass asymmetrical reentry *** could guarantee a relatively high precision while the requirements for computational efficiency of calculator in the vehicle is low. Principles of the predictor-corrector method are analyzed in detailed and the problems which need to be solved when applied to the asymmetrical reentry vehicle are indicated. A modified strategy is put forward to deal with the problems. When the altitude of the trajectory is relatively high, the predictor-corrector method is adopted and the constraints of the precision in the end of the predictor-corrector part of the whole trajectory are relaxed. When parameter Ω>1, the modified method can be adopted for the end of the whole trajectory. The simulation results show that the modified guidance law could satisfy the constraints of computational efficiency and guarantee a high precision at the same time.

关键词： reentry guidance law asymmetrical reentry vehicle predictor-corrector moving-mass control

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Vibration diagnostic method based on improved intrinsic time-scale decomposition and energy operator demodulation for fault diagnosis of helicopter planetary gearboxes

Vibration diagnostic method based on improved intrinsic time...

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Prognostics and System Health Management Conference (PHM)

作者： Canfei Sun Youren Wang Yan Zhang College of Automation Engineering Aviation Key Laboratory of Science and Technology on Fault Diagnosis and Health Management Nanjing China College of Automation Engineering Nanjing University of Aeronautics and Astronautics Nanjing China Research Center Shanghai Aero Measurement & Control Technology Research Institute Shanghai China

ISBN: (纸本)9781509027798

Planetary gearboxes play a significant role in helicopter transmission system. Fault diagnosis of planetary gearboxes is a key topic for health monitoring and maintenance of helicopter. The vibration signals of faulty planetary gearboxes have complicated spectral structures due to its distinctive and complex structure and time-variant running operation condition, leading to the difficulty in fault diagnosis of planetary gearboxes. Considering that both the amplitude envelope and the instantaneous frequency of vibration signals are associated with the characteristic frequency of the faulty gear, we propose a vibration diagnostic method using the amplitude and frequency demodulation analysis. First, the vibration signal was decomposed into several proper rotation components (PRs) and a trend component by the improved intrinsic time-scale decomposition (IITD) method. Then the energy operator method was exploited to estimate the amplitude envelope and instantaneous frequency of the PR which contained obvious impacts. Finally, by analyzing the dominant peaks in the Fourier spectra of the demodulated amplitude envelope and instantaneous frequency with the theoretical characteristic frequency of each gear, we can diagnose planetary gearbox faults. The effectiveness of the proposed method is demonstrated by simulated signal analysis, and is validated by experimental signal analysis of a lab planetary gearbox with sun gear faults including a chipped tooth and a missing tooth.

关键词： Gears Frequency modulation Sun Vibrations Helicopters Demodulation Fault diagnosis

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Study on subjective statement screening of product reviews based on the feature combination method

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ICIC Express Letters 2016年第7期10卷 1591-1597页

作者： Sun, Tieli Guan, Weiqiao Yang, Fengqin Sun, Hongguang Ji, Chuande Song, Meijia Li, Yanwen School of Computer Science and Information Technology Northeast Normal University No. 2555 Jingyue Ave Changchun130117 China Key Laboratory of Intelligent Information Processing of Jilin Universities No. 2555 Jingyue Ave Changchun130117 China Flight Theory Department Aviation University of Air Force Changchun130022 China

Subjective statement screening is a fundamental part of sentiment analysis of product reviews. Its aim is to extract the subjective texts from product reviews and filter objective texts that do not contain any sentimental information. The existing screening methods are mainly based on only one feature. However, single feature is insufficient to mark all subjective or objective statements. We propose a feature combination method based on the N-pos feature, the word feature and the syntactic dependency feature for subjective statement screening. The experiments on the real datasets show that the proposed feature combination method significantly improves the accuracy of subjective statement screening and is really feasible and effective. © 2016, ICIC Express Letters Office. All rights reserved.

关键词： Sentiment analysis

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Spin-Filtering Transport in Double Parallel Quantum Wires on a Graphene Sheet

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Communications in Theoretical Physics 2015年第3期63卷 385-390页

作者：羊富彬程艳柳福提陈向荣蔡灵仓 Institute of Atomic and Molecular Physics College of Physical Science and TechnologySichuan University Department of Physics College of ComputerCivil Aviation Flight University of China School of Electrical Computer and Energy EngineeringArizona State University Key Laboratory of High Energy Density Physics and Technology of Ministry of Education Sichuan University Institute of Fluid Physics Chinese Academy of Engineering Physics

We theoretically investigate the spin filtering transport of double parallel quantum wires(QWs) side-coupled to a grapheme sheet and sandwiched between two ferromagnetic(FM) *** dependences of the wire-graphene coupling strength,wire-wire coupling strength,as well as the spin polarization of the ferromagnetic leads are *** is found that the wire-graphene coupling strength tends to reduce the current and the wire-wire coupling strength can first reinforce and then decrease the *** spin polarization strength has an enhanced(identical) effect on the current under the parallel(anti-parallel) alignment of the FM leads,which gives rise to an obvious spin-filter and tunnel magnetoresistance(TMR) *** results suggest that such a theoretical model can stimulate some experimental investigations about the spin-filter devices.

关键词： spin-filter effect double parallel quantum wires spin polarization strength graphene

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A novel matching method of large deformed images for localizing lunar rovers with large distance 1 66

A novel matching method of large deformed images for localiz...

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66th International Astronautical Congress 2015: Space - The Gateway for Mankind's Future, IAC 2015

作者： Liu, Chuankai Wang, Baofeng Su, Jianhua Wang, Jia Tang, Geshi Zhang, Yuren Wang, Xiaoxue Yang, Yongfang Beijing Aerospace Flight Control Center Beijing100094 China Key Laboratory of Science and Technology on Aerospace Flight Dynamics Beijing100094 China Institute of Automation Chinese Academy of Sciences Beijing100190 China Jiuquan Satellite Launch Center Jiuquan735000 China

ISBN: (纸本)9781510818934

In the Lunar Exploration, one important mission of the ground teleoperation center is estimating the position of each navigation station that the rover reaches, which facilitates the rover to gradually approach and finally get to the scientific probing targets. Accurate rover positioning is usually achieved in two steps. First, the inertial navigation information is used to roughly estimate the position of the rover in the current station, and then vision-based positioning method, taking the inaccurate result as an initial input, is used to calculate the rover position with a high accuracy. Currently, the most perspective vision-based high-accuracy positioning methods are implemented with multi-camera photogrammetric model, which takes the homonymous points extracted from camera images as the intersection points of camera bundles to establish observation equations. The amount, spatial distribution and matching accuracy of homonymous points will affect the positioning accuracy of the rover. In the case of large-span moving, the images acquired by rover in two navigation stations with a fairly big distance are difficult to be matched due to the existence of large scale and rotation transformations, reflected view of the same scenery, and different illumination conditions between acquired images. Traditional appearance matching algorithms, like SIFT and its derived methods, often fail in handling the above situations. Some improved appearance matching algorithms, which take the afftne transformation of images into account, such as affine SIFT, perform better than traditional ones in handling large-scale transformation problem, but they are still not able to obtain satisfactory results in tackling the above situations. In this paper, we proposed a novel matching method, which first utilizes the imaging relation contained in the large-span moving of the rover to simulate the approximate geometric transformation between large- deformed images, and then takes approximate t

关键词： Mathematical transformations

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Monitoring CE’3 Rover movement using same-beam interferometry with china’s deep space network

Lecture Notes in Electrical Engineering

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Lecture Notes in Electrical Engineering 2015年 334卷 651-659页

作者： Han, Songtao Tang, Geishi Cao, Jianfeng Chen, Lue Ren, Tianpeng National Key Laboratory of Science and Technology on Aerospace Flight Dynamics Beijing Aerospace Control Center Beijing100094 China

China’s Deep Space Network (DSN) was deployed in 2013, a high-accuracy interferometric tracking observable was successfully used for orbit determination in the CE’3 project. This chapter presents the results of the rover’s status monitoring by earth-based same-beam interferometry (SBI) measurement. Phase delay with a biased offset is induced to identify the rover’s movement status, which could be up to three orders of magnitude better than conventional group delay. Based on the tracking data within China’s DSN, the status of the rover including going ahead, turning over, and changing signal can be successfully identified with a higher resolution. Combined with baseline length within China’s DSN, the movement of the rover in the order of centimeters can be identified, which testifies the effectiveness of this technique and algorithm. © Springer International Publishing Switzerland 2015.

关键词： Orbits

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A Robust Kalman Filter for Mars Entry Navigation

A Robust Kalman Filter for Mars Entry Navigation

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第三十四届中国控制会议

作者： Zhengshi Yu Shengying Zhu Pingyuan Cui Lina Wang Beijing Institute of Technology Key Laboratory of Dynamics and Control of Flight Vehicle Ministry of Education Beijing Aerospace Automatic Control Institute National Key Laboratory of Science and Technology on Aerospace Intelligence Control

ISBN: (纸本)9781467374439

In this paper?a robust Kalman filter is proposed for Mars entry navigation. The multiple uncertainties present in the Mars atmosphere density together with the unmodeled measurement noise?which may cause the divergence of traditional extended Kalman filter?are mainly considered. In order to improve the robustness of traditional Kalman filter?the relationship between estimation error and the Mars atmosphere density uncertainty and unmodeled measurement noise is derived. Besides the trace of posterior variance matrix?the transition matrices of atmosphere density uncertainty and unmodeled measurement noise are considered to establish the performance index. Next?the optimal Kalman gain matrix is determined by minimizing this performance index. Navigation scenario using range measurements from Mars ground beacons demonstrates the improved accuracy of the proposed robust Kalman filter. Furthermore?the contribution of the coefficients which are corresponding to atmosphere density uncertainty and unmodeled measurement noise to the navigation performance are analyzed. The optimal values of these coefficients are also recommended.

关键词： Extended Kalman filter Mars entry navigation sensitivity

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A vision-based navigation approach with multiple radial shape marks for indoor aircraft locating

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Chinese Journal of Aeronautics 2014年第1期27卷 76-84页

作者： Zhou Haoyin Zhang Tao Department of Automation School of Information Science and TechnologyTsinghua University National Key Laboratory of Integrated Flight Vehicle Control Technology Xi'an Flight Automatic Control Research Institute

Since GPS signals are unavailable for indoor navigation, current research mainly focuses on vision-based locating with a single mark. An obvious disadvantage with this approach is that locating will fail when the mark cannot be seen. The use of multiple marks can solve this problem. However, the extra process to design and identify different marks will significantly increase system complexity. In this paper, a novel vision-based locating method is proposed by using marks with feature points arranged in a radial shape. The feature points of the marks consist of inner points and outer points. The positions of the inner points are the same in all marks, while the positions of the outer points are different in different marks. Unlike traditional camera locating methods （the PnP methods）, the proposed method can calculate the camera location and the positions of the outer points simultaneously. Then the calculation results of the positions of the outer points are used to identify the mark. This method can make navigation with multiple marks more efficient. Simulations and real world experiments are carried out, and their results show that the proposed method is fast, accurate and robust to noise.

关键词： Flexible mark Indoor aircraft Multiple marks Navigation Vision-based locating

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