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All-Electric Aircraft Nose Wheel Steering System with Two Worm Gears

Transactions of Nanjing University of Aeronautics and Astronautics 2018年第1期35卷 170-180页

作者： Zhang Ming Li Chuang Wu Xin Zhu Yin Key Laboratory of Fundamental Science for National Defense-Advanced Design Technology of Flight Vehicle Nanjing University of Aeronautics&AstronauticsNanjing 210016P.R.China Shanghai Aircraft Design and Research Institute Shanghai 201210P.R.China Aviation Key Laboratory of Science and Technology on Aero Electromechanical System Integration Nanjing 211106P.R.China

As all-electric aircraft has many advantages,an aircraft nose wheel steering system would be developed to the all-electric *** the control demand of the nose wheel steering system,based on the basic principles of nose wheel steering system and the design technique of mechanotronics,an all-electric aircraft nose wheel steering system,composed of a nose wheel steering mechanism of two worm gear and a control servo system of fly-by-wire with both steering and anti-shimmy functions is designed to meet the demand for operation control in the nose wheel steering ***,based on the LMS-AMESim software,the simulation model of the system is established to simulate the dynamics for the verification of its steering *** simulation results indicate that the nose wheel steering system is reasonable,and can meet the requirements of the general ***,the prototypes of the steering mechanism and control system are studied to validate the design,and the steering test bench is prepared to test the designed *** test results,such as steer angle,rotate speed of motor are analyzed in details and compared with the theoretical *** analysis and comparison results show that the design is reasonable and the property of the prototype can achieve the design objectives.

关键词： mechanotronics design nose wheel steering system all-electric aircraft design landing gear

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Daily CO_(2) Emission Reduction Indicates the control of Activities to Contain COVID-19 in China

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The Innovation 2020年第3期1卷 24-36页

作者： Rong Wang Yuankang Xiong Xiaofan Xing Ruipu Yang Jiarong Li Yijing Wang Junji Cao Yves Balkanski Josep Peñuelas Philippe Ciais Didier Hauglustaine Jordi Sardans Jianmin Chen Jianmin Ma Tang Xu Haidong Kan Yan Zhang Tomohiro Oda Lidia Morawska Renhe Zhang Shu Tao Department of Environmental Science and Engineering Fudan UniversityShanghai 200438P.R.China Institute of Atmospheric Sciences Fudan UniversityShanghai 200438P.R.China Big Data Institute for Carbon Emission and Environmental Pollution Fudan UniversityShanghai 200438P.R.China Key Laboratory of Aerosol Chemistry and Physics Institute of Earth EnvironmentChinese Academy of SciencesXi'an 710075P.R.China Laboratoire des Sciences du Climat et de l’Environnement CEA CNRS UVSQ91190 Gif-sur-YvetteFrance CREAF Cerdanyola del Vallès08193 CataloniaSpain CSIC Global Ecology Unit CREAF-CSIC-UABBellaterra08193 CataloniaSpain College of Urban and Environmental Sciences Laboratory for Earth Surface ProcessesPeking University100871 BeijingP.R.China School of Public Health Key Laboratory of Public Health Safety of the Ministry of Education and National Health Commission Key Laboratory of Health Technology AssessmentFudan UniversityShanghai 200438P.R.China Universities Space Research Association ColumbiaMDUSA Global Modeling and Assimilation Office NASA Goddard Space Flight CenterGreenbeltMDUSA Queensland University of Technology 2 George StreetBrisbaneQLD 4001Australia Shanghai Institute of Pollution Control and Ecological Security Shanghai 200092P.R.China

Lockdown measures are essential to containing the spread of coronavirus disease 2019(COVID-19),but they will slow down economic growth by reducing industrial and commercial ***,the benefits of activity control from containing the pandemic have not been examined and *** we use daily carbon dioxide(CO_(2))emission reduction in China estimated from statistical data for energy consumption and satellite data for nitrogen dioxide(NO_(2))measured by the Ozone Monitoring Instrument(OMI)as an indicator for reduced activities consecutive to a *** perform a correlation analysis to show that a 1%day-1 decrease in the rate of COVID-19 cases is associated with a reduction in daily CO_(2) emissions of 0.22%±0.02%using statistical data for energy consumption relative to emissions without COVID-19,or 0.20%±0.02%using satellite data for atmospheric column NO_(2).We estimate that swift action in China is effective in limiting the number of COVID-19 cases<100,000 with a reduction in CO_(2) emissions of up to 23%by the end of February 2020,whereas a 1-week delay would have required greater containment and a doubling of the emission reduction to meet the same *** analyzing the costs of health care and fatalities,we find that the benefits on public health due to reduced activities in China are 10-fold larger than the loss of gross domestic *** findings suggest an unprecedentedly high cost of maintaining activities and CO_(2) emissions during the COVID-19 pandemic and stress substantial benefits of containment in public health by taking early actions to reduce activities during the outbreak of COVID-19.

关键词： COVID-19 PANDEMIC CARBON EMISSION ENERGY CONSUMPTION SOCIAL CARBON COST CONTAINMENT EFFICACY PUBLIC HEALTH CORRELATION ANALYSIS INTEGRATED MODEL

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A Planar Ring Cavity ZnGeP2 Optical Parametric Oscillator Cascade Pumped by 2μm Tm-Ho Laser

A Planar Ring Cavity ZnGeP2 Optical Parametric Oscillator Ca...

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2019 2nd International Conference on Mechanical Engineering,Industrial Materials and Industrial Electronics(MEIMIE 2019)

作者： Jingliang Liu Xinyu Chen Hui Wang Guangyong Jin Jilin Key Laboratory of Solid Laser Technology and Apply School of ScienceChangchun University of Science and Technology Air Traffic Control and Navigation Teaching and Research Section School of Operation and ServiceAviation University of Air Force

3-5μm mid-infrared lasers have applications in several domains including spectrum detection, environmental monitoring, and medical diagnosis and optoelectronic countermeasures. The ZnGeP optical parametric oscillator(OPO) pumped by 2μm laser is the important device for wavelength conversion into the 3-5μm mid-infrared waveband. A planar ring cavity ZnGeP OPO cascade pumped by 2μm Tm-Ho laser was reported in this paper. When the pulse Tm-Ho laser pump power of 15 W, the maximum output power of the ZnGeP OPO laser was 4.12 W, corresponding to the optical-optical conversion efficiency and the slope efficiency were 27.5% and 36.2%, respectively. The output peak wavelength is 3.9μm and 4.5μm, the pulse width is 17.5 ns, and the beam quality is M2≈2.8.

关键词： Planar ring cavity ZnGeP2 Optical parametric oscillator

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Numerical investigation of influence of structure and operating parameters on performance of vortex oil filter

Numerical investigation of influence of structure and operat...

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CSAA/IET International Conference on Aircraft Utility Systems, AUS 2018

作者： Wang, Ning Chen, Weijian Ning, Guoli Hui, Ma Key Laboratory of Aircraft Environment Control and Life Support MIIT Nanjing University of Aeronautics and Astronautics Nanjing China Aviation Key Laboratory of Science and Technology on Aero Electromechanical System Integration Nanjing China

ISBN: (纸本)9781785617911

In this paper, the three-dimensional numerical simulation of solid-liquid two-phase flow in a vortex oil filter is performed by means of numerical simulation. The Reynolds stress turbulence model is used in the simulation flow field, and the DPM model is used for solid particle tracking. The influence of key structural parameters and operating parameters on the filtering effect was mainly studied, such as the inlet width, the size of the overflow pipe, the wall thickness and the insertion depth, the size of the cone angle and the length of the cone end. The results provide the basis for the rational design of the vortex oil filter. © 2018 IET Conference Publications. All rights reserved.

关键词： Vortex flow

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Remaining useful life prediction based on variation coefficient consistency test of a Wiener process

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Chinese Journal of Aeronautics 2018年第1期31卷 107-116页

作者： Juan LI Bo JING Hongde DAI Xiaoxuan JIAO Xiaodong LIU College of Aeronautics and Astronautics Engineering Air Force Engineering University Xi'an 710038 China College of Mathematics and Statistics Ludong University Yantai 264025China Department of Control Engineering Naval Aeronautical and Astronautical University Yantai 264001 China China Aviation Industry Jincheng Nanjing Electrical and Hydraulic Engineering Research Center Nanjing 210000 China Aviation Science and Technology Key Laboratory of Aviation Mechanical and Electrical System Nanjing 210000 China

High-cost equipment is often reused after maintenance, and whether the information before the maintenance can be used for the Remaining Useful Life （RUL） prediction after the maintenance is directly determined by the consistency of the degradation pattern before and after the maintenance. Aiming at this problem, an RUL prediction method based on the consistency test of a Wiener process is proposed. Firstly, the parameters of the Wiener process estimated by Maximum Likelihood Estimation （MLE） are proved to be biased, and a modified unbiased estimation method is proposed and verified by derivation and simulations. Then, the h statistic is constructed according to the reciprocal of the variation coefficient of the Wiener process, and the sampling distribution is derived. Meanwhile, a universal method for the consistency test is proposed based on the sampling distribution theorem, which is verified by simulation data and classical crack degradation data. Finally, based on the consistency test of the degradation model, a weighted fusion RUL prediction method is presented for the fuel pump of an airplane, and the validity of the presented method is verified by accurate computation results of real data, which provides a theoretical and practical guidance for engineers to predict the RUL of equipment after maintenance.

关键词： Degradation Fuel pumps Prognostic and health management Remaining useful life （RUL） Wiener processes

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Tensor Completion based 3D Reconstruction of Binocular Stereo Vision

Tensor Completion based 3D Reconstruction of Binocular Stere...

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IEEE International Conference on Industrial Engineering and Engineering Management

作者： Ze-Hua Liu Hai-Jun Rong Zhao-Xu Yang Zhi-Xin Yang State Key Laboratory for Strength and Vibration of Mechanical Structures Shaanxi Key Laboratory of Environment and Control for Flight Vehicle School of Aerospace Xi'an Jiao tong University Shaanxi China State Key Laboratory of Internet of Things for Smart City Faculty of Science and Technology University of Macau Macao

Binocular stereo vision is a common way for 3D reconstruction of objects, which is core technology in the fields of computer-aided geometric design, machine vision and so on. However, the conventional binocular stereo vision algorithms are very sensitive to the ambient lighting, restricting their further promotion. The method of tensor completion, applied to the progress of preprocessing the captured binocular image, provides a way to solve this problem. In this paper, a binocular stereo vision algorithm that uses low-rank tensor completion to perform 3D reconstruction is presented. In the pictures, the positions where the ambient illumination are strong are regarded as information that cannot be observed, and the others are regarded as observable information. The unobservable information will be completed using the observable information based on tensor completion. The results show that the 3D reconstruction results obtained using tensor completion are better than those without tensor completion.

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Fault Characteristics Analysis of Planetary Gear of Helicopter Main Reducer

Fault Characteristics Analysis of Planetary Gear of Helicopt...

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Prognostics and System Health Management Conference (PHM-Qingdao)

作者： Liang Cao Yubin Xia Yong Shen Jinglin Wang Tianmin Shan Zeli Lin Aviation Key Laboratory of Science and Technology on Fault Diagnosis and Health Management AVIC Shanghai Aero Measurement-Controlling Research Institute Shanghai China State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and Astronautics Nanjing China

According to the characteristics of the large transmission ratio of the helicopter main reducer in the future, the research on the characteristic distribution of the planetary gear train of the helicopter main reducer is carried out. Because of the characteristics that the heavy load condition in helicopter main reducer's running and the changeable running state and complex and harsh climatic conditions and the increasing heat of the flow field in the reducer, by the way, the large transmission ratio increases the uncertainty of the planetary gear train operation analysis at the same time, the probability of causing a failure is greater; Especially the complex and variable structure of the helicopter which has large transmission ratio main reducer makes the analysis difficulty further. For ensuring the safety and enhancing the reliability of the helicopter, this paper make a comparative analysis of the time domain characteristics of the state signals under the multi-operating condition between the normal planetary gear and planetary gears with different degrees of failure, to explore the distribution regularity of the fault characteristics of the helicopter main reducer, so as to realize the research on fault diagnosis of helicopter large transmission ratio planetary gear.

关键词： Heating systems Fault diagnosis Uncertainty Gears Helicopters Safety Time-domain analysis

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Positioning Method of Chang'E-4 lander based on Multi-source Images 69

Positioning Method of Chang'E-4 lander based on Multi-source...

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69th International Astronautical Congress: #InvolvingEveryone, IAC 2018

作者： Wang, Jia Peng, Man Wan, Wenhui Zhou, Zhanyong Rong, Zhifei Wang, Baofeng Ma, Weihua Lu, Xinyuan He, Ximing You, Yi Beijing Aerospace Control Center National Key Laboratory of Science and Technology on Areospace Flight Dynamics100094 China State Key Laboratory of Remote Sensing Science Institute of Remote Sensing and Digital Earth Chinese Academy of Sciences Beijing China National Key Laboratory of Areospace Flight Dynamics 127West Youyi Road Xi'an7100072 China

The Chang'E-4 lunar probe will land on the lunar farside for the first time at the end of 2018. Fast and high precision positioning of the landing point is essential for safe and efficient mission execution. In this paper, we proposed a method for positioning of Chang'E-4 lander based on multi-source images including descent images, Lunar Reconnaissance Orbiter Camera (LROC) Narrow Angle Camera (NAC) images, and landing zone Digital Orthophoto Map (DOM). First, several descent images were selected from sequence images. The selected images are subsequently matched with Scale Invariant Feature Transform matching, during which gross errors are eliminated by a Random Sample Consensus algorithm. All matched feature points are used to calculate the parameter of a similarity transformation model between the initial image and the last image using the least-squares principle. The image coordinates of the landing position at the initial image are solved. Second, the initial image is matched with the landing zone DOM. Consequently, the preliminary landing position can be determined. Third, all LRO NAC images that cover the preliminary landing position are retrieved. Feature point matching is performed between initial image and each LRO NAC image to calculate the transformation relationship between them. Image coordinates of the landing position in each LRO NAC image can then be calculated based on the coordinates in the initial image and the transformation parameters. Finally, multiple observations are averaged as the final position result with a consideration of the existence of random errors, e.g. errors of track measurement and control, image matching and lunar elevation. With LROC NAC images used which are of the highest resolution, feature point matching can achieve high accuracy. Furthermore, the speed and precision of determining the landing point can be improved. Landing position experiment was performed for Chang'E-3. The descent images were selected from the power de

关键词： Cameras

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Network Resilience

arXiv

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arXiv 2020年

作者： Liu, Xueming Li, Daqing Ma, Manqing Szymanski, Boleslaw K. Eugene Stanley, H. Gao, Jianxi Key Laboratory of Image Information Processing and Intelligent Control School of Artificial Intelligence and Automation Huazhong University of Science and Technology Hubei Wuhan430074 China School of Reliability and Systems Engineering Beihang University Beijing100191 China College of Safety Science and Engineering Civil Aviation University of China Tianjin 300300 China Department of Computer Science Rensselaer Polytechnic Institute TroyNY12180 United States Network Science and Technology Center Rensselaer Polytechnic Institute TroyNY12180 United States Center for Polymer Studies Department of Physics Boston University BostonMA02215 United States

Many systems on our planet shift abruptly and irreversibly from the desired state to an undesired state when forced across a "tipping point". Some examples are mass extinctions within ecosystems, cascading failures in infrastructure systems, and changes in human and animal social networks. The ability to avoid such regime shifts or to recover quickly from such a non-resilient state demonstrates a system's resilience;system resilience is a quality that enables a system to adjust its activities to retain its basic functionality when errors and failures occur. In the past 50 years, attention has been paid almost exclusively to low-dimensional systems;scholars have focused on the calibration of the resilience functions of such systems and the identification of indicators of early warning signals based on two to three connected components. In recent years, taking advantage of network theory and the availability of lavish real datasets, network scientists have begun to explore real-world complex networked multidimensional systems, as well as their resilience functions and early warning indicators. This report presents a comprehensive review of resilience functions and regime shifts in complex systems in domains such as ecology, biology, society, and infrastructure. The research approach includes empirical observations, experimental studies, mathematical modeling, and theoretical analysis. We also review the definitions of some ambiguous terms, including robustness, resilience, and stability. Copyright © 2020, The Authors. All rights reserved.

关键词： Complex networks

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The Design of a High Precision Capacitive Pressure Sensor Based on Comb Electrode

The Design of a High Precision Capacitive Pressure Sensor Ba...

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Progress in Electromagnetics Research Symposium - Fall (PIERS - FALL)

作者： Xuejiao Li Libo Zhao Xiangguang Han Ping Yang Guoxi Luo Nan Zhu Zhikang Li Songli Wang Xin Yan Zhuangde Jiang State Key Laboratory for Manufacturing Systems Engineering International Joint Laboratory for Micro/Nano Manufacturing and Measurement Technologies Collaborative Innovation Center of Suzhou Nano Science and Technology Xi’an Jiaotong University Xi’an China Flight Automatic and Control Institute Xi’an China

ISBN: (数字)9781728153049

ISBN: (纸本)9781728153056

MEMS capacitive sensors promise wide applications in the field of high precision pressure sensing because of their low temperature drift, low power consumption and high precision. Based on the deformation principle of diaphragm under pressure, we present the design and fabrication process of a novel high precision MEMS capacitive pressure sensor, which consists of island-diaphragm composited structure and comb electrode. Furthermore, a finite element simulation analysis is conducted to demonstrate the excellent performance of the sensor. The simulation results show that the capacitance output non-linearity in load pressure range of 75-125 kPa and 125-200 kPa are 0.083%FS and 0.074%FS, with the sensitivities of 9.3 fF/kPa and 10.6 fF/kPa, respectively.

关键词： Electrodes Pressure sensors Strain Capacitance Silicon Simulation Micromechanical devices

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