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2019 5th International Conference on Applied Materials and Manufacturing technology, ICAMMT 2019

作者： Xie, Zongwu Gong, Pixu Liang, Mengde Zhang, Qi Liu, Hong State Key Laboratory of Robotics and System Harbin Institute of Technology Heilongjiang Province Harbin150001 China

For the mission of detumbling and despinning the space debris, like defunct satellites, it is highly reliable and safe to use the permanent magnetic array device (PMAD). Based on the electromagnetic principle, the target's attitude dynamics is analysed, the electromagnetic torque is studied, the formula of electromagnetic force is simplified, and the stability of the nutation Angle is obtained. The rotation speed and attitude of PMAD are controlled by a dual-manipulator space robot to ensure that the component of the torque on the spin axis is zero. So the target will be only affected by the transverse component of the torque, and then the nutation angle decreases gradually to zero. When mission completed, the dual-manipulator space robot can deorbit or maintain on-orbit servicing, which is a significant exploration. © Published under licence by IOP Publishing Ltd.

关键词： Space debris

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High-responsivity solar-blind photodetector based on MOCVD-grown Si-dopedβ-Ga_(2)O_(3)thin film

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Chinese Physics B 2021年第5期30卷 595-601页

作者： Yu-Song Zhi Wei-Yu Jiang Zeng Liu Yuan-Yuan Liu Xu-Long Chu Jia-Hang Liu Shan Li Zu-Yong Yan Yue-Hui Wang Pei-Gang Li Zhen-Ping Wu Wei-Hua Tang Laboratory of Information Functional Materials and Devices School of Science&State Key Laboratory of Information Photonics and Optical CommunicationsBeijing University of Posts and TelecommunicationsBeijing 100876China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China The Engineering Research Center for Semiconductor Integrated Technology Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China China Aerospace System Simulation Technology Co. Ltd.(Beijing)Beijing 100195China College of Electronic and Optical Engineering&College of Microelectronics Nanjing University of Posts and TelecommunicationsNanjing 210023China

Si-dopedβ-Ga_(2)O_(3)films are fabricated through metal-organic chemical vapor deposition(MOCVD).Solar-blind ultraviolet(UV)photodetector(PD)based on the films is fabricated by standard photolithography,and the photodetection properties are *** results show that the photocurrent increases to 11.2 mA under 200μW·cm^(-2)254 nm illumination and±20 V bias,leading to photo-responsivity as high as 788 A·W^(-1).The Si-dopedβ-Ga2O3-based PD is promised to perform solar-blind photodetection with high performance.

关键词： Si-dopedβ-Ga_(2)O_(3) metal-organic chemical vapor deposition(MOCVD) solar-blind high responsivity

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Control of the two-wheeled inverted pendulum (TWIP) robot moving on the continuous uneven ground

Control of the two-wheeled inverted pendulum (TWIP) robot mo...

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2019 IEEE International Conference on robotics and Biomimetics, ROBIO 2019

作者： Zhou, Haitao Li, Xu Feng, Haibo Li, Enbo Ding, Pengchao Zhai, Yanwu Zhang, Songyuan Fu, Yili Harbin Institute of Technology State Key Laboratory of Robotics and System Harbin Heilongjiang Province150001 China

ISBN: (纸本)9781728163215

Uneven terrain is common in natural environment. The TWIP robot has demonstrated its rapid movement ability in even ground in previous works. This paper explores control of the TWIP robot in the continuous uneven ground except the step case. The sinusoidal function and the piece-wise linear function type ground surface are taken as an example to explore motion characteristics of robots on complex terrain. As for the robotic system, continuous or step changes of slope are the main types of disturbance to it. To cope with these disturbance, a Sliding Mode Control (SMC) is used to design the nominal controller due to its insensitivity to uncertainty. Then, the Extended Kalman Filter (EKF) is adopted to estimate the slope of unknown terrain without any ground information from sensors but according to motion state of robot and the Equilibrium Point Estimation (EPE) is then achieved based on the obtained slope angle. In simulation, the TWIP robot moves on these two types of uneven ground surface to track the reference position or velocity trajectory. The comparative experimental results have demonstrated that SMC combined with the EPE method can enable TWIP robot to locomote on some limited uneven ground with higher stability and dynamic performance, compared to the single LQR and the single SMC method. Also, the proposed algorithm has been conduted successfully on the WIP-Bot robot to travel upward and downward slope. © 2019 IEEE.

关键词： Sliding mode control

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Enhancing the Activity And Stability by Coupling Ni-M Bimetals and Tan For Methanol Oxidation Reaction in Alkaline Media

SSRN

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SSRN 2022年

作者： Bai, Yanxin Ye, Na Jiang, Zhao Zhang, Riguang Fang, Tao Shaanxi Key Laboratory of Energy Chemical Process Intensification School of Chemical Engineering and Technology Engineering Research Center of New Energy System Engineering and Equipment Xi’an Jiaotong University Xi’an710049 China State Key Laboratory of Clean and Efficient Coal Utilization Taiyuan University of Technology Taiyuan030000 China

Developing the efficient and durable non-platinum based electrocatalysts for methanol oxidation reaction is critical for the application of direct methanol fuel cells (DMFCs). Here, a series of Ni-based catalysts are synthesized via the microwave-assisted ethylene glycol reduction method, which couples the oxyphile metals with transition metal nitrides (TaN), to study the electrocatalytic behavior for methanol oxidation reaction in alkaline media. The results of transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) indicate that the existence of geometric and electronic effects among Ni, Cu/Sn and TaN. Electrochemical measurements indicate that NiCu-TaN/C and NiSn-TaN/C exhibit high activity with 256.02 and 224.03mA·cm-2, high surface coverage of redox species, abundant active sites, long-term durability and fast reaction kinetics. In situ ATR-SEIRAS results imply that methanol oxidation reaction mainly goes through the direct pathway on the synthesized catalysts. Combined with the structural characterization and electrochemical measurements, it can be found that the enhanced catalytic performance of bimetallic catalysts can be ascribed to the synergistic effect with coupling the oxyphile metals with TaN. The introduction of Cu/Sn and TaN will change the electronic structure of Ni and coverage of Ni(OH)2/NiOOH redox species on the catalyst surface, which modify the adsorption characteristic of reaction intermediates and formation of HCOO, CO2 and OH species following the direct path in alkaline MOR. © 2022, The Authors. All rights reserved.

关键词： Reaction intermediates

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Semantic Geometric Fusion Multi-object Tracking and Lidar Odometry in Dynamic Environment

arXiv

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arXiv 2022年

作者： Ma, Tingchen Ou, Yongsheng The Shenzhen Institute of Advanced Technology Chinese Academy of Sciences Shenzhen518055 China The Shenzhen College of Advanced Technology University of Chinese Academy of Sciences Shenzhen518055 China The Key Laboratory of Human-Machine-Intelligence-Synergy Systems Shenzhen Institute of Advanced Technology Chinese Academy of Sciences Shenzhen518055 China The Guangdong Provincial Key Laboratory of Robotics and Intelligent System Shenzhen Institute of Advanced Technology Chinese Academy of Sciences Shenzhen518055 China

The SLAM system based on static scene assumption will introduce huge estimation errors when moving objects appear in the field of view. This paper proposes a novel multi-object dynamic lidar odometry (MLO) based on semantic object detection technology to solve this problem. The MLO system can provide reliable localization of robot and semantic objects and build long-term static maps in complex dynamic scenes. For ego-motion estimation, we use the environment features that take semantic and geometric consistency constraints into account in the extraction process. The filtering features are robust to semantic movable and unknown dynamic objects. At the same time, a least square estimator using the semantic bounding box and object point cloud is proposed to achieve accurate and stable multi-object tracking between frames. In the mapping module, we further realize dynamic semantic object detection based on the absolute trajectory tracking list (ATTL). Then, static semantic objects and environmental features can be used to eliminate accumulated localization errors and build pure static maps. Experiments on public KITTI data sets show that the proposed system can achieve more accurate and robust tracking of the object and better real-time localization accuracy in complex scenes compared with existing technologies. Copyright © 2022, The Authors. All rights reserved.

关键词： Semantics

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Analysis of Voltage Support Mechanism for Asymmetrical Short-Circuit Faults in Power Electronics-Based systems

Analysis of Voltage Support Mechanism for Asymmetrical Short...

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IEEE Asia Power and Energy Engineering Conference (APEEC)

作者： Shiyu Mo Kun Hu Kui Luo Yiran Jing Liangyi Zhang Erxi Wang School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan China State Key Laboratory of Power Grid and Energy Conservation China Electric Power Research Institute Beijing China Power System Department China Electric Power Research Institute Beijing China State Grid Hubei Electric Power Company Electric Power Research Institute State Grid Hubei Electric Power Company Wuhan China

ISBN: (数字)9798331517540

ISBN: (纸本)9798331517557

With the large-scale integration of renewable energy generation equipment, the transient voltage characteristics of power systems have undergone significant changes. Due to the limited overcurrent capability, renewable energy generation devices have weak transient voltage support. Traditional vector control methods, based on the dq rotating reference frame of individual converters, operate within their respective reference frames and fail to effectively coordinate the overcurrent capabilities of multiple devices. During an asymmetric short-circuit fault, renewable energy devices also control the negative-sequence current, absorbing the negative-sequence current from the AC system to suppress the negative-sequence voltage. In contrast, traditional synchronous generators do not have the ability to control negative-sequence currents. This paper takes a typical single-phase ground fault as an example. It uses the symmetrical components method and composite sequence network. The paper derives the voltage at the renewable energy grid connection point. It also provides expressions and vector relationships for the positive- and negative-sequence components, which are expressed in terms of the positive- and negative-sequence currents. The paper also analyzes the impact of the magnitude and phase of positive- and negative-sequence currents on voltage imbalance and low-voltage ride-through performance, and proposes a new current distribution strategy.

关键词： Renewable energy sources Simulation Power system stability Current distribution Vectors Inverters Synchronous generators Voltage control Transient analysis PSCAD

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Digital light processing three-dimensional printing with acrylic–titanium composite powders for multiscale porous scaffolds

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International Journal of Extreme Manufacturing 2025年第03期 326-341页

作者： Guangbin Zhao Yanlong Wu Bochen Li Hang Tian Bo Li Xiao Li Xu Chen Tao Zhou Yaning Wang Yichao Gong Dingchang Hou Yaxiong Liu Xuewen Zong Bingheng Lu State Key Laboratory for Manufacturing System Engineering School of Mechanical Engineering Xi'an Jiaotong University School of Mechatronic Engineering and Automation Foshan University Ji Hua Laboratory School of Materials Science and Engineering Xi'an University of Technology College of Mechanical Engineering Xi'an University of Science and Technology Mechanical Engineering College Xi'an Shiyou University

Porous metals fabricated via three-dimensional(3D) printing have attracted extensive attention in many fields owing to their open pores and customization potential. However, dense internal structures produced by the powder bed fusion technique fails to meet the feature of porous materials in scenarios that demand large specific surface areas. Herein, we propose a strategy for 3D printing of titanium scaffolds featuring multiscale porous internal structures via powder modification and digital light processing(DLP). After modification, the titanium powders were composited with acrylic resin and maintained spherical shapes. Compared with the raw powder slurries, the modified powder slurries exhibited higher stability and preferable curing characteristics, and the depth sensitivity of the modified powder slurries with 45 vol% solid loading increased by approximately 72%. Green scaffolds were subsequently printed from the slurries with a solid loading reaching 45 vol% via DLP 3D printing. The scaffolds had macropores(pore diameters of approximately 1 mm) and internal open micropores(pore diameters of approximately 5.7–13.0 μm) after sintering. Additionally, these small-featured(approximately 320 μm) scaffolds retained sufficient compressive strength((70.01 ± 3.53) MPa) even with high porosity(approximately 73.95%). This work can facilitate the fabrication of multiscale porous metal scaffolds with high solid loading slurries,offering potential for applications requiring high specific surface area ratios.

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PEBO-SLAM: Observer Design for Visual Inertial SLAM with Convergence Guarantees

arXiv

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arXiv 2023年

作者： Yi, Bowen Jin, Chi Wang, Lei Shi, Guodong Ila, Viorela Manchester, Ian R. The Australian Centre for Robotics School of Aerospace Mechanical and Mechatronic Engineering The University of Sydney SydneyNSW2006 Australia The TuSimple Inc. Liangmaqiao Road Beijing China State Key Laboratory of Industrial Control Technology Institute of Cyber-Systems and Control Zhejiang University Hangzhou310027 China

This paper introduces a new linear parameterization to the problem of visual inertial simultaneous localization and mapping (VI-SLAM)—without any approximation—for the case only using information from a single monocular camera and an inertial measurement unit. In this problem set, the system state evolves on the nonlinear manifold SE(3)×3n, on which we design dynamic extensions carefully to generate invariant foliations, such that the problem can be reformulated into online constant parameter identification, then interestingly with linear regression models obtained. It demonstrates that VI-SLAM can be translated into a linear least squares problem, in the deterministic sense, globally and exactly. Based on this observation, we propose a novel SLAM observer, following the recently established parameter estimation-based observer (PEBO) methodology. A notable merit is that the proposed observer enjoys almost global asymptotic stability, requiring neither persistency of excitation nor uniform complete observability, which, however, are widely adopted in most existing works with provable stability but can hardly be assured in many practical scenarios. © 2023, CC BY.

关键词： Parameter estimation

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Analysis of the Spatiotemporal Changes in Global Land Cover from 2001 to 2020

SSRN

引用

SSRN 2023年

作者： He, Jianjun Jing, Qiaoqiao Li, Yarong Yang, Xianyu Peng, Yue Wang, Hong Yu, Fei Wu, Jie Gong, Sunling Che, Huizheng Zhang, Xiaoye School of Atmospheric Sciences Chengdu University of Information Technology Chengdu610225 China State Key Laboratory of Severe Weather Key Laboratory of Atmospheric Chemistry of CMA Chinese Academy of Meteorological Sciences Beijing100081 China Key Laboratory for Semi-Arid Climate Change The Ministry of Education College of Atmospheric Sciences Lanzhou University Lanzhou730000 China Center for Earth System Modeling and Prediction of CMA Beijing100081 China National Climate Centre Beijing100081 China

Changes in land cover have far-reaching effects on climate change and the evolution of ecological environments, making it an important component of global change research. Based on MODIS land cover data, statistical parameters such as land cover dynamic degree, transition probability, and transition matrix were employed to analyze the spatiotemporal characteristics of global land cover changes from 2001 to 2020. The results indicated that land cover exhibited latitudinal distribution in mid-latitude regions and longitudinal distribution in high-latitude and low-latitude regions. During the study, the areas of evergreen needleleaf forests, deciduous needleleaf forests, deciduous broadleaf forests, closed shrublands, and permanent wetlands have exhibited fluctuating changes. The areas of evergreen broadleaf forests and barren lands have been decreasing annually, while mixed forests, woody savannas, grasslands, urban and built-up areas, cropland/natural vegetation mosaics have been increasing year by year. In terms of dynamics, the most significant changes have occurred in deciduous broadleaf forests, closed shrublands, permanent wetlands, and cropland/natural vegetation mosaics. Furthermore, the changes display distinct regional characteristics. In the mid to high latitude regions, significant changes were observed in evergreen needleleaf forests, grassland types and croplands. In low latitude regions, significant changes were seen in evergreen broadleaf forests and open shrublands. For transforming relationships, various forest vegetation types primarily shifted towards woody savannas. Shrublands, permanent wetlands, and croplands mainly transitioned towards grasslands and savannas. Additionally, land cover transitions exhibit regional disparities. Evergreen needleleaf forests converting into grassland types, as well as conversion between grassland types, were the main transitions in mid to high latitude regions. In tropical areas, evergreen broadleaf forests, open s

关键词： Climate change

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Analysis of Peak Regulation Auxiliary Service Market under the Deepening Stage of the Spot Market Construction 6

Analysis of Peak Regulation Auxiliary Service Market under t...

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6th Asia Conference on Power and Electrical Engineering, ACPEE 2021

作者： Han, Bin Cai, Zhi Chen, Zhongyang Pan, Aiqiang Liu, Jing Dispatching Automation Technology China Electric Power Research Institute Beijing Key Laboratory of Research and System Evaluation of Power Beijing China State Grid Shanghai Electric Power Research Institute Urban Energy Internet Research Center Shanghai China

ISBN: (纸本)9781728191591

At present, China's peak regulation auxiliary service market has been put into operation. According to the actual situation, the peak regulation market rules formulated by various localities have improved the enthusiasm of power generation enterprises in peak regulation to a certain extent. With the development of spot market, the basis of peak regulation market has changed greatly. It is urgent to study the relationship between them. In this paper, the development of peak regulation market is deeply analyzed, and the main problems of peak load regulation are put forward. Then, the adaptability of peak regulation market and spot market is analyzed through scenario comparison, and the necessity of peak regulation market at present stage is explained. Furthermore, the paper studies and puts forward the coordination clearing mode and model between peak regulation market and spot market at the present stage, and verifies its feasibility through a practical example. Finally, some constructive suggestions are put forward for the development of peak regulation market. © 2021 IEEE.

关键词： Power markets

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