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Observation-based sources evolution of non-methane hydrocarbons (NMHCs) in a megacity of China

Journal of Environmental Sciences 2023年第2期124卷 794-805页

作者： Yarong Peng Hongli Wang Qian Wang Shengao Jing Jingyu An Yaqin Gao Cheng Huang Rusha Yan Haixia Dai Tiantao Cheng Qiang Zhang Meng Li Jianlin Hu Zhihao Shi Li Li Shengrong Lou Shikang Tao Qinyao Hu Jun Lu Changhong Chen Department of Environmental Science and Engineering Shanghai Key Laboratory of Atmospheric Particle Pollution and PreventionInstitute of Atmospheric SciencesFudan UniversityShanghai 200438China State Environmental Protection Key Laboratory of Formation and Prevention of Urban Air Pollution Complex Shanghai Academy of Environmental SciencesShanghai 200233China Department of Atmospheric and Oceanic Sciences Institute of Atmospheric SciencesFudan UniversityShanghai 200438China Department of Earth System Science Ministry of Education Key Laboratory for Earth System ModelingTsinghua UniversityBeijing 100084China Big Data Institute for Carbon Emission and Environmental Pollution Fudan UniversityShanghai 200438China School of Environmental Science and Engineering Nanjing University of Information Science&TechnologyNanjing 210044China

Both concentrations and emissions of many air pollutants have been decreasing due to implement of control measures in China,in contrast to the fact that an increase in emissions of non-methane hydrocarbons(NMHCs)has been *** study employed seven years continuous NMHCsmeasurements and the related activities data of Shanghai,a megacity in China,to explore evolution of emissions and effectiveness of air pollution control *** mixing ratio of NMHCs showed no statistical interannual changes,of which their compositions exhibited marked *** resulted in a decreasing trend of ozone formation potential by 3.8%/year(p<0.05,the same below),which should be beneficial to ozone pollution mitigation as its production in Shanghai is in the NMHCs-limited *** alkanes,aromatics and acetylene changed by+3.7%/year,-5.9%/year and-7.4%/year,respectively,and alkenes showed no apparent *** sources were apportioned by a positive matrix factorization ***,vehicular emissions(-5.9%/year)and petrochemical industry emissions(-7.1%/year)decreased significantly,but the decrease slowed down;significant reduction in solvent usage(-9.0%/year)appeared after 2010;however,emissions of natural gas(+12.6%/year)and fuel evaporation(with an increasing fraction)became more *** inconsistency between observations and inventories was found in interannual trend and speciation as well as source contributions,emphasizing the need for further validation in NMHCs emission *** study confirms the effectiveness of measures targeting mobile and centralized emissions from industrial sources and reveals a need focusing on fugitive emissions,which provided new insights into future air policies in polluted region.

关键词： Characteristics Source apportionment Observation-based Interannual trend Shanghai

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Integrated optical frequency transfer and optical physical layer key distribution with enhanced link reciprocity detection

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Science China(Information Sciences) 2024年第7期67卷 335-336页

作者： Kunfeng XIE Liang HU Jianping CHEN Guiling WU State Key Laboratory of Advanced Optical Communication System and Networks Department of Electronic EngineeringShanghai Jiao Tong University

Optical fiber transmission has been widely used in communications and metrology, wherein optical frequency transfer (OFT) and optical physical layer secure key distribution (OKD) have become research hotspots [1, 2]. Moreover,OFT can perform a comparison between state-of-the-art optical atomic clocks and implement coherent optical phase transfer over long distances to support geodesy [1, 3].

关键词： distribution integrated physical detection layer link with enhanced frequency optical

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Design, Modeling and Control of a Dielectric Elastomer Actuated Micro-positioning Stage 16th

Design, Modeling and Control of a Dielectric Elastomer Ac...

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16th International Conference on Intelligent robotics and Applications, ICIRA 2023

作者： Yan, Peinan Gu, Guoying Zou, Jiang Robotics Institute School of Mechanical Engineering Shanghai Jiao Tong University Shanghai200240 China State Key Laboratory of Mechanical System and Vibration School of Mechanical Engineering Shanghai Jiao Tong University Shanghai200240 China

ISBN: (纸本)9789819964918

In this paper, we propose one kind of a dielectric elastomer actuated micro-positioning stage (DEAMS) that can achieve both large stroke and high resolution. To this end, a customized multilayer dielectric elastomer actuator (DEA), made of silicone, is designed and fabricated, which can generate a linear movement. Then based on the DEA, a DEAMS is designed with a stroke of nearly 1 mm and resolution of 480 nm. Next, several dynamic tests are conducted to reveal its dynamic responses: i) the natural frequency of the DEAMS can reach 80 Hz;ii) its output displacement shows both slow-time creep and rate-dependent hysteresis because of the inherent viscoelasticity. Lastly, a direct inverse hysteresis compensation (DIHC) controller based on a phenomenological hysteresis model and a closed-loop controller are adopted to remove hysteresis and creep, respectively. Experimental results demonstrate that with our control method, the DEAMS can achieve high-precision tracking control, which may pave the way for its applications in the field of micro/nano manipulations. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd 2023.

关键词： Silicones

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Continual learning fault diagnosis:A dual-branch adaptive aggregation residual network for fault diagnosis with machine increments

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Chinese Journal of Aeronautics 2023年第6期36卷 361-377页

作者： Bojian CHEN Changqing SHEN Juanjuan SHI Lin KONG Luyang TAN Dong WANG Zhongkui ZHU School of Rail Transportation Soochow UniversitySuzhou 215131China China Chang Guang Satellite Technology CO.LTD Changchun 130102China Department of Industrial Engineering and Management and in the State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong UniversityShanghai 200030China

As a data-driven approach, Deep Learning(DL)-based fault diagnosis methods need to collect the relatively comprehensive data on machine fault types to achieve satisfactory performance. A mechanical system may include multiple submachines in the real-world. During condition monitoring of a mechanical system, fault data are distributed in a continuous flow of constantly generated information and new faults will inevitably occur in unconsidered submachines, which are also called machine increments. Therefore, adequately collecting fault data in advance is difficult. Limited by the characteristics of DL, training existing models directly with new fault data of new submachines leads to catastrophic forgetting of old tasks, while the cost of collecting all known data to retrain the models is excessively high. DL-based fault diagnosis methods cannot learn continually and adaptively in dynamic environments. A new Continual Learning Fault Diagnosis method(CLFD) is proposed in this paper to solve a series of fault diagnosis tasks with machine increments. The stability–plasticity dilemma is an intrinsic issue in continual learning. The core of CLFD is the proposed Dual-branch Adaptive Aggregation Residual Network(DAARN).Two types of residual blocks are created in each block layer of DAARN: steady and dynamic blocks. The stability–plasticity dilemma is solved by assigning them with adaptive aggregation weights to balance stability and plasticity, and a bi-level optimization program is used to optimize adaptive aggregation weights and model parameters. In addition, a feature-level knowledge distillation loss function is proposed to further overcome catastrophic forgetting. CLFD is then applied to the fault diagnosis case with machine increments. Results demonstrate that CLFD outperforms other continual learning methods and has satisfactory robustness.

关键词： Catastrophic forgetting Continual learning Fault diagnosis Knowledge distillation Machine increments Stability-plasticity dilemma

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Determination of defect size for composites using derivative images in pulse thermography

Determination of defect size for composites using derivative...

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2024 International Conference on Optical and Photonic Engineering, icOPEN 2024

作者： Wei, Yanjie Lu, Jiashuo Xiao, Yao Gu, Xiaohui State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang050043 China Department of Engineering Mechanics Shijiazhuang Tiedao University Shijiazhuang050043 China

ISBN: (数字)9781510688117

ISBN: (纸本)9781510688100

Pulse thermography is a reliable method for detecting defects in composites with advantages of full field, non-contact and easy operation. However, the size determination of subsurface defects with low width-to-depth ratios using pulsed thermography is a challenging task due to the blurred defect edges in infrared thermal images caused by lateral heat diffusion. The present study explores the ability of time derivative images of infrared thermography to predict defect size. 2D thermal conduction of pulse thermography based on the virtual heat source method was analyzed to compare the temperature profile and derivative profile of defects along the diameter direction, and a size prediction method based on the derivative profile is proposed. The feasibility of the proposed method was evaluated by measuring the dimensions of the flat-bottomed holes in the composite panels. The experimental results demonstrated that the size inversion method based on derivative images brings an improvement in measuring accuracy for defects. Additionally, the influences of cooling time, defect depth, defect size and thermal properties of the material on the measurement of defect dimension are also discussed. © 2025 SPIE.

关键词： Thermography (imaging)

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Review on Modeling of Impact of Extreme Weather on Source-Grid-Load-Storage 7

Review on Modeling of Impact of Extreme Weather on Source-Gr...

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7th IEEE Conference on Energy Internet and Energy system Integration, EI2 2023

作者： Lv, Yan Sun, Bo Wang, Miao Jiao, Yonggang Song, Xuri Luo, Yadi Lu, Peng China Electric Power-Research Institute National Key Laboratory of Power Grid-Safety Beijing China Tsinghua University State Key Laboratory of Power System Department of Electrical Engineering Beijing Haidian District China

ISBN: (纸本)9798350345094

Source-Grid-Load-Storage (SGLS) is an important part of a power system, and each part affects the safe operation of the power system. In extreme weather conditions, the SGLS link in the power system will be affected. This article starts from the four aspects of 'source-grid-load-storage', first analyzing the impact of normal weather and extreme weather on power system operation, then modeling the 'source-grid-load-storage' based on several typical extreme weather scenarios, and then presenting several technical solutions to cope with extreme weather. Finally, the related issues of 'source-grid-load-storage' and the future development direction are summarized. © 2023 IEEE.

关键词： Meteorology

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Radar Based Gesture Recognition in Embedded systems 6

Radar Based Gesture Recognition in Embedded Systems

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6th International Conference on Electronics Technology, ICET 2023

作者： Liang, Tingxuan Lin, Yue Xu, Hongtao Fudan University State Key Laboratory of Integrated Chips & System Department of Microelectronics Shanghai China R&d ICLegend Micro Nanjing China

ISBN: (纸本)9798350337693

Gesture recognition has played a significant role in human-computer interaction. Millimeter-wave radar sensor is a class of necessary sensor for human gesture recognition in an indoor condition due to its advantages of private protection, low hardware cost. However, for gesture recognition application, it is difficult for us to meet the requirements of high accuracy and real-time simultaneously in embedded system. Unlike other conventional method which increase the cost of hardware of embedded system to improve detection accuracy, in this paper, we proposed a radar-based gesture recognition in low power consumption and low-cost embedded system by using 24 GHz millimeter-wave radar with 1 transmitting antenna and 2 receiving antenna channels. Besides, 2D trajectory information on XY coordination and lightweight deep neural network have been used to distinct ten air-writing numbers. As a result, this system could reconstruct the air-writing symbols and recognize numeric character 0-9 with 95.2% accuracy in real time. © 2023 IEEE.

关键词： Embedded systems

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1λ 1.6-Tb/s Direct Detection via a Hybrid Optical Hilbert Receiver and Stokes Vector Receiver

1λ 1.6-Tb/s Direct Detection via a Hybrid Optical Hilbert R...

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2024 IEEE Photonics Conference, IPC 2024

作者： Zhu, Yixiao Fang, Xiansong Zhou, Lingjun Zhu, Junbo Li, Yunchen Zhou, Xian Zhong, Kangping Tao Lau, Alan Pak He, Zhixue Wang, Lei Hu, Weisheng Li, Ke Zhang, Fan Peking University State Key Laboratory of Advanced Optical Communication System and Networks Beijing100871 China University of Science and Technology Beijing Beijing100083 China The Hong Kong Polytechnic University Photonics Research Institute Department of Electrical and Electronic Engineering Hong Kong Shanghai Jiao Tong University State Key Laboratory of Advanced Optical Communication System and Networks Shanghai200240 China Pengcheng Laboratory Shenzhen518000 China

ISBN: (纸本)9798350361957

We propose a hybrid optical Hilbert receiver and Stokes vector receiver (OH-SVR) capable of phase and polarization diversity. We experimentally demonstrate single-wavelength direct detection at 1.6-Tb/s and 1.56-Tb/s line rates at BTB and after 10-km standard single-mode fiber transmission for data-center interconnects. © 2024 IEEE.

关键词： Single mode fibers

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Improving Collision-Free Success Rate For Object Goal Visual Navigation Via Two-Stage Training With Collision Prediction

arXiv

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arXiv 2025年

作者： Lian, Shiwei Zhang, Feitian Robotics and Control Laboratory Department of Advanced Manufacturing and Robotics College of Engineering State Key Laboratory of Turbulence and Complex Systems Peking University Beijing100871 China

The object goal visual navigation is the task of navigating to a specific target object using egocentric visual observations. Recent end-to-end navigation models based on deep reinforcement learning have achieved remarkable performance in finding and reaching target objects. However, the collision problem of these models during navigation remains unresolved, since the collision is typically neglected when evaluating the success. Although incorporating a negative reward for collision during training appears straightforward, it results in a more conservative policy, thereby limiting the agent’s ability to reach targets. In addition, many of these models utilize only RGB observations, further increasing the difficulty of collision avoidance without depth information. To address these limitations, a new concept—collision-free success is introduced to evaluate the ability of navigation models to find a collision-free path towards the target object. A two-stage training method with collision prediction is proposed to improve the collision-free success rate of the existing navigation models using RGB observations. In the first training stage, the collision prediction module supervises the agent’s collision states during exploration to learn to predict the possible collision. In the second stage, leveraging the trained collision prediction, the agent learns to navigate to the target without collision. The experimental results in the AI2-THOR environment demonstrate that the proposed method greatly improves the collision-free success rate of different navigation models and outperforms other comparable collision-avoidance methods. Copyright © 2025, The Authors. All rights reserved.

关键词： Deep reinforcement learning

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Trends and drivers of anthropogenic NOx emissions in China since 2020

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Environmental Science and Ecotechnology 2024年第5期21卷 287-293页

作者： Hui Li Bo Zheng Yu Lei Didier Hauglustaine Cuihong Chen Xin Lin Yi Zhang Qiang Zhang Kebin He Shenzhen Key Laboratory of Ecological Remediation and Carbon Sequestration Institute of Environment and EcologyTsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen 518055China State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex Beijing 100084China State Environmental Protection Key Laboratory of Environmental Planning and Policy Simulation and Center of Air Quality Simulation and System Analysis Chinese Academy of Environmental PlanningBeijing 100041China Laboratoire des Sciences du Climat et de l’Environnement LSCE/IPSLCEA-CNRS-UVSQUniversite Paris-SaclayGif-sur-YvetteFrance Center for Satellite Application on Ecology and Environment Ministry of Ecology and Environment of ChinaBeijing 100094China Institute of Future Human Habitats Tsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen 518055China Ministry of Education Key Laboratory for Earth System Modeling Department of Earth System ScienceTsinghua UniversityBeijing 100084China State Key Joint Laboratory of Environment Simulation and Pollution Control School of EnvironmentTsinghua UniversityBeijing 100084China

Nitrogen oxides(NOx),significant contributors to air pollution and climate change,form aerosols and ozone in the ***,timely,and transparent information on NOx emissions is essential for decision-making to mitigate both haze and ozone ***,a comprehensive understanding of the trends and drivers behind anthropogenic NOx emissions from Chinadthe world's largest emitterdhas been lacking since 2020 due to delays in emissions *** we show a consistent decline in China's NOx emissions from 2020 to 2022,despite increased fossil fuel consumption,utilizing satellite observations as constraints for NOx emission estimates through atmospheric *** reduction is corroborated by data from two independent spaceborne instruments:the TROPOspheric Monitoring Instrument(TROPOMI)and the Ozone Monitoring Instrument(OMI).Notably,a reduction in transport emissions,largely due to the COVID-19 lockdowns,slightly decreased China's NOx emissions in *** subsequent years,2021 and 2022,reductions in NOx emissions were driven by the industry and transport sectors,influenced by stringent air pollution *** satellite-based inversion system developed in this study represents a significant advancement in the real-time monitoring of regional air pollution emissions from space.

关键词： China's NOx emissions Pollution control Socio-economic drivers Atmospheric inversion

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