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Worldwide impacts of atmospheric vapor pressure deficit on the interannual variability of terrestrial carbon sinks

National Science Review 2022年第4期9卷 33-40页

作者： Bin He Chen Chen Shangrong Lin Wenping Yuan Hans W.Chen Deliang Chen Yafeng Zhang Lanlan Guo Xiang Zhao Xuebang Liu Shilong Piao Ziqian Zhong Rui Wang Rui Tang State Key Laboratory of Earth Surface Processes and Resource Ecology College of Global Change and Earth System ScienceBeijing Normal University Department of Application Research Twenty First Century Aerospace Technology Co.Ltd. School of Atmospheric Sciences Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai)Sun Yat-sen University Department of Physical Geography and Ecosystem Science Lund University Regional Climate Group Department of Earth SciencesUniversity of Gothenburg Academy of Disaster Reduction and Emergency Management School of GeographyBeijing Normal University State Key Laboratory of Remote Sensing Science Faculty of Geographical ScienceBeijing Normal University Sino-French Institute for Earth System Science College of Urban and Environmental SciencesPeking University

Interannual variability of the terrestrial ecosystem carbon sink is substantially regulated by various environmental variables and highly dominates the interannual variation of atmospheric carbon dioxide（CO2） ***,it is necessary to determine dominating factors affecting the interannual variability of the carbon sink to improve our capability of predicting future terrestrial carbon *** global datasets derived from machine-learning methods and process-based ecosystem models,this study reveals that the inter annual variability of the atmospheric vapor pressure deficit（VPD） was significantly negatively correlated with net ecosystem production（NEP） and substantially impacted the inter annual variability of the atmospheric CO2growth rate（CGR）.Further analyses found widespread constraints of VPD interannual variability on terrestrial gross primary production（GPP）,causing VPD to impact NEP and *** correlation analysis confirms the persistent and widespread impacts of VPD on terrestrial carbon sinks compared to other environmental *** Earth system models underestimate the interannual variability in VPD and its impacts on GPP and *** results highlight the importance of VPD for terrestrial carbon sinks in assessing ecosystems' responses to future climate conditions.

关键词： vapor pressure deficit net ecosystem production gross vegetation production carbon dioxide concentration

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Performance evolution of NI-YSZ anode-supported Sofcs during initial-stage operation 17

Performance evolution of NI-YSZ anode-supported Sofcs during...

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17th International Symposium on Solid Oxide Fuel Cells, SOFC 2021

作者： Lyu, Zewei Han, Minfang Department of Energy and Power Engineering State Key Laboratory of Control and Simulation of Power System and Generation Equipments Tsinghua University Beijing100084 China

ISBN: (纸本)9781607685395

Performance evolution of typical Ni-YSZ anode-supported SOFCs during the initial-stage operation ( 20 h), regardless of the operating current. In the activation stage, the cell performance maintains stable or slightly increases due to the enhanced anode gas-phase diffusion. While in the subsequent aging stage, the cell performance decreases significantly and gradually approaches a plateau in about 100 hours, mainly due to the weakened anode charge transfer reaction and ionic transport processes. Therefore, it is suggested that more efforts should be focused on improving the stability of anode microstructure, especially the stability of anode functional layer. © 2021 Electrochemical Society Inc.. All rights reserved.

关键词： Chemical activation

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ReaxFF molecular dynamic simulation of primary and secondary reactions involving in sub-bituminous coal pyrolysis for tar production

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Carbon Resources Conversion 2021年第1期4卷 230-238页

作者： Yanan Qian Jin-Hui Zhan Wei Xu Zhennan Han Xiaoxing Liu Guangwen Xu State Key Laboratory of Safety and Control for Chemicals SINOPEC Research Institute of Safety Engineering Co.Ltd.Qingdao 266071China State Key Laboratory of Multiphase Complex System Institute of Process EngineeringChinese Academy of SciencesBeijing 100190China Key Laboratory on Resources Chemicals and Materials of Ministry of Education of China Shenyang University of Chemical TechnologyShenyang 110142China

ReaxFF molecular dynamic simulation combined with experimental verification was performed to understand the overall reaction mechanism,especially the primary and secondary reactions involving in tar formation of sub-bituminous coal *** relationship at atomic level is clarified between bond breakage of functional groups and products generation,revealing that the amount and order in forming each product are subject to the number of corresponding functional groups and their bond energies *** primary breakage of-C-O-and-C-C-bridge-bonds present in initial coal macromolecular generates molecular of heavy tar,whereas heavy tar can be converted into light tar through cracking side chain of aromatic rings and cyclic hydrocarbons at increased pyrolysis *** very high temperatures the cracking of short-chain hydrocarbons and residual atoms connecting to aromatic rings further occurs to generate light tar and *** remaining aromatic-ring fragments of heavy tar are likely cross-linked to form ***,the simultaneous evolution tendency of tar yield and tar quality under different pyrolysis temperatures and heating rates is obtained at molecular *** obtaining high yield and quality of tar,appropriately high temperature as well as suitable heating rate are needed to compromise the high yield of primary tar and high quality of secondarily upgraded products.

关键词： ReaxFF MD simulation Sub-bituminous coal pyrolysis Reaction paths Primary formation Secondary upgrading

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Optimization of methane reforming for high efficiency and stable operation of SOFC stacks 17

Optimization of methane reforming for high efficiency and st...

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17th International Symposium on Solid Oxide Fuel Cells, SOFC 2021

作者： Liu, Yaodong Lyu, Zewei Han, Minfang Department of Energy and Power Engineering State Key Laboratory of Control and Simulation of Power System and Generation Equipments Tsinghua University Beijing100084 China

ISBN: (纸本)9781607685395

Solid Oxide Fuel Cells (SOFCs) provides an efficient and clean pathway to generate electricity. In addition to hydrogen, SOFCs also hold the possibility for the utilization of a variety of carbon containing fuels. A practical kilowatt-class SOFC system fueled by methane has been preliminarily integrated previously. This study intended to obtain the optimized working conditions for the prereformer, with which the SOFC module can exhibit higher electrical performance. Detailed thermodynamic analysis and experimental measurements of steam methane reforming (SMR) were carried out under different steam to carbon ratios (S/C) and temperatures, where the experimental results matched well with the thermodynamic calculation. Based on the optimized working condition of SMR, the electrical performance and stability of a planar single-layer stack (10×10 cm2) fueled by the reformate syngas was evaluated. The maximum electrical efficiency reached 65.39% (LHV) at 750 C, and 50-hour stable operation under 50% (LHV) electrical efficiency was achieved. © 2021 Electrochemical Society Inc.. All rights reserved.

关键词： Electrical efficiency

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Distributed control strategy for transactive energy prosumers in real-time markets

Energy Conversion and Economics

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Energy Conversion and Economics 2022年第1期3卷 1-10页

作者： Yin, Chen Ding, Ran Xu, Haixiang Li, Gengyin Chen, Xiupeng Zhou, Ming State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources School of Electrical and Electronic Engineering North China Electric Power University Beijing China State Grid Jibei Electric Power Co. Ltd. Beijing China Engineering and Technology Institute Groningen University of Groningen Groningen Netherlands

The increasing penetration of distributed energy resources (DERs) has led to increasing research interest in the cooperative control of multi-prosumers in a transactive energy (TE) paradigm. While the existing literature shows that TE offers significant grid flexibility and economic benefits, few studies have addressed the incorporation of security constraints in TE. Herein, a market-based control mechanism in real-time markets is proposed to economically coordinate the TE among prosumers while ensuring secure system operation. Considering the dynamic characteristics of batteries and responsive demands, a model predictive control (MPC) method is used to handle the constraints between different time intervals and incorporate the following generation and consumption predictions. Owing to the computational burden and individual privacy issues, an efficient distributed algorithm is developed to solve the optimal power flow problem. The strong coupling between prosumers through power networks is removed by introducing auxiliary variables to acquire locational marginal prices (LMPs) covering energy, congestion, and loss components. Case studies based on the IEEE 33-bus system demonstrated the efficiency and effectiveness of the proposed method and model. © 2022 The Authors. Energy Conversion and Economics published by John Wiley & Sons Ltd on behalf of The Institution of engineering and Technology and the state Grid Economic & Technological Research institute Co., Ltd.

关键词： Model predictive control

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Machine learning in laser-induced breakdown spectroscopy:A review

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Frontiers of physics 2024年第6期19卷 225-252页

作者： Zhongqi Hao Ke Liu Qianlin Lian Weiran Song Zongyu Hou Rui Zhang Qianqian Wang Chen Sun Xiangyou Li Zhe Wang Key Laboratory of Nondestructive Testing(Ministry of Education) Nanchang Hangkong UniversityNanchang 330063China Wuhan National Laboratory for Optoelectronics(WNLO) Huazhong University of Science and TechnologyWuhan 430074China State Key Lab of Power System Department of Energy and Power EngineeringTsinghua-BP Clean Energy CentreTsinghua UniversityBeijing100084China School of Optics and Photonics Beijing Institute of TechnologyBeijing 100081China School of Physics and Astronomy Shanghai Jiao Tong UniversityShanghai 200240China School of Public Health Xinjiang Medical UniversityUrumqi 830054China The Second Medical College of Binzhou Medical University Yantai Affiliated Hospital of Binzhou Medical UniversityYantai264100China School of Electronic Engineering Naval University of EngineeringWuhan 430014China

Laser-induced breakdown spectroscopy(LIBS)is a spectroscopic analytic technique with great application potential because of its unique advantages for online/in-situ ***,due to the spatially inhomogeneity and drastically temporal varying nature of its emission source,the laser-induced plasma,it is difficult to find or hard to generate an appropriate spatiotemporal window for high repeatable signal collection with lower matrix *** quantification results of traditional physical principle based calibration model are unsatisfactory since these models were not able to compensate for complicate matrix effects as well as signal *** learning is an emerging approach,which can intelligently correlated the complex LIBS spectral data with its qualitative or/and quantitative composition by establishing multivariate regression models with greater potential to reduce the impacts of signal fluctuation and matrix effects,therefore achieving rela-tively better qualitative and quantitative *** this review,the progress of machine learning application in LIBS is summarized from two main aspects:(i)Pre-processing data for machine learning model,including spectral selection,variable reconstruction,and denoising to improve qualitative/quantitative performance;(ii)Machine learning methods for better quantification performance with reduction of the impact of matrix effect as well as LIBS spectra *** review also points out the issues that researchers need to address in their future research on improving the performance of LIBS analysis using machine learning algorithms,such as restrictions on training data,the disconnect between physical principles and algorithms,the low generalization ability and massive data processing ability of the model.

关键词： laser-induced breakdown spectroscopy machine learning repeatability matrix effects qualitative and quantitativeanalysis

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Oxidation Mechanism and Toxicity Evolution of Linalool,a Typical Indoor Volatile Chemical Product

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Environment & Health 2024年第7期2卷 486-498页

作者： Zihao Fu Song Guo Ying Yu Hong-Bin Xie Shiyu Li Daqi Lv Putian Zhou Kai Song Zheng Chen Rui Tan Kun Hu Ruizhe Shen Maosheng Yao Min Hu State Key Joint Laboratory of Environmental Simulation and Pollution Control International Joint Laboratory for Regional Pollution ControlMinistry of Education(IJRC)College of Environmental Sciences and EngineeringPeking UniversityBeijing 100871China Collaborative Innovation Center of Atmospheric Environment and Equipment Technology Nanjing University of Information Science&TechnologyNanjing 210044China Key Laboratory of Industrial Ecology and Environmental Engineering(Ministry of Education) School of Environmental Science and TechnologyDalian University of TechnologyDalian 116024China Institute for Atmospheric and Earth System Research/Physics Faculty of ScienceUniversity of HelsinkiP.O.Box 64FIN-00014 HelsinkiFinland

Linalool,a high-reactivity volatile chemical product(VCP)commonly found in cleaning products and disinfectants,is increasingly recognized as an emerging contaminant,especially in indoor *** the gas-phase oxidation mechanism of linalool is crucial for assessing its impact on atmospheric chemistry and human *** quantum chemical calculations and computational toxicology simulations,we investigated the atmospheric transformation and toxicity evolution of linalool under low and high NO/HO_(2)·levels,representing indoor and outdoor *** findings reveal that linalool can undergo the novel mechanisms involving concerted peroxy(RO_(2)·)and alkoxy radical(RO·)modulated autoxidation,particularly emphasizing the importance of cyclization reactions *** expands the widely known RO_(2)·-dominated H-shift-driven autoxidation and proposes a generalized autoxidation mechanism that leads to the formation of low-volatility secondary organic aerosol(SOA)*** analysis shows that over half of transformation products(TPs)exhibited higher carcinogenicity and respiratory toxicity compared to *** also propose time-dependent toxic effects of TPs to assess their long-term *** results indicate that the strong indoor emission coupled with slow consumption rates lead to significant health risks under an indoor *** results highlight complex indoor air chemistry and health concerns regarding persistent toxic products during indoor cleaning,which involves the use of linalool or other VCPs.

关键词： volatile chemical products(VCPs) peroxy radicals(RO_(2)·) atmospheric autoxidation secondary organic aerosol(SOA) computational toxicology

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Fabrication of a high-power pump and signal combiner with an asymmetric tapered fiber bundle utilizing un-pretreated pump fibers

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Optics Express 2025年第6期33卷 12349-12360页

作者： Ji, Mengyuan Liu, Kai Chen, Wenqi Yi, Xuezhuan Wang, Meng Tian, Lei Meng, Junqing Wangzhijiang Innovation Center for Laser Aerospace Laser Technology and System Department Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences Shanghai201800 China Shanghai Key Laboratory of All Solid-State Laser and Applied Techniques Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences Shanghai201800 China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of Sciences Beijing100049 China Advanced Laser and Optoelectronic Functional Materials Department Special Glasses and Fibers Research Center Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences Shanghai201800 China Beijing Institute of Tracking and Telecommunication Technology Beijing100049 China

We report a fabrication method for addressing the non-uniform arrangement issues associated with the asymmetric tapered fiber bundles (TFBs) in high-power pump and signal combiners (PSCs), which do not require pre-treatment of the pump fibers. It employs a homemade thin-walled glass tube with the coating layer, and six pump fibers surround it evenly to collectively form the TFB, while the signal fiber remains unaffected during the tapering process of the fiber bundle. The 3D simulation model of the backward (6 + 1)×1 PSC was established by the refractive index distribution method to calculate the transmission efficiency of the pump light and signal light, and then identify the optimal preparation parameters for achieving the best efficiency. In this model, a simulated quasi-uniform energy distribution light field was used as the input of the pump fiber, which can optimize the previous calculation method. Experimental results exhibited that the backward (6 + 1)×1 PSC achieved signal light and pump light transmission efficiencies of over 96% and 98%, respectively, the beam quality degradation is ∆M2 = 0.09, and the total output pump power was 4.102 kW. The experimental results are in good agreement with the simulation results. © 2025 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.

关键词： Refractive index

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Performance Analyses of a High-Frequency Transformers With Different Magnetic Cores

Performance Analyses of a High-Frequency Transformers With D...

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2024 IEEE Transportation Electrification Conference and Expo, Asia-Pacific, ITEC Asia-Pacific 2024

作者： Li, Yanlei Ma, Yingtao Zhang, Jiepin Wu, Feiao Li, Dong China Academy Of Railway Sciences Corporation Limited State Key Laboratory For Traction And Control System Of Emu And Locomotive Beijing100861 China China Academy Of Railway Sciences Corp. Ltd. Locomotive&Car Research Institute Beijing100861 China Beijing Zongheng Electromechanical Technology Co. Ltd. Beijing100861 China Beijing Jiaotong University School Of Electrical Engineering Beijing10044 China

ISBN: (纸本)9798331529277

Taking advantages of the high power density and high efficiency, High Frequency Transformers (HFT) have been widely applied in the electrified transportation. However, the low saturation flux density and large core loss has limited the increase of the power. In the paper, the core loss calculation method of HFT operated under high frequency non-sinusoidal excitation are presented. Then the flux density and efficiency of HFT with double E-type and C-type core structures are compared. The finite element method was taken to analyze the performances of HFT with different core materials and different operation current waveforms. The relations of the efficiency with the power, core clearance, and operation frequency are also studied. Then the experimental results are carried out on the prototype of 60 kW HFT to verify the accuracy of the calculation results. © 2024 IEEE.

关键词： Distribution transformers

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Quantitative detection of alkali metal Na based on laser-induced breakdown spectroscopy technology

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Meitan Xuebao/Journal of the China Coal Society 2025年第4期50卷 2262-2270页

作者： Shen, Sijie Li, Chi Zhou, Wangzheng Wang, Zhenzhen Yan, Junjie Hou, Zongyu Wang, Zhe Deguchi, Yoshihiro School of Energy and Power Engineering Xi'an Jiaotong University Xi'an710049 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China State Key Laboratory of Power System Operation and Control Tsinghua University Beijing100084 China Institute for Carbon Neutrality Tsinghua University Beijing100084 China Department of Energy and Power Engineering Tsinghua University Beijing100084 China Shanxi Research Institute for Clean Energy Tsinghua University Taiyuan030032 China Graduate School of Technology Industrial and Social Sciences Tokushima University Tokushima770-8506 Japan

The alkali metal compounds released from high alkali fuels such as low-quality coal during thermal utilization can affect the normal operation of thermal equipment. Therefore, rapid online detection of alkali metal content in low-quality coal is of great significance for controlling alkali metal release during combustion. The alkali metal Na element is used as the detection object, and the mixed samples of graphite and sodium chloride powder with different ratios are used as experimental samples. The influencing factors of measuring Na element in samples using laser induced breakdown spectroscopy (LIBS) technology are studied. The impact of two signal strength calculation methods on signal stability is compared. The influence of experimental parameters on signal strength and signal-to-noise ratio is analyzed. The quantitative calculation models for Na element have been established. Research has shown that the characteristic spectral lines of Na element, Na I 588.995 nm and Na I 589.592 nm, are suitable as the main analytical spectral lines. Using the area intensity of the dual line characteristic spectral lines of Na element as the signal intensity can effectively improve signal stability. When the laser energy is 60 mJ and the delay time is 1 000 ns, the relative standard deviation of spectral signal intensity is low and the signal-to-noise ratio is high. The quantitative calculation models are established using traditional calibration method, partial least squares (PLS) method, and support vector machine (SVR) with spectral signal intensity as the input and Na element addition in the sample as the output. The accuracy of each model is compared and analyzed. The results indicate that the PLS model may exhibit overfitting when the sample size is small and the input quantity is large. The fitting accuracy of the SVR model is 0.978 3, the root mean square percentage error of the training set is 13.42%, and the root mean square percentage error of the test set is 13.51

关键词： Sodium chloride

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