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Mercury transformation processes in nature: Critical knowledge gaps and perspectives for moving forward

Journal of Environmental sciences 2022年第9期34卷 152-165页

作者： Zhiyuan Gao Wang Zheng Yanbin Li Yurong Liu Mengjie Wu Shouying Li Ping Li Guangliang Liu Xuewu Fu Shuxiao Wang Feiyue Wang Yong Cai Xinbin Feng Baohua Gu Huan Zhong Yongguang Yin Centre for Earth Observation Science and Department of Environment and GeographyUniversity of ManitobaWinnipegMB R3T 2N2Canada Institute of Surface-Earth System Science Tianjin UniversityTianjin 300192China Key Laboratory of Marine Chemistry Theory and Technology Ministry of Education and College of Chemistry and Chemical EngineeringOcean University of ChinaQingdao 266100China State Key Laboratory of Agricultural Microbiology Huazhong Agricultural UniversityWuhan 430070China School of the Environment Nanjing UniversityState Key Laboratory of Pollution Control and Resource ReuseNanjing 210023China State Key Laboratory of Environmental Geochemistry Institute of GeochemistryChinese Academy of SciencesGuiyang 550081China Department of Chemistry and Biochemistry Florida International UniversityMiamiFL 33199USA School of Environment and State Key Joint Laboratory of Environment Simulation and Pollution Control Tsinghua UniversityBeijing 100084China Environmental Sciences Division Oak Ridge National LaboratoryOak RidgeTennessee 37831USA Environmental and Life Sciences Program(EnLS) Trent UniversityPeterboroughOntario K9L 0G2Canada Research Center for Eco-Environmental Sciences Chinese Academy of SciencesBeijing 100085China

The transformation of mercury(Hg) in the environment plays a vital role in the cycling of Hg and its risk to the ecosystem and human health. Of particular importance are Hg oxidation/reduction and methylation/demethylation processes driven or mediated by the dynamics of light, microorganisms, and organic carbon, among others. Advances in understanding those Hg transformation processes determine our capacity of projecting and mitigating Hg risk. Here, we provide a critical analysis of major knowledge gaps in our understanding of Hg transformation in nature, with perspectives on approaches moving forward. Our analysis focuses on Hg transformation processes in the environment, as well as emerging methodology in exploring these processes. Future avenues for improving the understanding of Hg transformation processes to protect ecosystem and human health are also explored.

关键词： Mercury oxidation reduction methylation demethylation isotope fractionation

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A Binary Sparrow-Hybridized Beluga Whale Optimization Algorithm for Jamming Task Assignment

A Binary Sparrow-Hybridized Beluga Whale Optimization Algori...

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IEEE International Conference on Electronic Information and Communication technology (ICEICT)

作者： Chen Shen Jingpeng Gao Zhiye Jiang Tianran Zhang Geng Chen College of Information and Communication Engineering Harbin Engineering University Harbin China National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing Institute of Space Long March Vehicle Beijing China Beijing Institute of Electronic System Engineering Beijing China

In the context of non-cooperative electronic countermeasures, the problem of formulating effective jamming task assignments arises due to insufficient collaborative jamming resources. This paper proposes a binary sparrow- hybridized beluga whale optimization algorithm based on jamming task assignments. The algorithm combines the binary sparrow search algorithm(BSSA) and the binary beluga whale optimization(BBWO), which is set with multi-dimensional constraints in the time, frequency and spatial domains. To achieve the optimal strategy for collaborative interference task assignment, a fitness function is constructed using both radar coverage and the signal-to-jamming ratio received by each radar. When the number of UAVs is 7 and the number of radars is 10, the simulation results show that the optimization speed and accuracy of the proposed algorithm are significantly higher than the BSSA and BBWO. Therefore, the algorithm has good coverage and performance in the field of jamming task assignments.

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Learning-based high-speed single-pixel imaging using a cyclic random mask

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Optics Express 2025年第12期33卷 25728-25742页

作者： Shuoqi Lin Yichen Zhang Haofan Wang Zunwang Bo Fei Wang Guohai Situ School of Microelectronics Shanghai University Shanghai 200444 China Wangzhijiang Innovation Center for Laser Aerospace Laser Technology and System Department Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences Shanghai 201800 China Key Laboratory of Space Laser Communication and Detection Technology Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences Shanghai 201800 China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of Sciences Beijing 100049 China Shanghai Institute of Laser Technology Shanghai 200233 China ghsitu@***

Single-pixel imaging (SPI) is an advanced computational imaging technique that employs a simple bucket detector to capture object images without raster scanning. This method offers advantages such as low cost, high sensitivity, and suitability for imaging in low-light environments and specialized wavebands. However, SPI inherently suffers from a limitation in imaging speed due to the need to acquire intensity fluctuation signals under a large number of spatially modulated patterns. Here, we tackle this challenge by developing a high-speed optical modulation system and an advanced reconstruction algorithm, which together enhance the refresh rate of the optical modulation process while reducing the required sampling ratios, thereby enabling high-speed SPI. Specifically, on the hardware side, we implement a spinning disk modulation scheme with cyclic random patterns coded onto the disk, achieving a modulation refresh rate of 1 MHz. On the algorithmic side, we propose a physics-enhanced deep learning framework combined with a lightweight neural network, LiteUNet, which reduces the required sampling rate to 10%. By combining these innovations, we experimentally demonstrate high-speed SPI at 1926 fps with a spatial resolution of 71 × 73 pixels. This work offers an effective solution to address the imaging speed bottleneck in SPI, paving the way for its practical applications in fields such as microscopy and remote sensing.

关键词： Computational imaging Imaging techniques Optical systems Single pixel imaging Spatial light modulators Spatial resolution

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Development and prospect of direct‐current circuit breaker in China

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High Voltage 2021年第1期6卷 1-15页

作者： Weijiang Chen Rong Zeng Junjia He Yi Wu Xiaoguang Wei Taixun Fang Zhanqing Yu Zhao Yuan Yifei Wu Wandi Zhou Bing Yang Lu Qu STATE GRID Corporation of China BeijingChina Department of Electrical Engineering Key Laboratory of Control and Simulation of Power System and Generation EquipmentTsinghua UniversityBeijingChina School of Electric and Electronic Engineering Huazhong University of Science&TechnologyWuhanChina School of Electrical Engineering Xi'an Jiaotong UniversityXi'anChina Global Energy Interconnection Research Institute Co. LtdBeijingChina NR Electric Co. LtdNanjingChina

The direct‐current circuit breaker(DCCB)is the most ideal choice for DC fault isolation in DC *** a late start,China's research and development on the DCCB have made outstanding *** article provides a brief glance of current China's DCCB development *** begins by sorting out the technical route according to the topology of *** it systematically summarises both mechanical and hybrid DCCBs with focussing on the aspects of topology structure and principle,key technology and characteristics,prototype development and *** is apparent that Chinese scientists and engineers confronted the worldwide problem of large capacity DC breaking,and put forward a comprehensive solution which consists of an innovative topology structure based on coupled negative voltage circuit,breaking throughs on the key technologies such as highly controllable and reliable fault current commutation,millisecond‐level ultra‐fast and efficient electromagnetic repulsion mechanism,high tolerance and high stability power electronic switch,low residual voltage and fast response energy consumption device,*** article states that the world's first set of hybrid high‐voltage(HV)DCCB,and the first set of mechanical HV DCCB have been *** DCCBs will soon be deployed to the DC grids which have the highest voltage levels therefore require the strongest breaking *** achievements are leading the world in the development and application of *** article also discusses the overall development trends of DCCB in the areas of new topologies,key techno-logical breakthroughs and application scenarios,*** discussions serve as references for DCCB's future technological advancement and its ever‐expanding applications.

关键词： breaking breakthrough discussions

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Frequency Bands and Gaps of Magnetospheric Chorus Waves Generated by Resonant Beam/Plateau Electrons

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Journal of Modern Physics 2022年第6期13卷 864-891页

作者： Konrad Sauer Huayue Chen Eduard Dubinin Quanming Lu CAS Key Laboratory of Geoscience Environment School of Earth and Space Sciences University of Science and Technology of China Hefei China CAS Center of Excellence in Comparative Planetology Hefei China Max-Plnack Institute for Solar System Research G&ouml ttingen Germany

In this paper, the modifications of the whistler dispersion characteristics are investigated which arise if resonant electrons are taken into account. The following chain of processes is emphasized: Generation of whistler waves propagating at different angles to the magnetic field and their nonlinear interaction with resonant electrons result in the appearance of modulated electron beams in the background plasma. As a result, the dispersion characteristics of waves in this new plasma might be significantly changed. By analysing the modified dispersion characteristics these changes are discussed. Supported by particle simulations and space observations, it is assumed that in the electron distribution function at the resonance velocity a plateau-like beam is formed. Because of the weakness of the beam, the term “beam/plateau population (b/p)” is used. By solving the kinetic dispersion relation of whistler waves in electron plasmas with b/p populations, the associated modifications of the whistler dispersion characteristics are presented in diagrams showing, in particular, the frequency versus propagation angle dependence of the excited waves. It is important to point out the two functions of the b/p populations. Because of the bi-directional excitation of whistler waves by temperature anisotropy, one has to distinguish between up- and downstream populations and accordingly between two b/p modes. The interaction of the beam-shifted cyclotron mode ω= Ω_e + k⋅V_b (V_bV_b is the b/p velocity, Ω_e: electron cyclotron frequency) with the whistler mode leads to enhanced damping at the ω-k point where they intersect. This is the origin of the frequency gap at half the electron cyclotron frequency (ω~Ω_e/2) for quasi-parallel waves which are driven by temperature anisotropy. Furthermore, it is shown that the upstream b/p electrons alone (in the absence of temperature anisotropy) can

关键词： Radiation Belts Waves Whistlers Chorus

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Analysis of overload-based cascading failure in multilayer spatial networks

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Chinese Physics B 2020年第9期29卷 404-414页

作者： Min Zhang Xiao-Juan Wang Lei Ji Mei Song Zhong-Hua Liao School of Science Beijing University of Posts and TelecommunicationsBeijing 100876China School of Electronic Engineering Beijing University of Posts and TelecommunicationsBeijing 100876China Beijing Complex Product Advanced Manufacturing Engineering Research Center Beijing Simulation CenterBeijing 100854China State Key Laboratory of Intelligent Manufacturing System Technology Beijing Institute of Electronic System EngineeringBeijing 100854China

Many complex networks in real life are embedded in space and most infrastructure networks are interdependent,such as the power system and the transport *** this paper,we construct two cascading failure models on the multilayer spatial *** our research,the distance l between nodes within the layer obeys the exponential distribution P(l)~exp(-l/ζ),and the length r of dependency link between layers is defined according to node *** entropy approach is applied to analyze the spatial network structure and reflect the difference degree between *** metrics,namely dynamic network size and dynamic network entropy,are proposed to evaluate the spatial network robustness and *** the cascading failure process,the spatial network evolution is analyzed,and the numbers of failure nodes caused by different reasons are also counted,***,we discuss the factors affecting network *** demonstrate that the larger the values of average degree,the stronger the network *** the length r decreases,the network performs *** the probability p is small,asζdecreases,the network robustness becomes more *** p is large,the network robustness manifests better performance asζ*** results provide insight into enhancing the robustness,maintaining the stability,and adjusting the difference degree between nodes of the embedded spatiality systems.

关键词： cascading failure multilayer network load distribution spatial network entropy

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Impacts of Flight Altitude and UAV Posture on the UAV-to-Ground Channel Gain

Impacts of Flight Altitude and UAV Posture on the UAV-to-Gro...

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IEEE Conference on Wireless Communications and Networking

作者： Haoran Ni Boyu Hua Qiuming Zhu Xin Liu Junwei Bao Tongtong Zhou Weizhi Zhong Farman Ali The Key Laboratory of Dynamic Cognitive System of Electromagnetic Spectrum Space Nanjing University of Aeronautics and Astronautics Nanjing China National Mobile Communications Research Laboratory Southeast University Nanjing China School of Information and Communication Engineering Dalian University of Technology Dalian China College of Physics Nanjing University of Aeronautics and Astronautics Nanjing China Qurtuba University of Science and Information Technology

This paper proposes a general unmanned aerial vehicle (UAV)-to-ground (U2G) channel model. The proposed model is consistent with real scenarios by considering the impacts of flight altitude and UAV posture on channel gain. Machine learning and ray tracing (RT) techniques are employed to improve the generation method of altitude-dependent parameters, i.e., path loss (PL) and shadow fading (SF). In addition, posture-related fuselage shadowing coefficient (FSC) is introduced to modify the channel gain, and three-dimensional (3D) geometry modeling of the fuselage is conducted to calculate the FSC. Numerical simulation results show that the flight altitude and UAV posture have obvious effects on channel gain. The proposed model with modified channel gain can effectively describe the PL, SF, and received power under fuselage shadowing. The validity and advantage of the improved channel gain are verified by comparing the simulation results with the measured ones.

关键词： Geometry Three-dimensional displays simulation Machine learning Gain measurement Autonomous aerial vehicles Power capacitors

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Progress toward the sustainable development of world cultural heritage sites facing land-cover changes

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The Innovation 2023年第5期4卷 87-95页

作者： Huadong Guo Fulong Chen Yunwei Tang Yanbin Ding Min Chen Wei Zhou Meng Zhu Sheng Gao Ruixia Yang Wenwu Zheng Chaoyang Fang Hui Lin Ana Pereira Roders Francesca Cigna Deodato Tapete Bing Xu International Research Center of Big Data for Sustainable Development Goals Beijing 100094China Key Laboratory of Digital Earth Science Aerospace Information Research InstituteChinese Academy of SciencesBeijng 100094China International Centre on Space Technologies for Natural and Cultural Heritage Under the Auspices of UNESCO Beijing 100094China Cooperative Innovation Center for Digitalization of Cultural Heritage in Traditional Vllages and Towns Hengyang Normal UniversityHengyang 421010China School of Geography Nanjing Normal UniversityNanjing 210023China Key Laboratory of Poyang Lake Wetland and Watershed Research Ministry of Education&School of Geography and EnvironmentJiangxi Normal UniversityNanchang 330022China Faculty of Architecture and the Built Environment Delft University of Technology2600 AA Delftthe Netherlands Instiute of Atmospheric Sciences and Climate(SAC) National Research Council(CNR)Via del Fosso del Cavaliere 10000133 RomeItaly Italian Space Agency(ASI) Via del Politecnico snc00133 RomeItaly Department of Earth System Science Tsinghua UniversityBeijing 100084China

The quantification of the extent and dynamics of land-use changes is a key metric employed to assess the progress toward several Sustainable Development Goals(SDGs)that form part of the United Nations 2030 Sustainable Development *** terms of anthropogenic factors threatening the conservation of heritage properties,such a metric aids in the assessment of achievements toward heritage sustainability solving the problem of insufficient data ***,in this study,589 cultural World Heritage List(WHL)properties from 115 countries were analyzed,encompassing globally distributed and statistically significant samples of“monuments and groups of buildings”(73.2%),“sites”(19.3%),and“cultural landscapes”(7.5%).Land-cover changes in the WHL properties between 2015 and 2020 were automatically extracted from big data collections of high-resolution satellite imagery accessed via Google Earth Engine using intelligent remote sensing *** indexes(SIs)were estimated for the protection zones of each property,and the results were employed,for the first time,to assess the progress of each country toward SDG Target *** the apparent advances in SIs(10.4%),most countries either exhibited steady(20.0%)or declining(69.6%)SIs due to limited cultural investigations and enhanced negative anthropogenic *** study confirms that land-cover changes are among serious threats for heritage conservation,with heritage in some countries wherein the need to address this threat is most crucial,and the proposed spatiotemporal monitoring approach is recommended.

关键词： landscape heritage Engine

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Revisit of discrete energy bands in Galilean moon’s footprint tails: remote signals of particle absorption

arXiv

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arXiv 2024年

作者： Yang, Fan Zhou, Xu-Zhi Liu, Ying Sun, Yi-Xin Yin, Ze-Fan Hao, Yi-Xin Liu, Zhi-Yang Blanc, Michel Zhao, Jiu-Tong He, Dong-Wen Wu, Ya-Ze Wang, Shan Yue, Chao Zong, Qiu-Gang Institute of Space Physics and Applied Technology Peking University Beijing China State Key Laboratory of Lunar and Planetary Sciences Macau University of Science and Technology Macau999078 China Max Planck Institute for Solar System Research Katlenburg-Lindau Germany Institut de Recherche en Astrophysique et Planétologie CNRS-Universit Paul Sabatier ToulouseCedex France

Recent observations from the Juno spacecraft during its transit over flux tubes of the Galilean moons have identified sharp enhancements of particle fluxes at discrete energies. These banded structures have been suspected to originate from a bounce resonance between particles and standing Alfven waves generated by the moon-magnetospheric interaction. Here, we show that predictions from the above hypothesis are inconsistent with the observations, and propose an alternative interpretation that the banded structures are remote signals of particle absorption at the moons. In this scenario, whether a particle would encounter the moon before reaching Juno depends on the number of bounce cycles it experiences within a fixed section of drift motion determined by moon-spacecraft longitudinal separation. Therefore, the absorption bands are expected to appear at discrete, equally-spaced velocities consistent with the observations. This finding improves our understanding of moon-plasma interactions and provides a potential way to evaluate the Jovian magnetospheric models. © 2024, CC BY.

关键词： Magnetosphere

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Forward-Wave 0 dB Directional Coupler Based on Groove Gap Waveguide technology 4

Forward-Wave 0 dB Directional Coupler Based on Groove Gap Wa...

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4th International Applied Computational Electromagnetics Society Symposium in China, ACES-China 2021

作者： Shen, Ruiliang Feng, Wenjie Shi, Yongrong Nanjing University of Science and Technology Department of Communication Engineering Nanjing China Guangdong Provincial Key Laboratory of Millimeter-Wave and Terahertz South China University of Technology Guangzhou China and and Pazhou Lab Guangzhou China Cognitive System of Electromagnetic Spectrum Space Ministry of Industry and Information Technology Nanjing University of Aeronautics and Astronautics Nanjing China

ISBN: (纸本)9781733509619

In this article, a broadband forward-wave 0 dB coupler is presented using groove gap waveguide (GWG) technology for high frequency band application. The proposed coupler has a broadband flat 0 dB coupling level and lower return losses around 29GHz. The coupler is designed by two adjacent groove GWG coupled through multi symmetric and uniformly-spaced form of apertures on their common wall. The bandwidth according to 0.8-dB allowance is from 27.1 to 31.5 GHz. In the whole operating band, the maximum coupling level is about 0.2dB. The input return losses and isolation level are more than 10dB within the whole operating frequency band. © 2021 Applied Computational Electromagnetics Society (ACES).

关键词： Periodic structures

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