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4th IEEE International Conference on Electronic Information and Communication technology, ICEICT 2021

作者： Jin, Xiaolin Ma, Jing Ye, Fang College of Infomation and Communication Engineering Harbin Engineering University Harbin150001 China Key Laboratory of Advanced Marine Communication and Information Technology Ministry of Industry and Information Technology Beijing100854 China Science and Technology on Special System Simulation Laboratory Beijing100854 China

ISBN: (纸本)9781665432030

To address the problem of poor recognition success rate (RSR) of low probability of intercept (LPI) radar signals such as polyphase codes at low signal-to-noise ratio (SNR), In this paper, we propose a method of deep neural network with attention mechanism for modulation recognition of radar signals. The method first transforms the received radar signal into a two-dimensional time-frequency image(TFI), and then we obtain a binary time-frequency image by threshold segmentation，and resize TFIs through bicubic interpolation. While a deep residual network with Convolutional Block Attention Module (CBAM) is designed to recognize the radar signals. We take advantage of the attention mechanism to find the effective feature information in the noise and increase the effective information weight to further improve the recognition success rate of radar signals under low SNR. Finally, the average RSR of the method is nearly 96% for 7 signals at -6dB. © 2021 IEEE

关键词： Deep neural networks

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The impact of the atmospheric turbulence-development tendency on new particle formation: a common finding on three continents

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National science Review 2021年第3期8卷 140-150页

作者： Hao Wu Zhanqing Li Hanqing Li Kun Luo Yuying Wang Peng Yan Fei Hu Fang Zhang Yele Sun Dongjie Shang Chunsheng Liang Dongmei Zhang Jing Wei Tong Wu Xiaoai Jin Xinxin Fan Maureen Cribb Marc L.Fischer Markku Kulmala Tuukka Pet?j? State Key Laboratory of Remote Sensing Science College of Global Change and Earth System ScienceBeijing Normal University ESSIC and Department of Atmospheric Science University of MarylandCollege Park State Key Laboratory of Clean Energy Utilization Zhejiang University School of Atmospheric Physics Nanjing University of Information Science and Technology Meteorological Observation Center China Meteorological Administration State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry Institute of Atmospheric Physics Chinese Academy of Sciences State Key Joint Laboratory of Environmental Simulation and Pollution Control College of Environmental Sciences and Engineering Peking University State Key Joint Laboratory of Environment Simulation and Pollution Control School of Environment Tsinghua University Lawrence Berkeley National Laboratory Institute for Atmospheric and Earth System Research/Physics Faculty of ScienceUniversity of Helsinki Aerosol and Haze Laboratory Beijing Advanced Innovation Center for Soft Matter Science and Engineering Beijing University of Chemical Technology Joint International Research Laboratory of Atmospheric and Earth System Sciences School of Atmospheric Sciences Nanjing University

A new mechanism of new particle formation(NPF) is investigated using comprehensive measurements of aerosol physicochemical quantities and meteorological variables made in three continents,including beijing,China;the Southern Great Plains site in the USA;and SMEAR Ⅱ Station in Hyytiala,Finland.D espite the considerably different emissions of chemical species among the sites,a common relationship was found between the characteristics of NPF and the stability *** stability parameter(ζ=Z/L,where Z is the height above ground and L is the Monin-Obukhov length) is found to play an important role;it drops significantly before NPF as the atmosphere becomes more unstable,which may serve as an indicator of nucleation *** the atmosphere becomes unstable,the NPF duration is closely related to the tendency for turbulence development,which influences the evolution of the condensation ***,the unstable atmosphere may dilute pre-existing particles,effectively reducing the condensation sink,especially at coarse mode to foster *** new mechanism is confirmed by model simulations using a molecular dynamic model that mimics the impact of turbulence development on nucleation by inducing and intensifying homogeneous nucleation events.

关键词： new particle formation turbulence development molecular dynamic

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The enhanced role of formic acid on sulfuric acid-ammonia-driven nucleation in forest regions and polluted city areas

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Journal of Environmental sciences 2025年

作者： Shasha Chen Rongrong Li Chengyan Zhang Shuqin Wei Rui Wang Biwu Chu Xiaomeng Zhang Hao Li Tianlei Zhang Institute of Theoretical and Computational Chemistry Shaanxi Key Laboratory of Catalysis School of Chemical and Environment Science Shaanxi University of Technology Hanzhong 723001 China State Key Joint Laboratory of Environment Simulation and Pollution Control Research Center for Eco-environmental Sciences Chinese Academy of Sciences Beijing 100085 China

Formic acid (FA) is particularly prominent for its ubiquity and structural simplicity among atmospheric organic acids, and exerts a significant influence on atmospheric acidity. However, the potential contribution of FA to the primary stage of new particle formation (NPF) remains unclear. Herein, molecular dynamics (MD), density functional theory (DFT) and the atmospheric cluster dynamics code (ACDC) model have been utilized to evaluate the mechanism of FA participation in atmospheric SA (sulfuric acid)-A (ammonia) clusters. The MD simulations qualitatively suggest that FA can aggregate with SA and A to form larger clusters, and the aggregation time of the largest clusters decreases as the temperature decreases. The DFT and ACDC findings indicate that the ternary SA-A-FA system is thermodynamically more stable at low temperatures (238.15 K). Simultaneously, in regions with low temperatures, high [FA] (10 11 molecules/cm 3 ), low [SA] (10 6 molecules/cm 3 ) and high [A] (10 11 molecules/cm 3 ), FA significantly enhances SA-A cluster formation rates. The low-temperature NPF mechanism implies that FA could facilitate the growth of pure SA-A clusters via a “catalytic” mechanism and play an integral role in the genesis of critical clusters as a “participant”. This dual role differs from the “catalytic” role exhibited by malonic and glycolic acids in our previous studies. This discovery could help identify the sources of unexplained NPFs in regions with high FA concentrations, such as densely forested areas with abundant vegetation, regions affected by biomass burning, or periods with elevated vehicle exhaust emissions and the release of volatile organic compounds like isoprene and terpenoids.

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A Robust Path Following Controller for a Small Unmanned Aerial Vehicle with Constrained Parameters Optimized

A Robust Path Following Controller for a Small Unmanned Aeri...

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International Conference on Information science and Control Engineering (ICISCE)

作者： Yang Chen Chaolei Wang School of Mechanical and Electrical Engineering Longyan University Longyan China Science and Technology on Special System Simulation Laboratory Beijing Simulation Center Beijing China

ISBN: (纸本)9781509025367

This paper proposes a nonlinear controller that allows the unmanned air vehicle (UAV) to follow a predefined path. The controller only needs the information of the inertial speed of the UAV and the distance between the vehicle and the desired path. In order to improve the performance of the controller, a parameter of the controller is optimized by using the concept of model predictive control (MPC). Lyapunov stability arguments are used to demonstrate that the path following error will be regulated to zero, even in the presence of wind disturbances. simulation results in Matlab are given to show the effectiveness of the controller. The simulation results show that the proposed path following controller with parameter optimized by MPC (PLC_MPC) which takes the advantages of the predictive ability of the MPC and the simple structure of the normal path following controller (PLC) has better path following performance than that by using the PLC method.

关键词： Unmanned aerial vehicles Mathematical model Optimization Stability analysis Trajectory Lyapunov methods

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Cross-stacked super-aligned carbon nanotube/activated carbon composite electrodes for efficient water purification via capacitive deionization enhanced ultrafiltration

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Frontiers of Environmental science & Engineering 2020年第6期14卷 181-190页

作者： Min Li Shuai Liang Yang Wu Meiyue Yang Xia Huang Beijing Key Laboratory for Source Control Technology of Water Pollution College of Environmental Science and EngineeringBeijing Forestry UniversityBeijing 100083China Department of Mechanical Engineering and Tsinghua Foxconn Nanotechnology Research Center Tsinghua UniversityBeijing 100084China State Key Joint Laboratory of Environment Simulation and Pollution Control School of EnvironmentTsinghua UniversityBeijing 100084China

The practical application of the capacitive deionization(CDI)enhanced ultrafiltration(CUF)technology is hampered due to low performance of *** current study demonstrated a novel super-aligned carbon nanotube(SACNT)/activated carbon(AC)composite electrode,which was prepared through coating AC on a cross-stacked SACNT *** desalination capability and water purification performance of the prepared electrode were systematically investigated at different applied voltages(0.8-1.2 V)with a CDI system and a CUF system,*** the CDI tests,as compared with 5ie control AC electrode,the SACNT/AC electrode achieved an approximately 100%increase in both maximum salt adsorption capacity and average salt adsorption rate under all the applied voltage conditions,demonstrating a superior desalination ***,a conspicuous increase by an average of-26%in charge efficiency was also achieved at all the *** the CUF tests,as compared with the control run at 0 V,the treatment runs at 0.8,1.0,and 1.2 V achieved a 2.40-fold,2.08-fold,and 2.43-fold reduction in membrane fouling(calculated according to the final transmembrane pressure(TMP)data at the end of every purification stage),*** average TMP increasing rates at 0.8,1.0,and 1.2 V were also roughly two times smaller than that at 0 V,indicating a dramatical reduction of membrane *** SACNT/AC electrode also maintained its superior desalination capability in the CUF process,resulting in an overall improved water purification efficiency.

关键词： Carbon nanotube Super aligned Conductive membrane Capacitive deionization Ultrafiltration Desalination

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Open-source dataset of vehicle state for an electric vehicle on a low-adhesion road

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science China(Information sciences) 2022年第3期65卷 258-259页

作者： Shuo CAI Haitao DING Yunfeng HU Lin ZHANG Qin LI Hong CHEN State Key Laboratory of Automotive Simulation and Control Jilin University Department of Control Science and Engineering Jilin University School of Automotive Studies Tongji University Collaborative Innovation Center of Electric Vehicles in Beijing Beijing Institute of Technology GAC R&D Center

This study demonstrates and opens for academic research six sets of electric vehicle data collected during experiments on a low-adhesion road. The 11-dimensional data were collected from a small, single-motor SUV with front-wheel *** data collected for vehicles on low-adhesion roads are crucial for research on system dynamics modeling,stability control system design, and vehicle state estimation. Indeed, all vehicle control systems must be validated on low-adhesion roads, including vehicle models,

关键词： vehicle experimental data dynamics modeling state estimation control system design low adhesion road

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Air pollution characteristics and their relationship with emissions and meteorology in the Yangtze River Delta region during 2014–2016

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Journal of Environmental sciences 2019年第9期31卷 8-20页

作者： Tao Ma Fengkui Duan Kebin He Yu Qin Dan Tong Guannan Geng Xuyan Liu Hui Li Shuo Yang Siqi Ye Beiyao Xu Qiang Zhang Yongliang Ma State Key Joint Laboratory of Environment Simulation and Pollution Control School of Environment State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex Beijing Key Laboratory of Indoor Air Quality Evaluation and Control Tsinghua University Beijing 100084 China Ministry of Education Key Laboratory for Earth System Modeling Department of Earth System Science Tsinghua University Beijing 100084 China National Satellite Meteorological Center Beijing 100081 China College of Resources and Environmental Sciences China Agricultural University Beijing 100094 China

With rapid economic growth and urbanization, the Yangtze River Delta(YRD) region in China has experienced serious air pollution challenges. In this study, we analyzed the air pollution characteristics and their relationship with emissions and meteorology in the YRD region during 2014–2016. In recent years, the concentrations of all air pollutants, except O3,decreased. Spatially, the PM2.5, PM10, SO2, and CO concentrations were higher in the northern YRD region, and NO2 and O3 were higher in the central YRD region. Based on the number of non-attainment days(i.e., days with air quality index greater than 100), PM2.5 was the largest contributor to air pollution in the YRD region, followed by O3, PM10, and ***, particulate matter pollution has declined gradually, while O3 pollution *** conditions mainly influenced day-to-day variations in pollutant concentrations. PM2.5 concentration was inversely related to wind speed, while O3 concentration was positively correlated with temperature and negatively correlated with relative *** air quality improvement in recent years was mainly attributed to emission *** 2014–2016, PM2.5, PM10, SO2, NOx, CO, NH3, and volatile organic compound(VOC)emissions in the YRD region were reduced by 26.3%, 29.2%, 32.4%, 8.1%, 15.9%, 4.5%, and0.3%, respectively. Regional transport also contributed to the air pollution. During regional haze periods, pollutants from North China and East China aggravated the pollution in the YRD region. Our findings suggest that emission reduction and regional joint prevention and control helped to improve the air quality in the YRD region.

关键词： Air pollution Spatiotemporal variation Meteorological condition Emission inventory Regional transport Yangtze River Delta

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Fast direct solution of 3-D dynamic electromagnetic problems by method of moments

Fast direct solution of 3-D dynamic electromagnetic problems...

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Antennas and Propagation Society International Symposium

作者： Yan-Nan Liu Ming-Ming Xu Xiao-Min Pan Xin-Qing Sheng Cong-Jun Jin Center for Electromagnetic Simulation Beijing Institute of Technology Beijing China Science and Technology on Space System Simulation Laboratory Beijing China

The direct solver based on skeletonization consists of two stages: selecting skeletons and computing the inverse matrix. The selection of skeletons can be expensive although Huygens' principle is employed to avoid filling in the complete impedance matrix. A fast matrix filling strategy is proposed to alleviate the difficulty by making use of Taylor series. Numerical experiments indicate the proposed method can significantly accelerate the matrix filling process with no loss in accuracy.

关键词： Skeleton Method of moments Taylor series Electromagnetics Impedance Matrix decomposition Integral equations

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Occurrence and Decay of SARS-CoV-2 in Community Sewage Drainage systems

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Engineering 2023年第7期26卷 214-219,I0008,I0009页

作者： Qian Dong 蔡俊雄刘艳臣凌海波 Qi Wang Luo-Jing Xiang Shao-Lin Yang Zheng-Sheng Lu Yi Liu Xia Huang 曲久辉 State Key Joint Laboratory of Environment Simulation and Pollution Control School of EnvironmentTsinghua UniversityBeijing 100084China Hubei Provincial Academy of Eco-Environmental Sciences Wuhan 430072China Key Laboratory of Drinking Water Science and Technology Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China

The rapid spread of the coronavirus disease(COVID-19)pandemic in over 200 countries poses a substantial threat to human *** acute respiratory syndrome coronavirus 2(SARS-CoV-2),which causes COVID-19,can be discharged with feces into the drainage ***,a comprehensive understanding of the occurrence,presence,and potential transmission of SARS-CoV-2 in sewers,especially in community sewers,is still *** study investigated the virus occurrence by viral nucleic acid testing in vent stacks,septic tanks,and the main sewer outlets of community where confirmed patients had lived during the early days of the epidemic in Wuhan,*** results indicated that the risk of long-term emission of SARS-CoV-2 to the environment via vent stacks of buildings was low after confirmed patients were ***-CoV-2 were mainly detected in the liquid phase,as opposed to being detected in aerosols,and its RNA in the sewage of septic tanks could be detected for only four days after confirmed patients were *** surveillance of SARS-CoV-2 in sewage could be a sensitive indicator for the possible presence of asymptomatic patients in the community,though the viral concentration could be diluted more than ten times,depending on the sampling site,as indicated by the Escherichia coli *** comprehensive investigation of the community sewage drainage system is helpful to understand the occurrence characteristics of SARS-CoV-2 in sewage after excretion with feces and the feasibility of sewage surveillance for COVID-19 pandemic monitoring.

关键词： SARS-CoV-2 Transmission risk Drainage system Sewage Community

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A homogenization method for nonlinear inhomogeneous elastic materials

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Virtual Reality & Intelligent Hardware 2021年第2期3卷 156-170页

作者： Jing ZHAO Fei ZHU Liyou XU Yong TANG Sheng LI College of Information Science and Engineering Yanshan UniversityQinhuangdaoHebei 066004China The Key Laboratory for Computer Virtual Technology and System Integration of Hebei Province QinhuangdaoHebei 066004China School of Electronics Engineering and Computer Science Peking UniversityBeijing 100871China Beijing Engineering Research Center for Virtual Simulation and Visualization Beijing 100871China

Background Fast simulation techniques are strongly favored in computer graphics,especially for the nonlinear inhomogeneous elastic *** homogenization theory is a perfect match to simulate inhomogeneous deformable objects with its coarse discretization,as it reveals how to extract information at a fine scale and to perform efficient computation with much less *** existing homogenization method is not applicable for ubiquitous nonlinear materials with the limited input deformation *** In this paper,we have proposed a homogenization method for the efficient simulation of nonlinear inhomogeneous elastic *** approach allows for a faithful approximation of fine,heterogeneous nonlinear materials with very coarse *** analysis provides the basis of a linear deformation space and modal derivatives extend the space to a nonlinear regime;based on this,we exploited modal derivatives as the input characteristic deformations for *** also present a simple elastic material model that is nonlinear and anisotropic to represent the homogenized *** nonlinearity of material deformations can be represented properly with this *** material properties for the coarsened model were solved via a constrained optimization that minimizes the weighted sum of the strain energy deviations for all input deformation *** arbitrary number of bases can be used as inputs for homogenization,and greater weights are placed on the more important low-frequency *** Based on the experimental results,this study illustrates that the homogenized material properties obtained from our method approximate the original nonlinear material behavior much better than the existing homogenization method with linear displacements,and saves orders of magnitude of computational *** The proposed homogenization method for nonlinear inhomogeneous elastic materials is capable of capturing the nonlinear dynamics of the

关键词： Physical-based simulation Homogenization theory Heterogeneous material Modal basis

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