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One-year observation of the mixing states of oxygenated organics-containing single particles in Guangzhou,China

Frontiers of Environmental Science & Engineering 2024年第5期18卷 155-169页

作者： Liyuan mao Suxia Yang Xiaoya cheng Sulin Liu Duanying chen Zhen Zhou mei Li chenglei Pei Chunlei cheng Institute of Mass Spectrometry and Atmospheric Environment Guangdong Provincial Engineering Research Center for the On-line Source Apportionment System of Air PollutionJinan UniversityGuangzhou510632China Guangdong-Hongkong-Macao Joint Laboratory of Collaborative Innovation for Environmental Quality Guangzhou510632China Guangzhou Research Institute of Environment Protection Co. Ltd.Guangzhou510620China Guangzhou Ecological and Environmental Monitoring Center of Guangdong Province Guangzhou510030China State Key Laboratory of Marine Resource Utilization in South China Sea Hainan UniversityHaikou570228China State Key Laboratory of Loess and Quaternary Geology Institute of Earth EnvironmentChinese Academy SciencesXi’an710061China

Oxygenated organic molecules(OOMs)play an important role in the formation of secondary organic aerosols(SOAs),but the mixing states of OOMs are still unclear.This study investigates the mixing states of OOM-containing single particles from the measurements taken using a single particle aerosol mass spectrometer in Guangzhou,China in 2022.Generally,the particle counts of OOM particles and the mass concentration of secondary organic carbon(SOC)exhibited similar temporal trends throughout the entire year.The OOM particles were consistently enriched in secondary ions,including 16O−,26CN−,46NO2−,62NO3−,and 97HSO4−.In contrast,the number fractions and diurnal patterns of OOM particles among the total detected particles showed similar distributions in August and October;however,the SOC ratios in fine particulate matter were quite different,suggesting that there were different mixing states of single-particle oxygenated organics.In addition,further classification results indicated that the OOM particles were more aged in October than August,even though the SOC ratios were higher in August.Furthermore,the distribution of hydrocarbon fragments exhibited a notable decrease from January to October,emphasizing the more aged state of the organics in October.In addition,the sharp increase in elemental carbon(EC)-OOM particles in the afternoon in October suggests the potential role of EC in the aging process of organics.Overall,in contrast to the bulk analysis of SOC mass concentration,the mixing states of the OOM particles provide insights into the formation process of SOAs in field studies.

关键词： Oxygenated organics Single particles Mixing state Secondary formation Photochemistry

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Equilibrium Strategy of the Pursuit-Evasion Game in Three-Dimensional Space

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IEEE/CAA Journal of Automatica Sinica 2024年第2期11卷 446-458页

作者： Nuo chen Linjing Li Wenji mao School of Artificial Intelligence University of Chinese Academy of SciencesBeijing 100049 Institute of Automation Chinese Academy of SciencesBeijing 100190China

The pursuit-evasion game models the strategic interaction among players, attracting attention in many realistic scenarios, such as missile guidance, unmanned aerial vehicles, and target defense. Existing studies mainly concentrate on the cooperative pursuit of multiple players in two-dimensional pursuit-evasion games. However, these approaches can hardly be applied to practical situations where players usually move in three-dimensional space with a three-degree-of-freedom control. In this paper,we make the first attempt to investigate the equilibrium strategy of the realistic pursuit-evasion game, in which the pursuer follows a three-degree-of-freedom control, and the evader moves freely. First, we describe the pursuer's three-degree-of-freedom control and the evader's relative coordinate. We then rigorously derive the equilibrium strategy by solving the retrogressive path equation according to the Hamilton-Jacobi-Bellman-Isaacs(HJBI) method, which divides the pursuit-evasion process into the navigation and acceleration phases. Besides, we analyze the maximum allowable speed for the pursuer to capture the evader successfully and provide the strategy with which the evader can escape when the pursuer's speed exceeds the threshold. We further conduct comparison tests with various unilateral deviations to verify that the proposed strategy forms a Nash equilibrium.

关键词： Differential game equilibrium strategy pursuit-evasion game threedegree-of-freedom control

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Single image defogging via multi-exposure image fusion and detail enhancement

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Journal of Safety Science and Resilience 2024年第1期5卷 37-46页

作者： Wenjing mao Dezhi Zheng Minze chen Juqiang chen School of Information and Electronics Advanced Research Institute of Multidisciplinary ScienceBeijing Institute of TechnologyBeijing100081China Chinese Aeronautical Establishment Beijing100012China

Outdoor cameras play an important role in monitoring security and social governance.As a common weather phenomenon,haze can easily affect the quality of camera shooting,resulting in loss and distortion of image details.This paper proposes an improved multi-exposure image fusion defogging technique based on the artificial multi-exposure image fusion(AMEF)algorithm.First,the foggy image is adaptively exposed,and the fused image is subsequently obtained via multiple exposures.The fusion weight is determined by the saturation,contrast,and brightness.Finally,the image fused by a multi-scale Laplacian algorithm is enhanced with simple adaptive details to obtain a clearer defogging image.It is subjectively and objectively verified that this algorithm can obtain more image details and distinct picture colors without a priori information,effectively improving the defogging ability.

关键词： Image defogging Multi-scale fusion Laplacian pyramid Adaptive detail enhancement

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Impacts of information about COVID-19 on pig farmers'production willingness and behavior:Evidence from China

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Journal of Integrative Agriculture 2024年第4期23卷 1429-1441页

作者： Huan chen Lei mao Yuehua Zhang School of Public Affairs Zhejiang UniversityHangzhou 310058China School of Insurance Central University of Finance and EconomicsBeijing 100081China Innovation Center of Yangtze River Delta Zhejiang UniversityJiaxing 314100China

This paper examines the impacts of information about COVID-19 on pig farmers'production willingness by using endorsement experiments and follow-up surveys conducted in 2020 and 2021 in China.Our results show that,first,farmers were less willing to scale up production when they received information about COVID-19.The information in 2020 that the second wave of COVID-19 might occur without a vaccine reduced farmers'willingness to scale up by 13.4%,while the information in 2021 that COVID-19 might continue to spread despite the introduction of vaccine reduced farmers'willingness by 4.4%.Second,farmers whose production was affected by COVID-19 were considerably less willing to scale up,given the access to COVID-19 information.Third,farmers'production willingness can predict their actual production behavior.

关键词： COVID-19 randomized experiment information treatment production willingness

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Parametric resonance of axially functionally graded pipes conveying pulsating fluid

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Applied Mathematics and Mechanics(English Edition) 2024年第2期45卷 239-260页

作者： Jie JING Xiaoye mao Hu DING Liqun chen Shanghai Key Laboratory of Mechanics in Energy Engineering Shanghai Frontier Science Center of MechanoinformaticsShanghai Institute of Applied Mathematics and MechanicsSchool of Mechanics and Engineering ScienceShanghai UniversityShanghai 200444China Shanghai Institute of Aircraft Mechanics and Control Shanghai 200092China

Based on the generalized Hamilton's principle,the nonlinear governing equation of an axially functionally graded(AFG)pipe is established.The non-trivial equilibrium configuration is superposed by the modal functions of a simply supported beam.Via the direct multi-scale method,the response and stability boundary to the pulsating fluid velocity are solved analytically and verified by the differential quadrature element method(DQEM).The influence of Young's modulus gradient on the parametric resonance is investigated in the subcritical and supercritical regions.In general,the pipe in the supercritical region is more sensitive to the pulsating excitation.The nonlinearity changes from hard to soft,and the non-trivial equilibrium configuration introduces more frequency components to the vibration.Besides,the increasing Young's modulus gradient improves the critical pulsating flow velocity of the parametric resonance,and further enhances the stability of the system.In addition,when the temperature increases along the axial direction,reducing the gradient parameter can enhance the response asymmetry.This work further complements the theoretical analysis of pipes conveying pulsating fluid.

关键词： pipe conveying fluid axially functionally graded supercritical resonance multi-scale method parametric resonance

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The posterior selection method for hyperparameters in regularized least squares method

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Control Theory and Technology 2024年第2期22卷 184-194页

作者： Yanxin Zhang Jing chen Yawen mao Quanmin Zhu School of Science Jiangnan UniversityWuxi214122JiangsuChina The Science and Technology on Near-Surface Detection Laboratory Wuxi214122JiangsuChina Department of Engineering Design and Mathematics University of the West of EnglandBristolBS161QYUK

The selection of hyperparameters in regularized least squares plays an important role in large-scale system identification. The traditional methods for selecting hyperparameters are based on experience or marginal likelihood maximization method, which are inaccurate or computationally expensive. In this paper, two posterior methods are proposed to select hyperparameters based on different prior knowledge (constraints), which can obtain the optimal hyperparameters using the optimization theory. Moreover, we also give the theoretical optimal constraints, and verify its effectiveness. Numerical simulation shows that the hyperparameters and parameter vector estimate obtained by the proposed methods are the optimal ones.

关键词： Regularization method Hyperparameter System identification Least squares algorithm

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Cortical activity in patients with high-functioning ischemic stroke during the Purdue Pegboard Test:insights into bimanual coordinated fine motor skills with functional near-infrared spectroscopy

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Neural Regeneration Research 2024年第5期19卷 1098-1104页

作者： Siyun chen Mengchai mao Guangyue Zhu Yufeng chen Yuqi Qiu Bin Ye Dongsheng Xu The Second Rehabilitation Hospital of Shanghai ShanghaiChina College of Rehabilitation Science Shanghai University of Traditional Chinese MedicineShanghaiChina Engineering Research Center of Traditional Chinese Medicine Intelligent Rehabilitation Ministry of EducationShanghaiChina School of Statistics East China Normal UniversityShanghaiChina The Third Rehabilitation Hospital of Shanghai ShanghaiChina Tongji University ShanghaiChina Shuguang Hospital Affiliated to Shanghai University of Traditional Chinese Medicine ShanghaiChina

After stroke,even high-functioning individuals may experience compromised bimanual coordination and fine motor dexterity,leading to reduced functional independence.Bilateral arm training has been proposed as a promising intervention to address these deficits.However,the neural basis of the impairment of functional fine motor skills and their relationship to bimanual coordination performance in stroke patients remains unclear,limiting the development of more targeted interventions.To address this gap,our study employed functional near-infrared spectroscopy to investigate cortical responses in patients after stroke as they perform functional tasks that engage fine motor control and coordination.Twenty-four high-functioning patients with ischemic stroke(7 women,17 men;mean age 64.75±10.84 years)participated in this cross-sectional observational study and completed four subtasks from the Purdue Pegboard Test,which measures unimanual and bimanual finger and hand dexterity.We found significant bilateral activation of the sensorimotor cortices during all Purdue Pegboard Test subtasks,with bimanual tasks inducing higher cortical activation than the assembly subtask.Importantly,patients with better bimanual coordination exhibited lower cortical activation during the other three Purdue Pegboard Test subtasks.Notably,the observed neural response patterns varied depending on the specific subtask.In the unaffected hand task,the differences were primarily observed in the ipsilesional hemisphere.In contrast,the bilateral sensorimotor cortices and the contralesional hemisphere played a more prominent role in the bimanual task and assembly task,respectively.While significant correlations were found between cortical activation and unimanual tasks,no significant correlations were observed with bimanual tasks.This study provides insights into the neural basis of bimanual coordination and fine motor skills in high-functioning patients after stroke,highlighting task-dependent neural responses.The findings also suggest that patients wh

关键词： bilateral arm training bimanual coordination cortical activity fine motor dexterity functional near-infrared spectroscopy(fNIRS) high-functioning Purdue Pegboard Test stroke

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Simulation of RFI Cancellation Using Subspace Projection Algorithm for PAF Receiver

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Research in Astronomy and Astrophysics 2024年第1期24卷 237-244页

作者： Peng Wu Jian Li mao-Zheng chen Xinjiang Astronomical Observatory Chinese Academy of SciencesUrumqi 830011China University of Chinese Academy of Sciences Beijing 100049China Xinjiang Key Laboratory of Microwave Technology Urumqi 830011China

The simulation of radio frequency interference(RFI) cancellation by applying a spatial filtering technique for phased array feed(PAF) is presented. In order to better reflect the characteristics of PAF, a new signal model is to add the coupling coefficient among elements of PAF to the conventional array signal model. Then the subspace projection(SP) algorithm is used to cancel RFI from the correlation matrix of the signal, and finally, the 2D power image is drawn. The power variation of signal-of-interest direction and RFI direction before and after using the SP algorithm is analyzed. The new signal model and simulation strategy can be used to test and verify the beamformer.

关键词： methods:analytical techniques:radar astronomy telescopes

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Extraction of Valuable Metals from Titanium-bearing Blast Furnace Slag by Acid Leaching

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Journal of Wuhan University of Technology(Materials Science) 2024年第2期39卷 376-385页

作者：刘燕 chen Xuegui mao Shuaidong XIAO Yadong LI Jiacong School of Metallurgy Northeastern UniversityShenyang 110819China Key Laboratory of Ecological Metallurgy of Multi-metal Intergrown Ores of Ministry of Education Shenyang 110819China

To realize the resource utilization of the valuable metals in the titanium-containing blast furnace slag,the process route of “hydrochloric acid leaching-electrolysis-carbonization and carbon dioxide capture-preparation of calcium carbonate” was proposed.In this study,the influences of process conditions on the leaching rates of calcium,magnesium,aluminum,and iron and the phases of the leaching residue were investigated for the leaching process.The experimental results show that the HCl solution could selectively leach the elements from the titanium-containing blast furnace slag.The better leaching conditions are the HCl solution concentration of 4 mol/L,the leaching time of 30 min,the ratio of liquid volume to solid gas of 10 mL/g,and the stirring paddle speed of 300 r/min.Under the conditions,the leaching rates of calcium,magnesium,aluminum,and iron can reach 85.87%,73.41%,81.35%,and 59.08%,and the leaching rate of titanium is 10.71%.The iron and the aluminum are removed from the leachate to obtain iron-aluminum water purification agents,and the magnesium is removed from the leachate to obtain magnesium hydroxide.The leaching residue phase is dominated by perovskite,followed by magnesium silicate and tricalcium aluminate,and the titaniumrich material could be obtained from the leaching residue by desiliconization.

关键词： titanium-containing blast furnace slag acid leaching valuable metals comprehensive utilization

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THE TRUNCATED EM METHOD FOR JUMP-DIFFUSION SDDES WITH SUPER-LINEARLY GROWING DIFFUSION AND JUMP COEFFICIENTS

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Journal of Computational Mathematics 2024年第1期42卷 178-216页

作者： Shounian Deng chen Fei Weiyin Fei Xuerong mao Key Laboratory of Advanced Perception and Intelligent Control of High-end Equipment Ministry of Educationand School of Mathematics-Physics and FinanceAnhui Polytechnic UniversityWuhu 241000China Business School University of Shanghai for Science and TechnologyShanghai 200093China Department of Mathematics and Statistics University of StrathclydeGlasgow G11XHUK

This work is concerned with the convergence and stability of the truncated EulerMaruyama(EM)method for super-linear stochastic differential delay equations(SDDEs)with time-variable delay and Poisson jumps.By constructing appropriate truncated functions to control the super-linear growth of the original coefficients,we present two types of the truncated EM method for such jump-diffusion SDDEs with time-variable delay,which is proposed to be approximated by the value taken at the nearest grid points on the left of the delayed argument.The first type is proved to have a strong convergence order which is arbitrarily close to 1/2 in mean-square sense,under the Khasminskii-type,global monotonicity with U function and polynomial growth conditions.The second type is convergent in q-th(q<2)moment under the local Lipschitz plus generalized Khasminskii-type conditions.In addition,we show that the partially truncated EM method preserves the mean-square and H∞stabilities of the true solutions.Lastly,we carry out some numerical experiments to support the theoretical results.

关键词： SDDEs Truncated EM method Time-variable delay Poisson jumps

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