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Electron and configuration engineering of atomic Cu and multioxidated Cu_(2+1)O centers via gasifiable reductant strategy for efficient oxygen reduction toward Zn-air battery

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Nano Research 2023年第2期16卷 2383-2391页

作者： Hongbin Li jia-jia Zheng Mingfan Yang Jingui duan State Key Laboratory of Materials-Oriented Chemical Engineering College of Chemical EngineeringNanjing Tech UniversityNanjing 211816China Laboratory of Theoretical and Computational Nanoscience National Center for Nanoscience and TechnologyChinese Academy of SciencesBeijing 100190China

Efforts in a large number of transition metal-carbon systems are devoted to the development of efficient catalysts for oxygen reduction reaction(ORR).However,unsatisfied O_(2)adsorption and slow reduction of OH*at the active centers hinder the further development of these catalysts.We here report a gasifiable reductant strategy,of which a new Cu-based metal organic framework(MOF:termed NTU-83)nanosheet was co-pyrolyzed with melamine to produce the N-coordinated atomic Cu and multi-oxidated Cu_(2+1)O active centers on the carbon foam with ultrathin skeleton.The engineered electrons and configuration of the active centers boost the catalyst(Cu/NC-1000)to show superior ORR activity(E_(1/2)=0.85 V),excellent stability,and methanol resistance.Further modeling calculation and controlled experiments reveal that the Cu_(2+1)O species play a crucial role in kinetically accelerated adsorption and activation of O_(2),while the N_(4)coordinated atomic Cu facilitates fast reduction of OH*.Such characteristics endow the Zn-air battery that containing Cu/NC-1000 as air cathode to show a high peak power density(138 mW·cm^(−2)),a high specific capacity of 763 mAh·gZn^(−1),and outstanding long-term cycle stability.The plausible mechanism and excellent performance show that gasifiable reductant strategy opens up a new route for regulation of the electronic of active sites but also provides a candidate for the practical application in energy conversion/storage devices.

关键词： metal organic framework nanosheet carbon foam atomic Cu Cu_(2+1)O nanosheet electron and configuration engineering

Fixed-Time Cluster Optimization for Multi-Agent Systems Based on Piecewise Power-Law Design

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IEEE/CAA Journal of Automatica Sinica 2024年第5期11卷 1301-1303页

作者： Suna duan Xinchun jia Xiaobo Chi School of Mathematical Sciences Shanxi UniversityTaiyuan 030006China School of Automation and Software Engineering Shanxi UniversityTaiyuan 030013China

Dear Editor,This letter focuses on the fixed-time(FXT)cluster optimization problem of first-order multi-agent systems(FOMASs)in an undirected network,in which the optimization objective is the sum of the objective functions of all clusters.A novel piecewise power-law control protocol with cooperative-competition relations is proposed.Furthermore,a sufficient condition is obtained to ensure that the FOMASs achieve the cluster consensus within an FXT.

关键词： agent cluster optimization

Classification of birds and drones by exploiting periodical motions in Doppler spectrum series

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Journal of Systems Engineering and Electronics 2023年第1期34卷 19-27页

作者： DUAN Jia ZHANG Lei WU Yifeng ZHANG Yue ZHAO Zeya GUO Xinrong School of Electronics and Communication Sun Yat-Sen UniversityShenzhen 518107China Beijing Institute of Tracking and Telecommunication Technology Beijing 100854China Armed Police Engineering University Xi’an 510507China

With the rapidly growing abuse of drones, monitoring and classification of birds and drones have become a crucial safety issue. With similar low radar cross sections(RCSs), velocities, and heights, drones are usually difficult to be distinguished from birds in radar measurements. In this paper, we propose to exploit different periodical motions of birds and drones from highresolution Doppler spectrum sequences(DSSs) for classification.This paper presents an elaborate feature vector representing the periodic fluctuations of RCS and micro kinematics. Fed by the Doppler spectrum and feature sequence, the long to short-time memory(LSTM) is used to solve the time series classification.Different classification schemes to exploit the Doppler spectrum series are validated and compared by extensive real-data experiments, which confirms the effectiveness and superiorities of the proposed algorithm.

关键词： target classification long-to-short memory(LSTM) drone discrimination Doppler spectrum series

Comparison of electrochemical behaviors of Ti-5Al-2Sn-4Zr-4Mo-2Cr-1Fe and Ti-6Al-4V titanium alloys in NaNO_(3) solution

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International Journal of Minerals,Metallurgy and Materials 2024年第4期31卷 750-763页

作者： jia Liu Shuanglu duan Xiaokang Yue Ningsong Qu College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China

The Ti-5Al-2Sn-4Zr-4Mo-2Cr-1Fe(β-CEZ)alloy is considered as a potential structural material in the aviation industry due to its outstanding strength and corrosion resistance.Electrochemical machining(ECM)is an efficient and low-cost technology for manufacturing theβ-CEZ alloy.In ECM,the machining parameter selection and tool design are based on the electrochemical dissolution behavior of the materials.In this study,the electrochemical dissolution behaviors of theβ-CEZ and Ti-6Al-4V(TC4)alloys in NaNO3solution are discussed.The open circuit potential(OCP),Tafel polarization,potentiodynamic polarization,electrochemical impedance spectroscopy(EIS),and current efficiency curves of theβ-CEZ and TC4 alloys are analyzed.The results show that,compared to the TC4 alloy,the passivation film structure is denser and the charge transfer resistance in the dissolution process is greater for theβ-CEZ alloy.Moreover,the dissolved surface morphology of the two titanium-based alloys under different current densities are analyzed.Under low current densities,theβ-CEZ alloy surface comprises dissolution pits and dissolved products,while the TC4 alloy surface comprises a porous honeycomb structure.Under high current densities,the surface waviness of both the alloys improves and the TC4 alloy surface is flatter and smoother than theβ-CEZ alloy surface.Finally,the electrochemical dissolution models ofβ-CEZ and TC4 alloys are proposed.

关键词： electrochemical machining dissolution behavior β-CEZ titanium alloy polarization curve current efficiency

Impact of Media Information on Social Response in Disasters:A Case Study of the Freezing‑Rain and Snowstorm Disasters in Southern China in 2008

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International Journal of Disaster Risk Science 2024年第1期15卷 73-87页

作者： jia He Wenjing duan Yuxuan Zhou Yun Su College of Geographic Science and Tourism Xinjiang Normal UniversityUrumqi 830054China Xinjiang Laboratory of Lake Environment and Resources in Arid Zone Urumqi 830054China Faculty of Geographical Science Beijing Normal UniversityBeijing 100875China Key Laboratory of Environmental Change and Natural Disaster Ministry of EducationBeijing Normal UniversityBeijing 100875China

Disaster information content is an objective mapping of disaster situations,social response,and public opinions.Social response to emergency is an important mechanism for implementing and guaranteeing emergency management of major natural hazard-related disasters.Understanding how disaster information content affects social response to emergencies is helpful for managing risk communication and efficient disaster response.Based on the 2008 freezing-rain and snowstorm disasters in southern China,this study used Python to extract 7,857 case-related media reports and applied natural language processing for text analysis.It used three typical cases to identify and analyze disaster media report content and the relationship between these reports and the social response to the emergency.Eight categories of disaster response-such as prewarning and forecasting,announcements by the authorities,and social mobilization-appeared in the disaster information in the media,along with disaster impact information,that is,real-time disaster status.Disaster response information and an appropriate amount of disaster impact information played important roles in prewarning,disaster relief,public opinion guidance,and social stability maintenance and can serve important functions in communicating with all stakeholders of emergency management,assisting or influencing emergency departments or individuals in decision making,and eliminating "information islands." Empathy caused the general public to become "disaster responders" through receiving information.Rumors and an excess of negative information may have a perverse amplification effect on public opinion and increase the unpredictability of the disaster situation and the risk of social crisis.

关键词： Emergency management Freezing-rain and snowstorm disasters Media reports on disasters Social response to emergencies China

Efficient adsorption to hexavalent chromium by iron oxalate modified D301:Characterization,performance and mechanisms

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Chinese Journal of Chemical Engineering 2021年第5期34卷 61-69页

作者： Dongmei jia Huamin Cai Yongzheng duan jiangbao Xia jia Guo School of Chemical Engineering and Safety Binzhou UniversityBinzhou 256603China School of Chemical Engineering and Pharmaceutical Wuhan Institute of TechnologyWuhan 430073China Shandong Key Laboratory of Eco-Environmental Science for the Yellow River Delta Binzhou UniversityBinzhou 256603China

Chromium is a common harmful pollutant with high toxicity and low bearing capacity of soil and water.Excellent salinity resistance,a wide pH range,and high regeneration capacity were essential for qualified adsorbents used in removing hexavalent chromium(Cr(VI))from polluted water.Herein,iron oxalate modified weak basic resin(IO@D301)for the removal of Cr(VI)was prepared by the impregnation method.The IO@D301 was characterized by scanning electron microscope(SEM),Fourier transform infrared spectroscopy(FTIR),X-Ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS).Owing to abundant amine,carboxyl groups and iron ions existing on the surface,IO@D301 possesses high adsorption and salinity resistance capacity for Cr(VI).The maximum adsorption capacity of IO301 towards Cr(VI)reached 201.30 mg·g^(-1) at 293 K and a pH of 5.The adsorption equilibrium was well fitted by the Freundlich model,and the adsorption process was described by the pseudofirst-order kinetics model as spontaneous and exothermic.The mechanism may be identified as electrostatic attraction,coordination,and reduction,which was confirmed by FT-IR and X-ray photoelectron spectroscopy.

关键词： D301 Iron oxalate Chromium Adsorption

Suppression of self-sustained oscillations of incompressible flow over aperture-cavities and its mechanisms

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Journal of Hydrodynamics 2022年第5期34卷 876-892页

作者： Wen-wen Zhang Rong-wu Xu Lin He jia duan Institute of Vibration and Sound Naval University of EngineeringWuhan430033China National Key Laboratory on Ship Vibration and Noise Naval University of EngineeringWuhan430033China

Experiments and large-eddy simulations(LESs)are conducted to study the effectiveness and the underlying physical mechanisms of a passive control technique for suppressing the self-sustained oscillations of incompressible flow over aperture-cavities.The control technique is implemented by installing a wedge block above the chamfered leading-edge.The experiments are carried out in a low-speed water tunnel with the freestream velocity ranging from 0.4 m/s to 4.4 m/s,while the large-eddy simulations are carried out corresponding to the experiment at a velocity of 4.0 m/s.The wall pressure fluctuations measured along the cavity floor show that a significant suppression of the self-sustained oscillations of the shear layers can be achieved by the control device.Furthermore,the suppression performance is improved as the freestream velocity increases,not limited to the design point of the control device.The analysis of numerical simulation results focuses on three aspects,the vorticity fields,the velocity fields and the pressure fields,and the physical effects of the control device on the incompressible aperture-cavity flow are visualized.Three mechanisms of suppressing the cavity oscillations are identified from the numerical results,which are the destruction of the large vortex structures by the high frequency vortical excitations,the inhabitation of the intracavity recirculation feedback by introducing the lower shunt flow,and the attenuation of the trailing-edge impingement by thickening the shear layer.

关键词： Cavity oscillations flow control flow-induced noise numerical simulations hydrodynamic noise

Accurate prediction of air quality response to emissions for effective control policy design

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Journal of Environmental Sciences 2023年第1期123卷 116-126页

作者： Min Cao jia Xing Shovan Kumar Sahu Lei duan Junhua Li State Key Joint Laboratory of Environmental Simulation and Pollution Control School of EnvironmentTsinghua UniversityBeijing 100084China State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex Beijing 100084China

Designing effective control policy requires accurate quantification of the relationship between the ambient concentrations of O3and PM2.5and the emissions of their precursors.However,the challenge is that precursor reduction does not necessarily lead to decreases in the concentrations of O3and PM2.5,which are formed by multiple precursors under complex physical and chemical processes;this calls for the development of advanced model technologies to provide accurate predictions of the nonlinear responses of air quality to emissions.Different from the traditional sensitivity analysis and source apportionment methods,the reduced form models(RFMs)based on chemical transport models(CTMs)are able to quantify air quality responses to emissions more accurately and efficiently with lower computational cost.Here we review recent approaches used in RFMs and compare their structures,advantages and disadvantages,performance and applications.In general,RFMs are classified into three types including(1)sensitivity-based models,(2)models with simplified chemistry and physical processes,and(3)statistical models,with considerable differences in principles,characteristics and application ranges.The prediction of nonlinear responses by RFMs enables more in-depth analysis,not only in terms of real-time prediction of concentrations and quantification of human exposure,health impacts and economic damage,but also in optimizing control policies.Notably,data assimilation and emission inventory inversion based on the nonlinear response of concentrations to emissions can also be greatly beneficial to air pollution control management.In future studies,improvement in the performance of CTMs is exceedingly crucial to obtain a more reliable baseline for the prediction of air quality responses.Development of models to determine the air quality response to emissions under varying meteorological conditions is also necessary in the context of future climate changes,which pose great challenges to the quantification of response relationships.Additional

关键词： Air pollution Nonlinear response Air quality management Reduced form models(RFMs) Precursor emissions

Evaluation of Tianji and ECMWF high-resolution precipitation forecasts for extreme rainfall event in Henan in July 2021

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Water Science and Engineering 2023年第2期16卷 122-131页

作者： Wen-tao Li jia-peng Zhang Ruo-chen Sun Qingyun duan State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai UniversityNanjing 210098China College of Hydrology and Water Resources Hohai UniversityNanjing 210098China CMA-HHU Joint Laboratory for Hydrometeorological Studies Hohai UniversityNanjing 210098China

The extreme rainfall event of July 17 to 22, 2021 in Henan Province, China, led to severe urban waterlogging and flood disasters. This study investigated the performance of high-resolution weather forecasts in predicting this extreme event and the feasibility of weather forecast-based hydrological forecasts. To achieve this goal, high-resolution precipitation forecasts from the Tianji weather system and the forecast system of the European Centre for Medium-Range Weather Forecasts (ECMWF) were evaluated with the spatial verification metrics of structure, amplitude, and location. The results showed that Tianji weather forecasts accurately predicted the amplitude of 12-h accumulated precipitation with a lead time of 12 h. The location and structure of the rainfall areas in Tianji forecasts were closer to the observations than ECMWF forecasts. Tianji hourly precipitation forecasts were also more accurate than ECMWF hourly forecasts, especially at lead times shorter than 8 h. The precipitation forecasts were used as the inputs to a hydrological model to evaluate their hydrological applications. The results showed that the runoff forecasts driven by Tianji weather forecasts could effectively predict the extreme flood event. The runoff forecasts driven by Tianji forecasts were more accurate than those driven by ECMWF forecasts in terms of amplitude and location. This study demonstrates that high-resolution weather forecasts and corresponding hydrological forecasts can provide valuable information in advance for disaster warnings and leave time for people to act on the event. The results encourage further hydrological applications of high-resolution weather forecasts, such as Tianji weather forecasts, in the future.

关键词： Extreme precipitation High-resolution weather forecast Evaluation Flood forecasting Spatial forecast verification