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Enhancement and Removal of PM_(2.5)by Cold and Warm Air Masses Accompanying Certain synoptic Weather systems across Hangzhou,China during 2014-2020

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Journal of Meteorological Research 2024年第3期38卷 620-634页

作者： Bu Yu feng CHEN Hanqing KANG Bin ZHu Hongnian LIu Hangzhou Meteorological Bureau Hangzhou310051China Hangzhou International urbanology Research Center for urban Governance s.udies Hangzhou311121China Zhejiang Institute of Meteorological sciences Hangzhou310008China Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration Nanjing University of Information Science&TechnologyNanjing210044China school of Atmospheric sciences Nanjing UniversityNanjing210023China

Local air pollution is strongly affected by synoptic weather systems,such as fronts,troughs,low-altitude vortices,or high-altitude ***,few s.udies have analyzed the meteorological properties of cold or warm air masses associated to these systems and their impact on local air *** this s.udy,hourly observations of fine particulate matter(diameter of up to 2.5µm,i.e.,PM_(2.5)),wind(V),temperature(T),pres.ure(P),and precipitation(R),acquired in Hangzhou in 2014-2020,were *** this analysis,weather patterns were categorized into 27 types;89 and 94 cases illustrating the passage of warm and cold air masses over Hangzhou were identified,respectively;the influence of air mass temperature,wind speed,and wind direction on PM_(2.5) concentrations and local accumulation or removal was *** main results are as follows.(1)Pollution events occurred more frequently for cold than for warm air masses,but average pollutant concentration was lower for cold air masses;(2)48%of the cold air mass cases corresponded to PM_(2.5) decreases and 52%to PM_(2.5) increases,with strong cold air masses(ΔT_(24h)>4°C;∣V∣_(average)>4 m s^(−1))markedly reducing local pollution,but weak cold air masses(ΔT24hs^(−1))primarily inducing pollutant transport and accumulation;(3)for warm air masses,PM_(2.5)accumulation or removal occurred in 60%and 40%of the cases,respectively:warm air masses(ΔT24h>4°C)reduced the PM_(2.5) concentration whereas weaker winds(∣V∣_(average)s^(−1))increased it;and(4)PM_(2.5) concentration decreased sharply within 4 h after the passage of strong cold air masses,but more gradually within 14 h after the passage of strong warm air *** results considerably improve the current understanding of the influence of cold and warm air masses on local pollution patterns.

关键词： weather type air mass enhancement removal meteorological condition

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A disk I/O optimized system for concurrent graph processing jobs

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Frontiers of Computer science 2024年第3期18卷 13-29页

作者： Xianghao Xu Fang WANG Hong JIANG Yongli CHENG Dan feng Peng FANG school of Computer science and Engineering Nanjing University of Science and TechnologyNanjing 210094China Wuhan National Laboratory for Optoelectronics Huazhong University of Science and TechnologyWuhan 430074China Department of Computer science&Engineering University of Texas at ArlingtonArlingtonTX 76019USA College of Computer and Data science Fuzhou UniversityFuzhou 350108China Zhejiang Lab Hangzhou 311121China

In order to analyze and process the large graphs with high cost efficiency,researchers have developed a number of out-of-core graph processing systems in recent years based on just one commodity *** the other hand,with the rapidly growing need of analyzing graphs in the real-world,graph processing systems have to efficiently handle massive concurrent graph processing(CGP)***,due to the inherent design for single graph processing job,existing out-of-core graph processing systems.usually incur unnecessary data accesses and severe competition of I/O bandwidth when handling the CGP *** this paper,we propose GraphCP,a disk I/O optimized out-of-core graph processing system that efficiently supports the processing of CGP *** proposes a benefit-aware sharing execution model to share the I/O access and processing of graph data among the CGP jobs and adaptively schedule the graph data loading based on the states of vertices,which efficiently overcomes above challenges faced by existing out-of-core graph processing ***,GraphCP adopts a dependency-based future-vertex updating model so as to reduce disk I/Os in the future *** addition,GraphCP organizes the graph data with a s.urce-sorted sub-Block graph representation for better processing capacity and I/O access *** evaluation results show that GraphCP is 20.5×and 8.9×faster than two out-of-core graph processing systems GridGraph and GraphZ,and 3.5×and 1.7×faster than two state-of-art concurrent graph processing systems seraph and GraphsO.

关键词： graph processing disk I/O concurrent jobs

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Time-synchronous-averaging-spectrum based on super-resolution analysis and application in bearing fault signal identification

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Journal of Zhejiang university-science A(Applied Physics & Engineering) 2024年第7期25卷 573-585页

作者： Zengle REN Yuan WANG Huiyue TANG Xin'an CHEN Wei feng Guangdong Provincial Key Laboratory of Construction Robotics and Intelligent Construction Shenzhen Institute of Advanced TechnologyChinese Academy of SciencesShenzhen518055China shenzhen EBORAIL Technology Co. Ltd.Shenzhen518038China National supercomputing Center in shenzhen Shenzhen518055China state Key Lab of Rail Traffic Control and safety Beijing Jiaotong UniversityBeijing100044China university of Chinese Academy of sciences Beijing100190China shenzhen university of Advanced Technology Shenzhen518107China

Time-synchronous-averaging(TsA)is based on the idea of denoising by averaging,and it extracts the periodic components of a quasiperiodic signal and keeps the extracted waveform *** paper s.udies the mathematical properties of TsA,where three propositions are given to reveal the nature of *** paper also proposes a TsA-spectrum based on super-resolution analysis and it decomposes a signal without using any base *** contrast to discrete Fourier transform spectrum(DFT-spectrum),which is a spectrum in frequency domain,TsA-spectrum is a period-based spectrum,which can present more details of the cross effects between different periodic components of a quasiperiodic ***,a case s.udy is carried out using bearing fault analysis to illustrate the performance of TsA-spectrum,where the rotation speed fluctuation of the shaft is estimated,which is about 0.12 ms *** extracted fault signals are presented and some insights are *** believe that this paper can provide new motivation for TsA-spectrum to be widely used in applications involving quasiperiodic signal processing(QsP).

关键词： Time-synchronous-averaging(TsA) spectrum Quasiperiodic signal processing(QsP) super-resolution analysis Bearingfaultdetection

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Characteristics and triggering mechanisms of early negative Indian Ocean Dipole

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Acta Oceanologica sinica 2024年第3期43卷 59-65页

作者： Yue Fang s.uangwen sun Yongcan Zu Jianhu Wang Lin feng First Institute of Oceanography and Key Laboratory of Marine Science and Numerical ModelingMinistry of Natural ResourcesQingdao 266061China Laboratory for Regional Oceanography and Numerical Modeling Qingdao Marine Science and Technology CenterQingdao 266237China shandong Key Laboratory of Marine science and Numerical Modeling Qingdao 266061China

Negative Indian Ocean Dipole(nIOD)can exert great impacts on global climate and can also strongly influence the climate in *** nIOD is a major type of nIOD,which can induce more pronounced climate anomalies in summer than La Niña-related ***,the characteristics and triggering mechanisms of early nIOD are *** results based on reanalysis datasets indicate that the early nIOD and La Niña-related nIOD are the two major types of nIOD,and the former accounts for over one third of all the nIOD events in the past six *** two types of nIODs are similar in their intensities,but are different in their spatial patterns and seasonal *** early nIOD,which develops in spring and peaks in summer,is one season earlier than the La Niña-related *** spatial pattern of the wind anomaly associated with early nIOD exhibits a winter monsoon-like pattern,with strong westerly anomalies in the equatorial Indian Ocean and eastly anomalies in the northern Indian *** to the triggering mechanism of early positve IOD,the early nIOD is induced by delayed Indian summer monsoon *** results of this s.udy are helpful for improving the prediction skill of IOD and its climate impacts.

关键词： Indian Ocean Dipole(IOD) triggering mechanism Indian summer monsoon seasonal cycle negative IOD

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simulation and analysis of soil homogenization drills based on discrete element method and response surface methodology

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Particuology 2024年第5期88卷 128-148页

作者： Zhipeng Wang Tong Zhu Youzhao Wang song Yang feng Ma Xu Li Institute of Process Equipment and Environmental Engineering School of Mechanical Engineering and AutomationNortheastern UniversityShenyang110819China Liaoning Coning Testing Co. Ltd.Shenyang110170 China

Currently,rotary drilling is one of the main pieces of equipment used for in-situ remediation of contaminated ***,this equipment has problems such as.uneven mixing and low utilization efficiency,which affect the efficiency of in-situ soil *** improve the efficiency of in-situ soil remediation,this paper takes contaminated black soil as the research object,and the structural design of the new three-stage soil remediation auger is carried out based on *** mixing process of soil and heavy metal passivator under different motion and structural parameters was investigated by the discrete element method(DEM)and response surface *** experimental design was based on rotational speed,homogenizing mixing time,crushing section pitch,and homogenizing section pitch as factors,and soil fragmentation ratio,the coefficient of dispersion,and torque as optimization *** kinematic and structural parameters of the three-stage auger drill bit were then optimized using the one-factor method,the orthogonal test,and the response surface methodology,*** test method uses a one-way test to determine the central level value of the orthogonal test and a comprehensive balance method to determine the best combination of parameters for the orthogonal test,which is then used as the central value of the response surface test for parameter *** optimal combinations of kinematic and structural parameters of the three-stage auger drill bit are determined and validated using response surface *** optimum combination of parameters was found to be a speed of 129 rpm,a homogenizing mixing time of 24 s,a pitch of 165 mm in the crushing section,and a pitch of 132 mm in the homogenizing *** error between the optimal value of the predicted model using the response surface method and the actual simulated value under the optimal parameters is 4.2%,4.9%,and 5.3%,*** optimized factor parameters provide a refe

关键词： Black soil Mixing homogeneity Orthogonal method Response surface methodology Discrete element method soil remediation

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Mechanism of internal thermal runaway propagation in blade batteries

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Journal of Energy Chemistry 2024年第2期89卷 184-194,I0005页

作者： Xuning feng Fangs.u Zhang Wensheng Huang Yong Peng Chengshan Xu Minggao Ouyang school of Vehicle and Mobility Tsinghua UniversityBeijing 100084China

Blade batteries are extensively used in electric vehicles,but unavoidable thermal runaway is an inherent threat to their safe *** s.udy experimentally investigated the mechanism underlying thermal runaway propagation within a blade battery by using a nail to trigger thermal runaway and thermocouples to track its propagation inside a *** results showed that the internal thermal runaway could propagate for up to 272 s,which is comparable to that of a traditional battery *** velocity of the thermal runaway propagation fluctuated between 1 and 8 mm s^(-1),depending on both the electrolyte content and high-temperature gas *** the early stages of thermal runaway,the electrolyte participated in the reaction,which intensified the thermal runaway and accelerated its *** the battery temperature increased,the electrolyte evaporated,which attenuated the acceleration *** diffusion affected thermal runaway propagation through both heat transfer and mass *** experimental results indicated that gas diffusion accelerated the velocity of thermal runaway propagation by 36.84%.We used a 1D mathematical model and confirmed that convective heat transfer induced by gas diffusion increased the velocity of thermal runaway propagation by 5.46%-17.06%.Finally,the temperature rate curve was analyzed,and a three-stage mechanism for internal thermal runaway propagation was *** stage I,convective heat transfer from electrolyte evaporation locally increased the temperature to 100℃.In stage II,solid heat transfer locally increases the temperature to trigger thermal *** stageⅢ,thermal runaway sharply increases the local *** proposed mechanism sheds light on the internal thermal runaway propagation of blade batteries and offers valuable insights into safety considerations for future design.

关键词： Lithium-ion battery Blade battery Thermal runaway Internal thermal runaway propagation

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A novel high-Cr CoNi-based superalloy with superior high-temperature microstructural stability, oxidation resistance and mechanical properties

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International Journal of Minerals,Metallurgy and Materials 2024年第6期31卷 1373-1381页

作者： Xiaorui Zhang Min Zou song Lu Longfei Li Xiaoli Zhuang Qiang feng Beijing Advanced Innovation Center for Materials Genome Engineering State Key Laboratory for Advanced MetalsUniversity of Science and Technology BeijingBeijing 100083China

A novel multicomponent high-Cr CoNi-based superalloy with superior comprehensive performance was prepared,and the evaluation of its high-temperature microstructural stability,oxidation resistance,and mechanical properties was conducted mainly using its cast polycrystalline *** results disclosed that the morphology of theγ′phase remained stable,and the coarsening rate was slow during the long-term aging at 900–1000℃.The activation energy forγ′precipitate coarsening of alloy 9CoNi-Cr was(402±51)kJ/mol,which is higher compared with those of CMsX-4 and some other Ni-based and Co-based ***,there was no indica-tion of the formation of topologically close-packed phases during this *** these factors demonstrated the superior microstructural stability of the *** mass gain of alloy 9CoNi-Cr was 0.6 mg/cm^(2) after oxidation at 1000℃ for 100 h,and the oxidation resistance was comparable to advanced Ni-based superalloys CMsX-4,which can be attributed to the formation of a continuous Al_(2)O_(3) protective ***,the compressive yield strength of this cast polycrystalline alloy at high temperatures is clearly higher than that of the conventional Ni-based cast superalloy and the compressive minimum creep rate at 950℃ is comparable to that of the conventional Ni-based cast superalloy,demonstrating the alloy’s good mechanical properties at high *** is partially because high Cr is bene-ficial in improving theγandγ′phase strengths of alloy 9CoNi-Cr.

关键词： CoNi-based superalloys microstructure coarsening oxidation mechanical properties

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Layered metastructure containing freely-designed local resonators for wave attenuation

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Defence Technology（防务技术） 2024年第2期32卷 23-31页

作者： Yu Li Huguang He Jiang feng Hailong Chen fengnian Jin Hualin Fan state Key Laboratory for Disaster Prevention&Mitigation of Explosion&Impact Army Engineering University of PLANanjing 210007China Rocket Force university of Engineering Xi'an 710025China Henan International Joint Laboratory of Dynamics of Impact and Disaster of Engineering structures Department of Civil EngineeringNanyang Institute of TechnologyNanyang 473004China Guangxi Key Laboratory of Disaster Prevention and Engineering safety and Key Laboratory of Disaster Prevention and Structural Safety of Ministry of EducationCollege of Civil Engineering and ArchitectureGuangxi UniversityNanning 530004China Research Center of Lightweight structures and Intelligent Manufacturing State Key Laboratory of Mechanics and Control of Mechanical StructuresNanjing University of Aeronautics and AstronauticsNanjing 210016China

Combining periodic layered structure with three-dimensional cylindrical local resonators,a hybrid metastructure with improved wave isolation ability was designed and investigated through theoretical and numerical *** metastructure is composed of periodic rubber layers and concrete layers embedded with three-dimensional resonators,which can be freely designed with multi local resonant frequencies to attenuate vibrations at required frequencies and widen the attenuation *** metastructure can also effectively attenuate seismic *** with layered rubber-based structures,the metastructure has more excellent wave attenuation effects with greater attenuation and wider bandgap.

关键词： Layered metastructure Local resonator Wave attenuation

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An intelligent control method based on artificial neural network for numerical flight simulation of the basic finner projectile with pitching maneuver

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Defence Technology（防务技术） 2024年第2期32卷 663-674页

作者： Yiming Liang Guangning Li Min Xu Junmin Zhao feng Hao Hongbo shi Northwestern Polytechnical university school of Astronautics Xi’an 710072China China North Industries Group Corporation No 203 Research Institute Xi’an 710065China

In this paper,an intelligent control method applying on numerical virtual flight is *** proposed algorithm is verified and evaluated by combining with the case of the basic finner projectile model and shows a good application ***,a numerical virtual flight simulation model based on overlapping dynamic mesh technology is *** order to verify the accuracy of the dynamic grid technology and the calculation of unsteady flow,a numerical simulation of the basic finner projectile without control is carried *** simulation results are in good agreement with the experiment data which shows that the algorithm used in this paper can also be used in the design and evaluation of the intelligent controller in the numerical virtual flight ***,combined with the real-time control requirements of aerodynamic,attitude and displacement parameters of the projectile during the flight process,the numerical simulations of the basic finner projectile’s pitch channel are carried out under the traditional PID(Proportional-Integral-Derivative)control strategy and the intelligent PID control strategy *** intelligent PID controller based on BP(Back Propagation)neural network can realize online learning and self-optimization of control parameters according to the acquired real-time flight *** with the traditional PID controller,the concerned control variable overshoot,rise time,transition time and steady state error and other performance indicators have been greatly improved,and the higher the learning efficiency or the inertia coefficient,the faster the system,the larger the overshoot,and the smaller the stability *** intelligent control method applying on numerical virtual flight is capable of solving the complicated unsteady motion and flow with the intelligent PID control strategy and has a strong promotion to engineering application.

关键词： Numerical virtual flight Intelligent control BP neural network PID Moving chimera grid

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Multi-exit self-distillation with appropriate teachers

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Frontiers of Information Technology & Electronic Engineering 2024年第4期25卷 585-599页

作者： Wujie suN Defang CHEN Can WANG Deshi YE Yan feng Chun CHEN College of Computer science and Technology Zhejiang UniversityHangzhou 310000China

Multi-exit architecture allows early-stop inference to reduce computational cost,which can be used in res.urce-constrained *** works combine the multi-exit architecture with self-distillation to simultaneously achieve high efficiency and decent performance at different network ***,existing methods mainly transfer knowledge from deep exits or a single ensemble to guide all exits,without considering that inappropriate learning gaps between s.udents and teachers may degrade the model performance,especially in shallow *** address this is.ue,we propose Multi-exit self-distillation with Appropriate TEachers(MATE)to provide diverse and appropriate teacher knowledge for each *** MATE,multiple ensemble teachers are obtained from all exits with different trainable *** exit subsequently receives knowledge from all teachers,while focusing mainly on its primary teacher to keep an appropriate gap for efficient knowledge *** this way,MATE achieves diversity in knowledge distillation while ensuring learning *** results on CIFAR-100,TinyImageNet,and three fine-grained datasets demonstrate that MATE consistently outperforms state-of-the-art multi-exit self-distillation methods with various network architectures.

关键词： Multi-exit architecture Knowledge distillation Learning gap

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