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Electrospun Fe_(0.64)Ni_(0.36)/MXene/CNFs nanofibrous membranes with multicomponent heterostructures as flexible electromagnetic wave absorbers

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Nano Research 2023年第2期16卷 3395-3407页

作者： Shuo zhang Zirui Jia Yan Zhang Guanglei Wu Institute of Materials for Energy and Environment State Key Laboratory of Bio-fibers and Eco-textilesCollege of Materials Science and EngineeringQingdao UniversityQingdao 266071China College of Chemistry and Chemical Engineering Qingdao UniversityQingdao 266071China Weihai Innovation Institute Qingdao UniversityWeihai 264200China

Two-dimensional metal carbide or nitride materials(MXenes)are widely used in electromagnetic wave absorption because of their unique structure.Herein,a novel composite preparation strategy has been proposed to design dendritic nanofibers based on the electrostatic spinning methods.The multifunctional MXene nanosheets are used as the dendritic matrix,and magnetic nanoparticles are embedded in the nanosheets as magnetic loss units.Multidimensional nanocomposites have interlaced carbon fiber networks,large-scale magnetically coupled networks,and a lot of multi-heterojunction interface structures,which endow the composites with extraordinary conduction loss,magnetic loss,and polarization loss capabilities,respectively.The impedance matching and loss mechanisms of the composites are improved by optimizing the synergistic relationship between the components and building a suitable structure.The optimum reflection loss(RL)of−54.1 dB is achieved at 2.7 mm and a wide effective absorption bandwidth(EAB,RL below−10 dB)of 7.76 GHz is obtained at a small thickness of 2.1 mm for the nanocomposites.The distinctive microstructures of the nanofibrous membranes give rise to their flexibility,waterproof,and electromagnetic wave absorption performance and endow the nanofibrous membranes potential to be utilized as lightweight,efficient electromagnetic wave protective fabric in harsh environment.

关键词： MXene Fe_(0.64)Ni_(0.36) nanofibers electromagnetic wave absorption electrospinning

Design and In Situ Additive Manufacturing of Multifunctional Structures

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Engineering 2023年第9期28卷 58-68页

作者： Yan Zhang Guangyu zhang Jing Qiao Longqiu Li State Key Laboratory of Robotics and System Harbin Institute of TechnologyHarbin 150001China School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China

Multifunctional structures(MFSs)integrate diverse functions to achieve superior properties.However,conventional design and manufacturing methods—which generally lack quality control and largely depend on complex equipment with multiple stations to achieve the integration of distinct materials and devices—are unable to satisfy the requirements of MFS applications in emerging industries such as aerospace engineering.Motivated by the concept of design for manufacturing,we adopt a layer regulation method with an established optimization model to design typical MFSs with load-bearing,electric,heat-conduction,and radiation-shielding functions.A high-temperature in situ additive manufacturing(AM)technology is developed to print various metallic wires or carbon fiber-reinforced high-meltingpoint polyetheretherketone(PEEK)composites.It is found that the MFS,despite its low mass,exceeds the stiffness of the PEEK substrate by 21.5%.The embedded electrics remain functional after the elastic deformation stage.Compared with those of the PEEK substrate,the equivalent thermal conductivity of the MFS beneath the central heat source area is enhanced by 568.0%,and the radiation shielding is improved by 27.9%.Moreover,a satellite prototype with diverse MFSs is rapidly constructed as an illustration.This work provides a systematic approach for high-performance design and advanced manufacturing,which exhibits considerable prospects for both the function expansion and performance enhancement of industrial equipment.

关键词： Additive manufacturing Multifunctional structure Optimal design Satellite Polyetheretherketone

Geochronological and geochemical constraints on the petrogenesis and geodynamic process of Hemler,Vlinder,and Il'ichev seamount lavas in NW Pacific

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Science China Earth Sciences 2024年第6期67卷 1856-1871页

作者： Xun WEI Yan Zhang Xuefa SHI Hui zhang Key Laboratory of Marine Geology and Metallogeny First Institute of OceanographyMinistry of Natural ResourcesQingdao 266061China Laboratory for Marine Geology Qingdao Marine Science and Technology CenterQingdao 266237China Shandong Key Laboratory of Deep Sea Mineral Resources Development(Preparatory) Qingdao 266061China

Oceanic intraplate volcanoes with linear age progressions are usually accepted to be derived from melting of an upwelling mantle plume.Several seamount groups in NW Pacific,however,show complex age-distance relationships that are difficult to explain using the classic“mantle plume hypothesis”,and thus their origins are controversial.In this study,we present ^(40)Ar-^(39)Ar age,geochemical,and Sr-Nd-Pb-Hf isotopic data of lavas from Hemler,Vlinder,and Il’ichev seamounts in NW Pacific,to elucidate their petrogenesis and geodynamic process.The lavas from Hemler,Vlinder,and Il’ichev seamounts are classified as alkali basalt,basanite/nephelinite,and trachyte.Lavas with Mg O>8 wt.%exhibit high contents of CaO,FeO^(T),and TiO_(2),similar to the composition of melts formed from reaction between carbonated eclogite-derived melts and fertile peridotite.These lavas have elevated Zr/Hf ratios(40.6-45.2)and negative Zr and Hf anomalies,indicating the presence of a carbonate component in the mantle source.They are enriched in incompatible trace elements and have enriched mantle 1(EM1)-like SrNd-Pb-Hf isotopic compositions.The isotopic compositions of Vlinder,Il’ichev basanite,and Hemler lavas in this study are similar to the Rarotonga hotspot.Although occurring at the same seamount,the Il’ichev alkali basalts display more depleted SrNd-Hf isotopic compositions compared to Il’ichev basanite.According to plate tectonic reconstruction results,the ages of Hemler(100.1 Ma),Vlinder pre-(100.2 Ma)and post-shield(87.5 Ma),and Il’ichev(56.4 Ma)lavas clearly deviate from the Macdonald,Arago,Rarotonga,and Samoa hotspot tracks,indicating that they cannot directly originate from mantle plumes.We propose that in the mid-Cretaceous,when the Pacific plate passed over Rarotonga hotspot,melting of Rarotonga plume formed the Vlinder(main-shield stage),Pako,and Ioah seamounts.The Rarotonga(and possibly Samoa)plume materials would have been dispersed into the surrounding asthenosphere by mantle convection.These diffuse plume materials would underg

关键词： Mantle plume Magellan seamount trail Carbonated mantle component Hotspot Lithosphere extension

Adaptive Digital Twin for Vehicular Edge Computing and Networks

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Journal of Communications and Information Networks 2022年第1期7卷 48-59页

作者： Yueyue Dai Yan Zhang School of Cyber Science and Engineering and Research Center of 6G Mobile Communications Huazhong University of Science and TechnologyWuhan 430000China Department of Informatics University of Oslo0316 OsloNorway

To better support the emerging vehicular applications and multimedia services,vehicular edge computing(VEC)provides computing and caching services in proximity to vehicles, by reducing network transmission latency and alleviating network congestion. However, current VEC networks may face some implementation challenges, such as high mobility of vehicles, dynamic vehicular environment,and complex network scheduling. Digital twin, as an emerging technology, can make the virtual representation of physical networks to predict, estimate,and analyze the real-time network state. In this paper, we integrate digital twin into VEC networks to adaptively make network management and policy schedule. We first introduce the framework of VEC networks and present the key problems in a VEC network.Next,we give the concept of digital twin and propose an adaptive digital twin-enabled VEC network. In the proposed network, digital twin can enable adaptive network management via the two-closed loops between physical VEC networks and digital twins. Further,we propose a digital twin empowered VEC offloading problem with vehicle digital models and road side unit (RSU) digital models. A deep reinforcement learning (DRL)-based offloading scheme is designed to minimize the total offloading latency. Numerical results demonstrate the effectiveness of the proposed DRL-based algorithm for VEC offloading.

关键词： adaptive digital twin vehicular edge computing deep reinforcement learning

Multi–physical-field characteristics modeling and structure optimization for kW-level ultra-high-speed PM motors with integrated support system

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Chinese Journal of Aeronautics 2023年第4期36卷 455-467页

作者： Qixing GAO Xiaolin WANG Yan Zhang College of Automation Engineering Nanjing University of Aeronautics and AstronauticsNanjing 211106China School of Intelligence Science and Control Engineering Jinling Institute of TechnologyNanjing 211169China

In the aerospace industry,the low-mass ultra-high-speed flywheel system play a critical role.In this paper,a kW-level Ultra-High Speed Permanent Magnet Synchronous Motor(UHSPMSM)as the core component of flywheel system is proposed and analyzed with consideration of multiple physical fields,including electromagnetic characteristics,mechanical strength and rotor dynamics.The integrated support structure is put forward to improve rotation accuracy and operation stability of the UHSPMSM.Further,influence of the integrated support structure on critical speed is explored,and the key parameters such as support position and support stiffness are designed.Moreover,the rotor strength is analyzed by analytical model developed of rotor stress that can deal with multiple boundary types.Material and thickness of the sleeve are optimized,and range of interference value is accurately limited based on four extreme operating conditions.The 3-D Finite Element Model(FEM)is used to validate the strength characteristics and stress distribu-tion of rotor.A 1.5 kW-150000 r/min UHSPMSM with integrated support system is manufactured and tested.The feasibility of UHSPMSM proposed and the accuracy of analysis method are verified through electromagnetic,temperature rise and vibration characteristics test.The machine prototype realizes the load operation at rated speed and the multi-physical-field characteristics achieve the design specification.

关键词： Flywheel energy storage Integrated support system Multi–physical-field charac-teristics Mechanical strength Rotor dynamics Ultra-high-speed motor

Construction of hierarchical In_(2)O_(3)/In_(2)S_(3) microsphere heterostructures for TEA detection

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Journal of Materiomics 2022年第6期8卷 1113-1121页

作者： Yongjie zhang Cong Qin Run zhang Yan Zhang yan Wang Zhanying zhang Jianliang Cao College of Chemistry and Chemical Engineering Henan Polytechnic UniversityJiaozuo454000China State Collaborative Innovation Center of Coal Work Safety and Clean-efficiency Utilization Henan Polytechnic UniversityJiaozuo454000China

Construction of heterojunction has been considered as an efficient strategy to enhance the gas-sensing performances of metal oxide semiconductors.On this basis,hierarchical In_(2)O_(3)/In_(2)S_(3) microsphere heterostructures were synthesized by partial oxidation of In_(2)S_(3) precursors which were obtained via a facile hydrothermal method.Besides,gas sensors based on the acquired materials were fabricated to investigate their sensing performances toward triethylamine(TEA).The results reveal that the gas sensor based on In_(2)O_(3)/In_(2)S_(3) exhibits a high response of 37 at 300℃ toward 0.45 mg/L TEA,which is 3.7 times higher than that of bare In_(2)O_(3).Meanwhile,it also possesses fast response/recovery time(19 s/154 s),good repeatability,selectivity and long-term stability.The excellent sensing performances toward TEA are mainly attributed to the massive oxygen vacancy defects and heterojunction formed between In_(2)O_(3) and In_(2)S_(3).This work provides a facile temperature-dependent route to controllably synthesize hierarchical In_(2)O_(3)/In_(2)S_(3) microsphere heterostructures,and the In_(2)O_(3)/In_(2)S_(3) sensor shows great application prospects in TEA detection.

关键词： In_(2)O_(3)/In_(2)S_(3) Heterojunction Hierarchical structure Triethylamine Gas sensor

Bifurcation analysis and optimal control of COVID-19 with exogenous reinfection and media coverages

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International Journal of Biomathematics 2023年第3期16卷 83-118页

作者： Jiajia zhang Yuanhua Qiao Yan Zhang Faculty of Science Beijing University of Technology Beijing 100124P.R.China

In this paper,a SEIR epidemic model related to media coverage and exogenous reinfections is established to explore the transmission dynamics of COVID-19.The basic reproduction number is calculated using the next generation matrix method.First,the existence of equilibrium points is investigated,and different kinds of equilibrium points indicate that the disease may disappear,or exist that result in different quantity of susceptible individuals,pre-symptomatic infected individuals and symptomatic infected individuals.The stability of the equilibria is discussed by a geometric approach,and it is found that controlling reproduction number to be lower than 1 is not suficient for eradication of COVID-19.Second,transcritical bifurcation is explored,and it is found that improving the ratio of exogenous reinfection may lead to backward bifurcation under poor medical conditions,which indicates that two endemic equilibrium points appear.Third,to investigate the infuence of parameters on the basic reproduction,sensitivity analysis is done to choose relatively sensitive parameters,and the parameters for treatment and media coverage are selected.An optimal control model is established to balance the treatment and media awareness.By exploring the existence and the uniqueness of the optimal control solution,the optimal control strategies are given.Finally,we run numerical simulations to verify the theoretical analysis on actual data of China,and the data from the four different states of India is used for forecasting the situation of infected individuals in a short period.It is found by the simulation that the co-function of treatment and media coverage results in the reduced number of infectious individuals.

关键词： COVID-19 backward bifurcation globally stable optimal control

Improved Generative Adversarial Behavioral Learning Method for Demand Response and Its Application in Hourly Electricity Price Optimization

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Journal of Modern Power Systems and Clean Energy 2022年第5期10卷 1358-1373页

作者： Junhao Lin Yan Zhang Shuangdie Xu Shanghai Jiao Tong University ShanghaiChina Shibei Electricity Supply Company State Grid Shanghai Municipal Electric Power CompanyShanghaiChina

In response to the imbalance between power generation and demand, demand response(DR) projects are vigorously promoted. However, customers’ DR behaviors are still difficult to be simulated accurately and objectively. To tackle this challenge, we propose a new DR behavioral learning method based on a generative adversary network to learn customers’ DR habits. The proposed method is also extended to maximize the economic revenues of generated DR policies on the premise of obeying customers’ DR habits, which is hard to be realized simultaneously by existing model-based methods and traditional learning-based methods. To further consider customers’ timevarying DR patterns and trace the changes dynamically, we define customers’ DR participation positivity as an indicator of their DR pattern and propose a condition regulation approach improving the natural generative adversary framework to generate DR policies conforming to customers’ current DR patterns. The proposed method is applied to hourly electricity price optimization to reduce the fluctuation of system aggregate loads. An online parameter updating method is also utilized to train the proposed behavioral learning model in continuous DR simulations during electricity price optimization. Finally, numerical simulations are conducted to verify the effectiveness and superiority of the proposed method.

关键词： Demand response behavioral learning reinforcement learning generative adversarial network electricity price optimization

Investigation of formaldehyde sources and its relative emission intensity in shipping channel environment

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Journal of Environmental Sciences 2024年第8期142卷 142-154页

作者： Jiaqi Liu Shanshan Wang Yan Zhang Yuhao yan Jian Zhu Sanbao zhang Tianyu Wang Yibing Tan Bin Zhou Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention(LAP3) Department of Environmental Science and EngineeringFudan UniversityShanghai 200433China Institute of Eco-Chongming(IEC) No.20 Cuiniao RoadShanghai 202162China Institute of Atmospheric Sciences Fudan UniversityShanghai 200433China National Observations and Research Station for Wetland Ecosystems of the yangtze Estuary Fudan UniversityShanghai 200438China Institute of Digitalized Sustainable Transformation Big Data InstituteFudan UniversityShanghai 200433China

Formaldehyde(HCHO)is considered one of the most abundant gas-phase carbonyl compounds in the atmosphere,which can be directly emitted through transportation sources.Long-Path Differential Optical Absorption Spectroscopy(LP-DOAS)was used to observe HCHO in the river channel of Wusong Wharf in Shanghai,China for the whole year of 2019.Due to the impact of ship activity,the annual average HCHO level in the channel is about2.5 times higher than that in the nearby campus environment.To explain the sources of HCHO under different meteorological conditions,the tracer-pair of CO and O_(x)(NO_(2)+O_(3))was used on the clustered air masses.The results of the source appointment show that primary,secondary and background account for 24.14%(3.34±1.19 ppbv),44.78%(6.20±2.04ppbv)and 31.09%(4.31±2.33 ppbv)of the HCHO in the channel when the air masses were from the mixed direction of the city and channel,respectively.By performing background station subtraction at times of high primary HCHO values and resolving the plume peaks,directly emitted HCHO/NO_(2)in the channel environment and plume were determined to be mainly distributed between 0.2 and 0.3.General cargo ships with higher sailing speeds or main engine powers tend to have higher HCHO/NO_(2)levels.With the knowledge of NO_(2)(or NO_(x))emission levels from ships,this study may provide data support for the establishment of HCHO emission factors.

关键词： HCHO LP-DOAS Channel environment Ship emissions