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Epitaxial growth of borophene on graphene surface towards efficient and broadband photodetector

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Nano Research 2024年第4期17卷 3053-3060页

作者： Zenghui Wu Chen Shifan Zitong Wu Yi Liu Wei Shao Xinchao Liang Chuang Hou Guoan Tai The State key laboratory of Mechanics and control of Mechanical structures and laboratory of Intelligent Nano Materials and Devices of Ministry of Education College of Aerospace EngineeringNanjing University of Aeronautics and AstronauticsNanjing 210016China

In-situ integration of multiple materials with well-defined interfaces as heterostructures is of great interest due to their unique properties and potential for new device functionality.Because of its polymorphism and diverse bonding geometries,borophene is a promising candidate for two-dimensional heterostructures,but suitable synthesis conditions have limited its potential applications.Toward this end,we demonstrate the vertical borophene and graphene heterostructures which form by epitaxial growth of borophene onto multilayer graphene on Cu substrates via chemical vapor deposition,where hydrogen and NaBH_(4) are respectively used as the carrier gas and the boron source.The lattice structure of the as-synthesized borophene well coincides with the predictedα′-boron sheet.The borophene-based photodetector shows an excellent broadband photoresponse from the ultraviolet(255 nm)to the infrared(940 nm)wavelengths,with enhanced responsivity compared to pristine borophene or graphene photodetectors.This work informs emerging efforts to integrate borophene into nanoelectronic applications for both fundamental investigations and technological applications.

关键词： borophene graphene heterostructure photodetector two-dimensional materials

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 approaches.The 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 bandgap.The metastructure can also effectively attenuate seismic responses.Compared 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

Adaptive fault-tolerant control for non-minimum phase hypersonic vehicles based on adaptive dynamic programming

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Chinese Journal of Aeronautics 2024年第3期37卷 290-311页

作者： Le WANG Ruiyun QI Bin JIANG State key laboratory of Mechanics and control for Aerospace structures Nanjing University of Aeronautics and AstronauticsNanjing 210016China College of Automation engineering Nanjing University of Aeronautics and AstronauticsNanjing 211106China

In this paper,a novel adaptive Fault-Tolerant control(FTC)strategy is proposed for non-minimum phase Hypersonic Vehicles(HSVs)that are affected by actuator faults and parameter uncertainties.The strategy is based on the output redefinition method and Adaptive Dynamic Programming(ADP).The intelligent FTC scheme consists of two main parts:a basic fault-tolerant and stable controller and an ADP-based supplementary controller.In the basic FTC part,an output redefinition approach is designed to make zero-dynamics stable with respect to the new output.Then,Ideal Internal Dynamic(IID)is obtained using an optimal bounded inversion approach,and a tracking controller is designed for the new output to realize output tracking of the nonminimum phase HSV system.For the ADP-based compensation control part,an ActionDependent Heuristic Dynamic Programming(ADHDP)adopting an actor-critic learning structure is utilized to further optimize the tracking performance of the HSV control system.Finally,simulation results are provided to verify the effectiveness and efficiency of the proposed FTC algorithm.

关键词： Hypersonic vehicle Fault-tolerant control Non-minimum phase system Adaptive control Nonlinear control Adaptive dynamic programming

Isogeometric Analysis for the Arbitrary AFG Microbeam with Two-Phase Nonlocal Stress-Driven Model

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Acta Mechanica Solida Sinica 2024年第2期37卷 341-360页

作者： Pei-Liang Bian Zhaowei Liu Hai Qing Tiantang Yu Department of engineering Mechanics Hohai UniversityNanjing211100China State key laboratory of Mechanics and control of Mechanical structures Nanjing University of Aeronautics and AstronauticsNanjing210016China

Scale effects play critical roles in the mechanical responses of microstructures.An isogeometric analysis was developed here to investigate the mechanical responses of an axially functionally graded microbeam.The Euler–Bernoulli beam model was utilized,and size effects in the structure were modeled with a stress-driven two-phase local/nonlocal integral constitution.The governing equation of microstructures was given in an equivalent differential form with two additional constitutive boundary conditions.The framework was verified and utilized to analyze the microbeam’s static and dynamic mechanical responses.The present work showed great potential for modeling various types of functionally graded microstructures.

关键词： Isogeometric analysis Size effect Functionally graded material Nonlocal theory Euler-Bernoulli beam

Web Layout Design of Large Cavity structures Based on Topology Optimization

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Computer Modeling in engineering & Sciences 2024年第3期138卷 2665-2689页

作者： Xiaoqiao Yang Jialiang Sun Dongping Jin State key laboratory ofMechanics and control for Aerospace structures College of Aerospace EngineeringNanjing University of Aeronautics and AstronauticsNanjing210016China

Large cavity structures are widely employed in aerospace engineering, such as thin-walled cylinders, blades andwings. Enhancing performance of aerial vehicles while reducing manufacturing costs and fuel consumptionhas become a focal point for contemporary researchers. Therefore, this paper aims to investigate the topologyoptimization of large cavity structures as a means to enhance their performance, safety, and efficiency. By usingthe variable density method, lightweight design is achieved without compromising structural strength. Theoptimization model considers both concentrated and distributed loads, and utilizes techniques like sensitivityfiltering and projection to obtain a robust optimized configuration. The mechanical properties are checked bycomparing the stress distribution and displacement of the unoptimized and optimized structures under the sameload. The results confirm that the optimized structures exhibit improved mechanical properties, thus offering keyinsights for engineering lightweight, high-strength large cavity structures.

关键词： Topology optimization lightweight design web layout design cavity structure

Effect of CeO_(2) nanoparticle sizes on catalytic performances of sulfated CeO_(2)/Al_(2)O_(3) catalyst in NH_(3)-SCR reaction

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Journal of Rare Earths 2024年第3期42卷 515-522,I0004页

作者： Zhenghua Hu Dongqi An Lei Zhang Xuping Wang Siyong Fang Xinyun Tian Liu Qiu Jingfang Sun Tingzhen Li Lin Dong School of Environmental and Chemical engineering Chongqing Three Gorges UniversityChongqing404000China key laboratory of Water Environment evolution and Pollution control in the Three Gorges Reservoir Chongqing Three Gorges UniversityChongqing404000China Jiangsu key laboratory of Vehicle Emissions control Center of Modern AnalysisNanjing UniversityNanjing210093China

The sulfated CeO_(2)/Al_(2)O_(3) catalysts with different sizes of CeO_(2)nanoparticles were prepared by using pure H_2O or acetic acid solution as impregnation solvent, and the influence of sizes of CeO_(2) nanoparticles on the catalytic performances of the sulfated CeO_(2)/Al_(2)O_(3) catalyst was studied. The catalytic performance tests show that the sulfated CeO_(2)/Al_(2)O_(3) catalyst using acetic acid solution as impregnation solvent has better catalytic activity and the resistance to K+poisoning than the sulfated CeO_(2)/Al_(2)O_(3) catalyst using pure H_(2)O as impregnation solvent. The excellent catalytic performances can be ascribed to the smaller sizes of CeO_(2) nanoparticles in CeO_(2)/Al_(2)O_(3) catalyst using acetic acid solution, which results in larger amount of adsorbed sulfate species, surface acid sites, surface active oxygen species and excellent redox property. These features are helpful for improving the catalytic performances of sulfated CeO_(2)/Al_(2)O_(3) catalyst using smaller amount of CeO_(2) to cut the costs.

关键词： Cerium-based catalyst Nanoscale effect NH_(3)selective catalytic reaction Sulfation process Alkali metal poisoning Rare earths

Chemical characteristics of long-term acid rain and its impact on lake water chemistry:A case study in Southwest China

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Journal of Environmental Sciences 2024年第4期138卷 121-131页

作者： Liuyi Zhang JiaWang Shuxiao Wang Chunbo Wang Fumo Yang Tingzhen Li Chongqing key laboratory of Water Environment evolution and Pollution control in Three Gorges Reservoir Chongqing Three Gorges UniversityWanzhou 404000China State key Joint laboratory of Environment Simulation and Pollution control School of EnvironmentTsinghua UniversityBeijing 100084China College of Carbon Neutrality Future Technology Sichuan UniversityChengdu 610065China National engineering Research Center on Flue Gas Desulfurization Chengdu 610065China

The chemical composition of acid rain and its impact on lake water chemistry in Chongqing,China,from 2000 to 2020 were studied in this study.The regional acid rain intensity is affected jointly by the acid gas emissions and the neutralization of alkaline substances.The pH of precipitation experienced three stages of fluctuating decline,continuous improvement,and a slight correction.Precipitation pH showed inflection points in 2010,mainly due to the total control actions of SO_(2)and NO_(x)implemented in 2011.The total ion concentrations in rural areas and urban areas were 489.08μeq/L and 618.57μeq/L,respectively.The top four ions were SO_(4)^(2-),Ca^(2+),NH_(4)^(+)and NO_(3)^(-),which accounted for more than 90%of the total ion concentration,indicating the anthropogenic effects.Before 2010,SO_(4)^(2-)fluctuated greatly while NO_(3)^(-)continued to rise;however,after 2010,both SO_(4)^(2-)and NO_(3)^(-)began to decline rapidly,with the rates of-12.03μeq/(L·year)and-4.11μeq/(L·year).Because the decline rate of SO_(4)^(2-)was 2.91 times that of NO_(3)^(-),the regional acid rain has changed from sulfuric acid rain to mixed sulfuric and nitric acid rain.The lake water is weakly acidic,with an average pH of 5.86,and the acidification frequency is 30.00%.Acidification of lake water is jointly affected by acid deposition and acid neutralization capacity of lake water.Acid deposition has a profound impact on water acidification,and nitrogen(N)deposition,especially reduced N deposition,should be the focus of future research.

关键词： Acid rain Chemical composition Neutralization Nitrogen deposition Water acidification

Phase-Field Simulation of Sintering Process:A Review

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Computer Modeling in engineering & Sciences 2024年第8期140卷 1165-1204页

作者： Ming Xue Min Yi State key laboratory ofMechanics and control forAerospace structures&Institute for Frontier Science&key laboratory for Intelligent Nano Materials and Devices of Ministry of Education&College of Aerospace engineering Nanjing University of Aeronautics and Astronautics(NUAA)Nanjing210016China

Sintering,a well-established technique in powder metallurgy,plays a critical role in the processing of high melting point materials.A comprehensive understanding of structural changes during the sintering process is essential for effective product assessment.The phase-field method stands out for its unique ability to simulate these structural transformations.Despite its widespread application,there is a notable absence of literature reviews focused on its usage in sintering simulations.Therefore,this paper addresses this gap by reviewing the latest advancements in phase-field sintering models,covering approaches based on energy,grand potential,and entropy increase.The characteristics of various models are extensively discussed,with a specific emphasis on energy-based models incorporating considerations such as interface energy anisotropy,tensor-form diffusion mechanisms,and various forms of rigid particle motion during sintering.Furthermore,the paper offers a concise summary of phase-field sintering models that integrate with other physical fields,including stress/strain fields,viscous flow,temperature field,and external electric fields.In conclusion,the paper provides a succinct overview of the entire content and delineates potential avenues for future research.

关键词： Phase-field model review sintering additive manufacturing

An Aerial–Wall Robotic Insect That Can Land, Climb, and Take Off from Vertical Surfaces

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Research 2024年第1期2023卷 149-163页

作者： Qian Li Haoze Li Huan Shen Yangguang Yu Haoran He Xincheng Feng Yi Sun Zhiyuan Mao Guangming Chen Zongjun Tian Lida Shen Xiangming Zheng Aihong Ji College of Mechanical and Electrical engineering Nanjing University of Aeronautics and AstronauticsNanjingChina College of Aerospace engineering Nanjing University of Aeronautics and AstronauticsNanjingChina State key laboratory of Mechanics and control for Aerospace structures Nanjing University of Aeronautics and AstronauticsNanjingChina

Insects that can perform flapping-wing flight,climb on a wall,and switch smoothly between the 2 locomotion regimes provide us with excellent biomimetic models.However,very few biomimetic robots can perform complex locomotion tasks that combine the 2 abilities of climbing and flying.Here,we describe an aerial–wall amphibious robot that is self-contained for flying and climbing,and that can seamlessly move between the air and wall.It adopts a flapping/rotor hybrid power layout,which realizes not only efficient and controllable flight in the air but also attachment to,and climbing on,the vertical wall through a synergistic combination of the aerodynamic negative pressure adsorption of the rotor power and a climbing mechanism with bionic adhesion performance.On the basis of the attachment mechanism of insect foot pads,the prepared biomimetic adhesive materials of the robot can be applied to various types of wall surfaces to achieve stable climbing.The longitudinal axis layout design of the rotor dynamics and control strategy realize a unique cross-domain movement during the flying–climbing transition,which has important implications in understanding the takeoff and landing of insects.Moreover,it enables the robot to cross the air–wall boundary in 0.4 s(landing),and cross the wall–air boundary in 0.7 s(taking off).The aerial–wall amphibious robot expands the working space of traditional flying and climbing robots,which can pave the way for future robots that can perform autonomous visual monitoring,human search and rescue,and tracking tasks in complex air–wall environments.

关键词： robot smoothly Vertical