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Two-dimensional semiconductor heterostructures for photocatalytic CO_(2.conversion

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Science China Chemistry 2024年第8期67卷 2434-2447页

作者： Yang Wu Mingyu Wu Yongfu Sun Yi xie Hefei National Research Center for Physical Sciences at Microscale University of Science and Technology of ChinaHefei 230026China

The CO_(2.reduction into carbon-contained fuel via solar energy offers the powerful tools to realize the zero-emission carbon *** to the intriguing features of the two-dimensional(2.)heterostructures,it is susceptible to modulate the electronic structure as well as the surface geometry for optimizing the photocatalytic CO_(2.*** this perspective,we surveyed the fundamental insights of 2. semiconductor heterostructures,involving the fabrication strategies and classification of the 2. semiconductor ***,we have detailly discussed the overview of 2. semiconductor heterostructure for optimizing CO_(2.photocatalytic influenced factors,including the solar energy utilization,photogenerated carriers separation,and redox reaction ***,we showed the significant advantages of 2. heterostructures in elevating CO_(2.photoreduction performance,focusing on activity,selectivity and *** analyzing the limitations and developments,we ended by putting forward insights into the further researches about the CO_(2.photocatalysts and reactor design,even industrial applications.

关键词： two-dimensional semiconductor heterostructures photocatalysis CO_(2.conversion

Local Hamilton type Gradient Estimates and Harnack Inequalities for Nonlinear Parabolic Equations on Riemannian Manifolds

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Acta Mathematicae Applicatae Sinica 2024年第2期40卷 539-546页

作者： Wen WANG Da-peng xie Hui ZHOU School of Mathematics and Statistics Hefei Normal UniversityHefei 230601China

In this paper,we prove a local Hamilton type gradient estimate for positive solution of the nonlinear parabolic equation ut(x,t)=Δu(x,t)+au(x,t) ln u(x,t)+bu^(α)(x,t),on M×(-∞,∞) with α∈R,where a and b are *** ... 详细信息

关键词： nonlinear parabolic equation gradient estimate Harnack inequality

Vibration response and safety control for blasting vibration of the existing tunnel with defects

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Underground Space 2024年第2期15卷 76-89页

作者： Junying Xia Bo Wang Xinxin Guo Zhuoxiong xie Key Laboratory of Transportation Tunnel Engineering Ministry of EducationSouthwest Jiaotong UniversityChengdu 610031China College of Environment and Civil Engineering Chengdu University of TechnologyChengdu 610059China Guangdong Communication Planning&Design Institute Group Co. LtdGuangzhou 510507China

Current studies on blasting construction of small clear-distance tunnels have not considered the impact of existing tunnel lining defects when establishing safety *** paper offers a series of study results based on the blasting project of a new tunnel adjacent to the existing defect Xinling tunnel to thoroughly examine the dynamic response,safety control standards,and measures of the existing defect ***,structural models were developed to investigate the influence of the presence or absence of specific defects(like lining cracks and cavities behind the lining)on the dynamic response of the current tunnel lining to identify the most unfavorable defect ***,establish safety control standards for intact linings and those with the most unfavorable ***,two types of control measures,single safe charge and reasonable delay time,were studied based on the established safety control *** particular,the most adverse position of cracks was the wall facing the explosion,the rise in depth was more unfavorable for vibration response,and the impact of the longitudinal crack was restricted to the vicinity of the *** the vault was the most adverse cavity position,the rise in cavity area was more damaging,and the influence range varied with longitudinal cavity ***,the impact of cracks was mainly evident in the amplification effect of stress at the crack *** contrast,cavities had varied degrees of amplification effects on the vibration velocity and stress response and a relatively extensive influence *** control research was conducted,when the tunnel was intact,with a right wall crack,a vault cavity,and both vault cavity and crack for this project,the peak particle velocity(PPV)of the safety control standard for vibration velocity was 13,10,13,and 8 cm/s,respectively,and the respective single safe charge could be adjusted at 64,53,37,and 2. ***,the presence of different defects had a relati

关键词： Existing tunnel Defect Blasting construction Vibration response Control standards and measures

Stability and performance analysis of the compressed Kalman filter algorithm for sparse stochastic systems

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Science China(Technological Sciences) 2024年第2期67卷 380-394页

作者： LI RongJiang GAN Die xie SiYu LüJinHu Key Laboratory of Systems and Control Academy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing 100190China School of Mathematical Sciences University of Chinese Academy of SciencesBeijing 100049China Zhongguancun Laboratory Beijing 100049China School of Aeronautics and Astronautics University of Electronic Science and Technology of ChinaChengdu 611731China School of Automation Science and Electrical Engineering Beihang UniversityBeijing 100191China

This paper considers the problem of estimating unknown sparse time-varying signals for stochastic dynamic *** deal with the challenges of extensive sparsity,we resort to the compressed sensing method and propose a compressed Kalman filter(KF)*** algorithm first compresses the original high-dimensional sparse regression vector via the sensing matrix and then obtains a KF estimate in the compressed low-dimensional ***,the original high-dimensional sparse signals can be well recovered by a reconstruction *** ensure stability and establish upper bounds on the estimation errors,we introduce a compressed excitation condition without imposing independence or stationarity on the system signal,and therefore suitable for feedback *** further present the performance of the compressed KF ***,we show that the mean square compressed tracking error matrix can be approximately calculated by a linear deterministic difference matrix equation,which can be readily evaluated,analyzed,and ***,a numerical example demonstrates that our algorithm outperforms the standard uncompressed KF algorithm and other compressed algorithms for estimating high-dimensional sparse signals.

关键词： sparse signal compressed sensing Kalman filter algorithm compressed excitation condition stochastic stability tracking performance

Interplay of laser power and pore characteristics in selective laser melting of ZK60 magnesium alloys:A study based on in-situ monitoring and image analysis

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Journal of Magnesium and Alloys 2024年第4期12卷 1346-1366页

作者： Weijie xie Hau-Chung Man Chi-Wai Chan Department of Industrial and Systems Engineering The Hong Kong Polytechnic UniversityHong KongChina School of Mechanical and Aerospace Engineering Queen’s UniversityBelfast BT95AHUK Research Institute for Advanced Manufacturing The Hong Kong Polytechnic UniversityHong KongChina

This study offers significant insights into the multi-physics phenomena of the SLM process and the subsequent porosity characteristics of ZK60 Magnesium(Mg)***-speed in-situ monitoring was employed to visualise process signals in real-time,elucidating the dynamics of melt pools and vapour plumes under varying laser power conditions specifically between 40 W and 60 *** morphological analysis was performed using Scanning-Electron Microscopy(SEM),demonstrating a critical correlation between laser power and pore *** laser power led to increased pore coverage,whereas a denser structure was observed at higher laser *** laser power influence on porosity was further confirmed via Optical Microscopy(OM)conducted on both top and cross-sectional surfaces of the *** increase in laser power resulted in a decrease in pore coverage and pore size,potentially leading to a denser printed part of Mg alloy.X-ray Computed Tomography(XCT)augmented these findings by providing a 3D volumetric representation of the sample internal structure,revealing an inverse relationship between laser power and overall pore *** laser power appeared to favour the formation of interconnected pores,while a reduction in interconnected pores and an increase in isolated pores were observed at higher *** interplay between melt pool size,vapour plume effects,and laser power was found to significantly influence the resulting porosity,indicating a need for effective management of these factors to optimise the SLM process of Mg alloys.

关键词： Selective laser melting(SLM) Magnesium(Mg)alloys Biodegradable implants Porosity In-situ monitoring

A novel multi-slice electromagnetic field-circuit coupling method for transient computation of long-distance gas-insulated transmission lines

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High Voltage 2024年第4期9卷 826-838页

作者： Shucan Cheng Yanpu Zhao Kejia xie Bin Hu School of Electrical Engineering and Automation Wuhan UniversityWuhanChina Shandong Taikai High Voltage Switchgear Co. Ltd.TaianChina

Accurate calculation of short-circuit electromagnetic force is crucial for both mechanical strength check and the optimal design of gas-insulated transmission lines(GIL).Since the full 3D numerical simulation method is highly time-consuming,a novel lightweight 2. multi-slice electromagnetic field-circuit coupled method for computing transient electromagnetic force is proposed,where appropriate port voltage degrees of freedom(DoFs)are introduced for the solid GIL conductor *** the transient magnetic field equations are combined with the constraint equations of circuit part,including nodal voltage and loop current DoFs,a direct field-circuit coupling scheme is thus *** proposed method can simultaneously consider the effect of interphaseshunts and ground wires,as well as the skin effect and proximity *** can accurately capture the transient electromagnetic characteristics of GIL spanning from several to tens of kilometers under different short-circuit *** transient electromagnetic forces,as well as the induced voltages and currents of the enclosure,are analysed by the proposed method for both single-phase and three-phase enclosed GIL under various short-circuit *** proposed method has the advantages of high accuracy and lightweight computational cost,and thus it is also suitable for conducting important simulation tasks such as mechanical strength checks during the design optimisation phase of long-distance GIL.

关键词： transient coupling field

Synthesis and modification of nanowires anchored on electrodes for electrochemical and electrophysical applications

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Nano Research 2024年第10期17卷 8863-8884页

作者： Feiyang Mo Zhitao Chen Nian Liu Xing xie School of Civil and Environmental Engineering Georgia Institute of Technology311 Ferst Drive NWAtlantaGA 30332USA School of Chemical and Biomolecular Engineering Georgia Institute of Technology311 Ferst Drive NWAtlantaGA 30332USA

The integration of nanowires onto electrode surfaces marks a significant advancement over traditional electrode materials,conferring upon nanowire-modified electrodes a vast array of applications within electrochemical and electrophysical *** nanowires used for electrode modification can be catalogized into two distinct types:anchored nanowires and free-standing nanowires.A critical advantage of anchored nanowires lies in their enhanced electrical connectivity with the substrate,which reduces electrode resistance and facilitates charge ***,the anchorage of nanowires onto electrodes provides additional mechanical support,bolstering the structural stability of the nanowire ***,we review the development of anchored nanowires designed for applications in energy storage,electrocatalysis,and electric field treatment(EFT)over the past *** focus on the synthesis and modification strategies employed for anchored nanowires,culminating in the evaluation of these fabrication and enhancement *** this analysis,we aim to furnish comprehensive insights into the preparation of anchored nanowires,guiding the selection of appropriate fabrication processes and subsequent functional modifications.

关键词： electrode modification direct growth etching energy storage electrocatalysis electric field treatment

The reaction mechanism and interfacial crystallization of Al nanoparticle-embedded Ni under shock loading

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Defence Technology（防务技术） 2024年第3期33卷 114-124页

作者： Yifan xie Jian-Li Shao Rui Liu Pengwan Chen State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing100081China Explosion Protection and Emergency Disposal Technology Engineering Research Center of the Ministry of Education Beijing100039China

The shock-induced reaction mechanism and characteristics of Ni/Al system,considering an Al nanoparticle-embedded Ni single crystal,are investigated through molecular dynamics *** the shock melting of Al nanoparticle,interfacial crystallization and dissolution are the main *** reaction degree of Al particle first increases linearly and then logarithmically with time driven by rapid mechanical mixing and following *** reaction rate increases with the decrease of particle diameter,however,the reaction is seriously hindered by interfacial crystallization when the diameter is lower than 9 nm in our ***,we found a negative exponential growth in the fraction of crystallized Al atoms,and the crystallinity of B2.NiAl(up to 2.%)is positively correlated with the specific surface area of Al *** can be attributed to the formation mechanism of B2.NiAl by structural evolution of finite mixing layer near the collapsed *** shock melting of both Al particle and Ni matrix,the liquid-liquid phase inter-diffusion is the main reaction mechanism that can be enhanced by the formation of internal *** addition,the enhanced diffusion is manifested in the logarithmic growth law of mean square displacement,which results in an almost constant reaction rate similar to the mechanical mixing process.

关键词： Shock-induced reaction Molecular dynamics simulations Interfacial crystallization Reaction mechanism

Experimental and numerical flutter analysis of a folding fin with multiple asymmetric free-plays

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Chinese Journal of Aeronautics 2024年第5期37卷 332-348页

作者： Chenyu LIU Chao AN Changchuan xie Xin ZHANG Lan YANG School of Aeronautic Science and Engineering Beihang UniversityBeijing 100191China Beijing Institute of Electronic System Engineering Beijing 100854China Beijing Institute of Astronautical Systems Engineering Beijing 100076China

Experimental folding fin models with an adjustable free-play are tested in a wind *** fin structure is modeled using the free-interface component mode synthesis method,and its free-play is modeled as four independent nonlinear springs with asymmetric stiffness.A nonplanar unsteady vortex-lattice method considering compressibility is employed to address nonlinear deformation and high subsonic *** spline interpolation is improved through projection and *** aeroelastic characteristics of folding fins with different free-play magnitudes,initial conditions and elastic-axis positions are analyzed using an established time-marching method because of its relatively small computation scale and high *** results show good consistency among the presented method,the wind tunnel test and the harmonic balance *** is a negative correlation between the critical speed of divergent motion and the ratio of the initial condition to the free-play *** either the free-play magnitude or the initial condition is extreme(tiny or vast),the system nonlinearity degenerates to ***,the flutter prevention design of a linear model can be applied to a nonlinear model,such as moving the elastic-axis position *** presented fin configuration exhibits an unstable limit cycle oscillation because the orders of coupled flutter modes do not change with variations in equivalent linear stiffness.

关键词： Free-play Limit cycle oscillation Flutter Component mode synthesis Vortex-lattice method