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Single-photon-level light storage with distributed Rydberg excitations in cold atoms

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Frontiers of physics 2022年第2期17卷 25-32页

作者： Hanxiao Zhang Jinhui wu M.Artoni G.c.La Rocca center for Quantum Sciences and School of Physics Northeast Normal UniversityChangchun 130024China Department of Engineering and Information Technology and Istituto Nazionale di Ottica(INO-cNR) Brescia University25133 BresciaItaly Scuola Normale Superiore and cNISM 56126 PisaItaly

We present an improved version of the superatom(SA)model to examine the slow-light dynamics of a few-photons signal field in cold Rydberg atoms with van der Waals(vdW)interactions.A main feature of this version is that it promises consistent estimations on total Rydberg excitations based on dynamic equations of SAs or *** consider two specific cases in which the incident signal field contains more photons with a smaller detuning or less photons with a larger detuning so as to realize the single-photon-level light *** is found that vdW interactions play a significant role even for the slow-light dynamics of a single-photon signal field as distributed Rydberg excitations are inevitable in the picture of dark-state ***,the stored(retrieved)signal field exhibits a clearly asymmetric(more symmetric)profile because its leading and trailing edges undergo different(identical)traveling journeys,and higher storage/retrieval efficiencies with well preserved profiles apply only to weaker and well detuned signal *** findings are crucial to understand the nontrivial interplay of single-photon-level light storage and distributed Rydberg excitations.

关键词： few-photons light storage distributed Rydberg excitation cold Rydberg atom improved superatom model

Liquefaction susceptibility and deformation characteristics of saturated coral sandy soils subjected to cyclic loadings-a critical review

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Earthquake Engineering and Engineering Vibration 2024年第1期23卷 261-296页

作者： chen Guoxing Qin You Ma Weijia Liang Ke wu Qi c.Hsein Juang Institute of Geotechnical Engineering Nanjing Tech UniversityNanjing 210009China civil Engineering and Earthquake Disaster Prevention center of Jiangsu Province Nanjing 210009China School of Mechanical Engineering Nanjing University of Science and TechnologyNanjing 210094China college of civil Aviation Nanjing University of Aeronautics and AstronauticsNanjing 210016China Glenn Department of civil Engineering Clemson UniversityClemsonSC 29634USA

coral sandy soils widely exist in coral island reefs and seashores in tropical and subtropical *** to the unique marine depositional environment of coral sandy soils,the engineering characteristics and responses of these soils subjected to monotonic and cyclic loadings have been a subject of intense interest among the geotechnical and earthquake engineering *** paper critically reviews the progress of experimental investigations on the undrained behavior of coral sandy soils under monotonic and cyclic loadings over the last three *** focus of coverage includes the contractive-dilative behavior,the pattern of excess pore-water pressure(EPWP)generation and the liquefaction mechanism and liquefaction resistance,the small-strain shear modulus and strain-dependent shear modulus and damping,the cyclic softening feature,and the anisotropic characteristics of undrained responses of saturated coral sandy *** particular,the advances made in the past decades are reviewed from the following aspects:(1)the characterization of factors that impact the mechanism and patterns of EPWP build-up;(2)the identification of liquefaction triggering in terms of the apparent viscosity and the average flow coefficient;(3)the establishment of the invariable form of strain-based,stress-based,or energy-based EPWP ratio formulas and the unique relationship between the new proxy of liquefaction resistance and the number of cycles required to reach liquefaction;(4)the establishment of the invariable form of the predictive formulas of small strain modulus and strain-dependent shear modulus;and(5)the investigation on the effects of stress-induced anisotropy on liquefaction susceptibility and dynamic deformation *** gained through the critical review of these advances in the past decades offer a perspective for future research to further resolve the fundamental issues concerning the liquefaction mechanism and responses of coral sandy sites subjecte

关键词： liquefaction susceptibility dynamic deformation characteristics coral sandy soil cyclic loading review and prospect

Morphology and orientation evolution of cu_(6)Sn_(5)grains on(001)cu and(011)cu single crystal substrates under temperature gradient

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Journal of Materials Science & Technology 2021年第36期95卷 29-39页

作者： Yuanyuan Qiao Xiaoying Liu Ning Zhao Lawrence c M wu chunying Liu Haitao Ma School of Materials Science and Engineering Dalian University of TechnologyDalian 116024China Department of Materials Science and Engineering City University of Hong KongHong Kong Special Administrative RegionChina

The morphology and orientation evolution of cu_(6)Sn_(5)grains formed on(001)cu and(011)cu single crystal substrates under temperature gradient(TG)were *** initial orientated prism-type cu_(6)Sn_(5)grains transformed to non-orientated scallop-type after isothermal ***,the cu_(6)Sn_(5)grains with strong texture were revealed on cold end single crystal cu substrates by imposing *** cu_(6)Sn_(5)grains on(001)cu grew along their c-axis parallel to the substrate and finally merged into one grain to form a fully IMc joint,while those on(011)cu presented a strong texture and merged into a few dominant cu_(6)Sn_(5)grains showing about 30°angle with the *** merging between neighboring cu_(6)Sn_(5)grain pair was attributed to the rapid grain growth and grain boundary ***,a model was put forward to describe the merging *** different morphology and orientation evolutions of the cu_(6)Sn_(5)grains on single crystal and polycrystal cu substrates were revealed based on crystallographic relationship and cu *** method for controlling the morphology and orientation of cu_(6)Sn_(5)grains is really benefitial to solve the reliability problems caused by anisotropy in 3 D packaging.

关键词： 3D packaging Single crystal cu Temperature gradient Orientation Disregistry Grain boundary migration

Aerodynamic characteristics of a high-speed train crossing the wake of a bridge tower from moving model experiments

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Railway Engineering Science 2022年第2期30卷 221-241页

作者： Jinfeng wu Xiaozhen Li c.S.cai Dejun Liu Department of Bridge Engineering School of Civil EngineeringSouthwest Jiaotong UniversityChengduChina 610031 Department of Bridge Engineering School of TransportationSoutheast UniversityNanjingJiangsuChina Department of civil and Environmental Engineering Louisiana State UniversityBaton RougeLA 70803USA college of civil Engineering and Architecture Jiaxing UniversityJiaxing 314001ZhejiangChina

In a strong crosswind,the wake of a bridge tower will lead to an abrupt change of the aerodynamic forces acting on a vehicle passing through it,which may result in problems related to the transportation *** study investigates the transient aerodynamic characteristics of a high-speed train moving in a truss girder bridge and passing by a bridge tower in a wind *** scaled ratio of the train,bridge,and tower are 1:*** of various parameters such as the incoming wind speed,train speed,and yaw angle on the aerodynamic performance of the train were *** the sudden change mechanism of aerodynamic loads on the train when it crosses over the tower was further *** results show that the bridge tower has an apparent shielding effect on the train passing through it,with the influencing width being larger than the width of the *** train speed is the main factor affecting the influencing width of aerodynamic coefficients,and the mutation amplitude is mainly related to the yaw angle obtained by changing the incoming wind speed or train *** vehicle movement introduces an asymmetry of loading on the train in the process of approaching and leaving the wake of the bridge tower,which should not be neglected.

关键词： Vehicle aerodynamics Wind tunnel test Moving train Bridge tower Shielding effect Sudden change mechanism Truss bridge

Development of Lattice Boltzmann Flux Solver for Simulation of Incompressible Flows

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Advances in Applied Mathematics and Mechanics 2014年第4期6卷 436-460页

作者： c.Shu Y.Wang c.J.Teo J.wu Department of Mechanical Engineering National University of Singapore10 Kent Ridge CrescentSingapore 119260 Department of Aerodynamics College of Aerospace EngineeringNanjing University of Aeronautics and AstronauticsNanjing 210016China

A lattice Boltzmann flux solver(LBFS)is presented in this work for simulation of incompressible viscous and inviscid *** new solver is based on chapman-Enskog expansion analysis,which is the bridge to link Navier-Stokes(N-S)equations and lattice Boltzmann equation(LBE).The macroscopic differential equations are discretized by the finite volume method,where the flux at the cell interface is evaluated by local reconstruction of lattice Boltzmann solution from macroscopic flow variables at cell *** new solver removes the drawbacks of conventional lattice Boltzmann method such as limitation to uniform mesh,tie-up of mesh spacing and time interval,limitation to viscous *** is validated by its application to simulate the viscous decaying vortex flow,the driven cavity flow,the viscous flow past a circular cylinder,and the inviscid flow past a circular *** obtained numerical results compare very well with available data in the literature,which show that LBFS has the second order of accuracy in space,and can be well applied to viscous and inviscid flow problems with non-uniform mesh and curved boundary.

关键词： chapman-Enskog analysis flux solver incompressible flow Navier-Stokes equation lattice Boltzmann equation

Tuning the interfacial reaction environment via pH-dependent and induced ions to understand c–N bonds coupling performance in NO3- integrated cO2 reduction to carbon and nitrogen compounds over dual cu-based N-doped carbon catalyst

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Journal of Energy chemistry 2025年第1期 273-285页

作者： Tianhang Zhou chen Shen Zhenghao wu Xingying Lan Yi Xiao college of carbon Neutrality Future Technology State Key Laboratory of Heavy Oil Processing China University of Petroleum (Beijing) Institute of Materials Science TU Darmstadt Department of chemistry Xi'an Jiaotong-Liverpool University Department of Mechanical and Mechatronics Engineering and Waterloo Institute of Nanotechnology University of Waterloo Waterloo

Dual atomic catalysts （DAc）,particularly copper （cu2）-based nitrogen （N） doped graphene,show great potential to effectively convert cO2and nitrate （NO3-） into important industrial chemicals such as ethylene,glycol,acetamide,and urea through an efficient catalytical process that involves c–c and c–N ***,the origin of the coupling activity remained unclear,which substantially hinders the rational design of cu-based catalysts for the N-integrated cO2reduction reaction （cO2RR）.To address this challenge,this work performed advanced density functional theory calculations incorporating explicit solvation based on a cu2-based N-doped carbon (cu2N6c10) catalyst for *** calculations are aimed to gain insight into the reaction mechanisms for the synthesis of ethylene,acetamide,and urea via coupling in the interfacial reaction *** to the sluggishness of cO2,the formation of a solvation electric layer by anions （F-,cl-,Br-,and I-） and cations (Na+,Mg2+,K+,and ca2+) leads to electron transfer towards the cu *** process significantly accelerates the reduction of *** results reveal that*cO intermediates play a pivotal role in N-integrated ***,the cu2-based N-doped carbon catalyst examined in this study has demonstrated the most potential for c–N coupling to *** findings reveal that through the process of a condensation reaction between*cO and NH2OH for urea synthesis,*NO3-is reduced to*NH3,and*cO2to*ccO at dual cu atom *** dual-site reduction facilitates the synthesis of acetamide through a nucleophilic reaction between NH3and the ketene ***,we found that the I-and Mg2+ions,influenced by pH,were highly effective for acetamide and ammonia synthesis,except when F-and ca2+were ***,the mechanisms of c–N bond formation were investigated via ab-initio molecular dynamics simulations,and we found that adjusting the micro-environment can change the dominant side reaction,shift

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Engineering Design of High Quality GaN Epitaxy on Silicon Substrate Using Varying GaN/AlGaN composite Buffer Structures

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稀有金属材料与工程 2012年第S1期41卷 57-60页

作者： wu, G. M. Tu, K. N. Kuo, c. c. Univ calif Los Angeles Dept Mat Sci & Engn Los Angeles CA 90095 USA chang Gung Univ Inst Electroopt Engn Tao Yuan 333 Taiwan

High quality GaN epitaxy thin films have been desired for the energy-efficient,solid-state semiconductor illuminating *** substrates offer high crystal quality,low wafer cost,large wafer size,and potential integration with the well-established silicon processing ***,due to the large mismatch in lattice constants and thermal expansion coefficients,it is still challenging to grow high quality GaN on silicon *** this study,high quality GaN epitaxy has been engineering designed to grow on Si(111)substrate using varying GaN/AlGaN composite buffer structures by an Axitron 200 metal-organic vapor phase epitaxy deposition system.A thin AlN seed layer of 25 nm was firstly grown at 720℃.AlGaN layer of different thickness was then grown at 1050℃with subsequent GaN thin film until the total thickness reached 500 *** thickness of the subsequent GaN thin film could be increased by reducing the AlGaN thickness in the composite buffer *** results have shown that the lower GaN/AlGaN thickness ratio would decrease the dislocation density and provide crack-free,mirror-like upper GaN crystal thin *** the other hand,the GaN/AlGaN thickness ratio could be designed to be 2-6 to balance the processing cost and the thin film quality for engineering *** dislocation density has been about 2×10 9 *** addition,dislocation close loop was observed near the GaN/AlGaN *** annihilation mechanism could be depicted by the reduction in dislocation strain energy.

关键词： gallium nitride dislocation density silicon substrate buffer layer

In situ DRIFTS study of photocatalytic cO_(2) reduction under UV irradiation

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Frontiers of chemical Science and Engineering 2010年第2期4卷 120-126页

作者： Jeffrey c.S.wu chao-Wei HUANG Department of chemical Engineering Taiwan UniversityTaipei 10617China

Photocatalytic reduction of cO_(2) on TiO_(2) and cu/TiO_(2) photocatalysts was studied by in situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)under UV *** photocatalysts were prepared by sol-gel method via controlled hydrolysis of titanium(IV)*** precursor was loaded onto TiO_(2) during sol-gel procedure.A large amount of adsorbed H_(2)O and surface OH groups was detected at 25℃on the TiO_(2) photocatalyst after being treated at 500℃under air *** and bicarbonate were formed rapidly due to the reaction of cO_(2) with oxygen-vacancy and OH groups,respectively,on TiO_(2) surface upon cO_(2)*** IR spectra indicated that,under UV irradiation,gas-phase cO_(2) further combined with oxygen-vacancy and OH groups to produce more carbonate or *** weak signals of reaction intermediates were found on the IR spectra,which were due to the slow photocatalytic cO_(2) reduction on *** electrons merge with H^(+)ions to form H atoms,which progressively reduce cO_(2) to form formic acid,dioxymethylene,formaldehyde and methoxy as observed in the IR *** well-dispersed cu,acting as the active site significantly increases the amount of formaldehyde and dioxymethylene,thus promotes the photoactivity of cO_(2) reduction on cu/TiO_(2).A possible mechanism of the photocatalytic cO_(2) reduction is proposed based on these intermediates and products on the photocatalysts.

关键词： photocatalysis cO_(2) titania in situ infrared spectroscopy cu/TiO_(2)

Simulation of Incompressible Viscous Flows by Local DFD-Immersed Boundary Method

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Advances in Applied Mathematics and Mechanics 2012年第3期4卷 311-324页

作者： Y.L.wu c.Shu H.Ding Department of Mechanical Engineering National University of Singapore10 Kent Ridge CrescentSingapore 117576 Department of Modern Mechanics University of Science and Technology of ChinaHefeiAnhui 230026China

A local domain-free discretization-immersed boundary method(DFDIBM)is presented in this paper to solve incompressible Navier-Stokes equations in the primitive variable *** the conventional immersed boundary method(IBM),the local DFD-IBM solves the governing equations in the whole domain including exterior and interior of the immersed *** effect of immersed boundary to the surrounding fluids is through the evaluation of velocity at interior and exterior dependent *** be specific,the velocity at interior dependent points is computed by approximate forms of solution and the velocity at exterior dependent points is set to the wall *** compared to the conventional IBM,the present approach accurately implements the non-slip boundary *** a result,there is no flow penetration,which is often appeared in the conventional IBM *** present approach is validated by its application to simulate incompressible viscous flows around a circular *** obtained numerical results agree very well with the data in the literature.

关键词： Local domain free discretization(local DFD) immersed boundary method(IBM) incompressible flow flow past a circular cylinder