检索结果-南通市图书馆

Structural and electronic properties of atomic oxygen adsorption on Cu(111) surface:A first-principles investigation

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2013年第3期56卷 573-580页

作者： ma liangcai ZHANG JianMin XU KeWei College of Physics and Information Technology Shaanxi Normal University School of Physics and Electrical Information Engineering Ningxia University State Key Laboratory for Mechanical Behavior of materials Xi'an Jiaotong University

By using the first-principles calculations,we have systematically investigated the adsorption of atomic oxygen on Cu(111) surface for a wide range of coverages Θ(from 0.11 to 1.00 ML) and adsorption sites.We found that the fcc-hollow site is the most stable site for oxygen adsorption.The adsorption energy decreases with increasing oxygen coverage due to the increasing repulsive interaction in the overlayer O adatoms.Except for coverage of 1.00 ML,the oxygen-induced lateral relaxations and bucklings are found in the outermost three Cu layers,and the hillock-like as well as ridge-like bucklings are also found for Θ=0.25 ML and Θ=0.75 ML as well as Θ=0.50 ML,respectively.With an increasing oxygen coverage,the work function increases and the surface dipole moment decreases.Electron transfer from the first layer Cu atoms to O adatoms indicates the O-Cu bond having some degree of ionic character,while the hybridization between O 2p and Cu 3d orbitals implies that it also has some degree of covalence character.Moreover,with the increasing oxygen coverage,more Cu 3d and O 2p states are empty thus weakening the binding of O/Cu(111) system,but increase in the PDOS at the Fermi level.This implies an enhancement in the metallic character of the O/Cu(111) system.

关键词： adsorption oxygen relaxation electronic structures first-principles calculation

First-principles study of the adsorption of oxygen atoms on copper nanowires

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2012年第3期55卷 413-418页

作者： ma liangcai ZHANG JianMin XU KeWei College of Physics and Information Technology Shaanxi Normal UniversityXi’an 710062China School of Physics and Electrical Information Engineering Ningxia UniversityYinchuan 750021China Department of Physics Xi’an University of Arts and ScienceXi’an 710065China

By using first-principles calculations,we have systematically investigated the structural stability and electronic properties of a single oxygen atom adsorbed on the surface of foursquare Cu nanowires for a wide range of adsorption sites.In view of binding energy maximization,we found that the long bridge site at the edge of the Cu nanowires is the most stable site for oxygen adsorption,which is always slightly energetically favorable compared with the hollow site at the surface.The electron transferring from Cu atoms to O adatom and a significant polarization indicate the O-Cu chemical bond,showing some degree of ionic character.In addition,the hybridization between O-2p and Cu-3d states implies the O-Cu bond which also shows some degree of covalence character.The main factors which affect the oxygen preferred adsorption site are analyzed from the local geometrical configurations and electronic properties.

关键词：第一原理计算原子吸附铜原子纳米线氧原子结构稳定性电子性质吸附原子

Structural and electronic properties of atomic oxygen adsorption on Cu(111) surface:A first-principles investigation

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2013年第3期56卷 573-580页

关键词： Cu(111) 第一原理计算吸附结构氧原子电子性质表面 3d轨道覆盖层

Single-shot lensless imaging with fresnel zone aperture and incoherent illumination

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Light(Science & Applications) 2020年第1期9卷 1509-1519页

作者： Jiachen Wu Hua Zhang Wenhui Zhang Guofan Jin liangcai Cao George Barbastathis State Key Laboratory of Precision Measurement Technology and Instruments Department of Precision InstrumentsTsinghua University100084 BeijingChina Department of Mechanical Engineering Massachusetts Institute of Technology77 Massachusetts AvenueCambridgeMA 02139USA

Lensless imaging eliminates the need for geometric isomorphism between a scene and an image while allowing the construction of compact,lightweight imaging systems.However,a challenging inverse problem remains due to the low reconstructed signal-to-noise ratio.Current implementations require multiple masks or multiple shots to denoise the reconstruction.We propose single-shot lensless imaging with a Fresnel zone aperture and incoherent illumination.By using the Fresnel zone aperture to encode the incoherent rays in wavefront-like form,the captured pattern has the same form as the inline hologram.Since conventional backpropagation reconstruction is troubled by the twin-image problem,we show that the compressive sensing algorithm is effective in removing this twin-image artifact due to the sparsity in natural scenes.The reconstruction with a significantly improved signal-to-noise ratio from a single-shot image promotes a camera architecture that is flat and reliable in its structure and free of the need for strict calibration.

关键词： illumination Fresnel removing

Li原子和Ca原子修饰VO_(2)单层储氢性能的第一性原理研究

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

人工晶体学报 2023年第11期52卷 2014-2023页

作者：侯茵茵马良财宁夏大学物理学院银川750021

具有高储氢容量和可逆储氢性能的新材料的开发对氢能的大规模利用至关重要。基于第一性原理计算,研究了Li原子和Ca原子单独修饰和共修饰VO_(2)单层体系的H 2分子存储性能。结果表明Li原子和Ca原子均能稳定结合在VO_(2)单层表面而不产生... 详细信息

具有高储氢容量和可逆储氢性能的新材料的开发对氢能的大规模利用至关重要。基于第一性原理计算,研究了Li原子和Ca原子单独修饰和共修饰VO_(2)单层体系的H 2分子存储性能。结果表明Li原子和Ca原子均能稳定结合在VO_(2)单层表面而不产生金属团簇。单个Li原子和Ca原子分别最多可稳定吸附3个和6个H 2分子,且H 2分子平均吸附能均大于0.20 eV/H 2。吸附体系差分电荷和态密度分析结果表明,氢分子的极化机制以及氢分子与金属原子间的轨道杂化作用是H 2分子在金属原子周围稳定吸附的主要原因。Li原子修饰体系的储氢质量密度随着Li原子覆盖度的增加而逐渐增加,而Ca原子修饰体系的储氢质量密度在低金属覆盖度时较高;Li/Ca共修饰体系的储氢质量密度有所增加,其储氢质量密度为5.00%(质量分数)。此外,考虑了不同温度和压强条件下储氢体系的稳定性。

关键词： VO_(2)单层储氢第一性原理计算锂原子钙原子修饰

Fe或Cr单原子链填充Cu纳米管的稳定性与磁性

在线全文

学校读者我要写书评

暂无评论

复合材料学报 2017年第11期34卷 2509-2515页

作者：马良财马玲张建民宁夏大学物理与电子电气工程学院银川750021 陕西师范大学物理学与信息技术学院西安710119

基于密度泛函理论框架下的第一性原理计算,系统地研究了过渡金属(TM)Fe或Cr线性单原子链填充(6,6)Cu纳米管(Fe@CuNT或Cr@CuNT)所形成复合结构的稳定性、磁性和电子特性。相对于孤立单原子链的单原子平均结合能,Fe@CuNT和Cr@CuNT复合结... 详细信息

基于密度泛函理论框架下的第一性原理计算,系统地研究了过渡金属(TM)Fe或Cr线性单原子链填充(6,6)Cu纳米管(Fe@CuNT或Cr@CuNT)所形成复合结构的稳定性、磁性和电子特性。相对于孤立单原子链的单原子平均结合能,Fe@CuNT和Cr@CuNT复合结构的平均结合能大大增加,表明Cu纳米管的包裹使Fe或Cr单原子链的稳定性显著增强。外部Cu原子与内部TM原子间的化学键表现出非局域金属键特性,Fe@CuNT和Cr@CuNT复合结构的磁基态分别为为铁磁态和反铁磁态。对Fe@CuNT和Cr@CuNT复合结构内部Fe原子和Cr原子的自旋磁矩和轨道磁矩进行了计算。相对于自由单原子链,Fe@CuNT和Cr@CuNT复合结构的磁晶各向异性能显著增强,因此Fe@CuNT和Cr@CuNT复合结构可应用于超高密度磁存储中。Cu纳米管的包裹使Fe@CuNT复合结构的易磁化方向相对于自由Fe单原子链的易磁化方向发生了改变。此外,Fe@CuNT复合结构在费米能级处较高的自旋极化率使其可应用于自旋电子器件中。

关键词：过渡金属单原子链 Cu纳米管磁性电子结构第一性原理

Prognostic for fuel cell based on particle filter and recurrent neural network fusion structure

在线全文

学校读者我要写书评

暂无评论

能源与人工智能(英文)

能源与人工智能(英文) 2020年第2期2卷 4-14页

作者： Renyou Xie Rui ma Sicheng Pu liangcai Xu Dongdong Zhao Yigeng Huangfu School of Automation Northwestern Polytechnical UniversityXi’an 710072China School of Information Technology and management University of International Business and EconomicsBeijing 100029China

Fuel cells are considered as one of the most promising candidates for future power source due to its high energy density and environmentally friendly properties,whereas the short lifespan blocks its large-scale commercializa-tion.In order to enhance the reliability and durability of proton exchange membrane fuel cell,a fusion prog-nostic approach based on particle filter(model-based)and long-short term memory recurrent neural network(data-driven)is proposed in this paper.Both the remaining useful life estimation and the short-term degradation prediction can be achieved based on the prognostic method.For remaining useful life estimation,the particle filter method is used to identify the model parameters in the training phase and the long-short term memory recurrent neural network is used to update the parameters in the prediction phase.As for short-term degradation prediction,the particle filter and long-short term memory recurrent neural network are firstly trained individually in the training phase and then be fused to make predictions in the prediction phase.The proposed fusion structure is validated by the fuel cell experimental tests data,and results indicate that better prognostic performance can be obtained compared with the individual model-based or data-driven method.

关键词： Fuel cell Prognostic Remaining useful life Degradation prediction machine learning

单晶硅纳米切削过程中微沟槽结构金刚石刀具切削性能的分子动力学模拟

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

武汉科技大学学报 2023年第1期46卷 47-52页

作者：马世泽付婷曾良才刘正阳武汉科技大学机械自动化学院湖北武汉430081

基于分子动力学,利用LAMMPS和OVITO软件对单晶硅纳米切削过程进行模拟,研究了V形微沟槽结构对金刚石刀具切削性能的影响。结果表明,在金刚石刀具后刀面构建一定深度的V形微沟槽能够减少工件亚表面损伤,同时也对工件加工质量及刀具抗磨... 详细信息

基于分子动力学,利用LAMMPS和OVITO软件对单晶硅纳米切削过程进行模拟,研究了V形微沟槽结构对金刚石刀具切削性能的影响。结果表明,在金刚石刀具后刀面构建一定深度的V形微沟槽能够减少工件亚表面损伤,同时也对工件加工质量及刀具抗磨损性能产生了明显影响,当微沟槽深度为0.75 nm时,金刚石刀具切削性能最佳。

关键词：单晶硅纳米切削微沟槽结构金刚石刀具切削性能分子动力学模拟

在线全文

学校读者我要写书评

暂无评论

炭化工艺对脱水沼渣炭理化性质的影响

化工进展 2019年第3期38卷 1545-1551页

作者：王亮才马欢欢周建斌南京林业大学材料科学与工程学院江苏南京210037

以一级脱水沼渣为原料,通过热重-红外联用分析其失重行为及热解气相产物的组成,采用单因素试验方法,考察炭化温度、升温速率、保温时间对沼渣炭的得率、理化性质的影响。结果表明:360～480℃区域为热解的主要阶段。随着温度的升高,炭得... 详细信息

以一级脱水沼渣为原料,通过热重-红外联用分析其失重行为及热解气相产物的组成,采用单因素试验方法,考察炭化温度、升温速率、保温时间对沼渣炭的得率、理化性质的影响。结果表明:360～480℃区域为热解的主要阶段。随着温度的升高,炭得率、挥发分含量降低,灰分含量增加,固定碳含量在700℃最高(18.37%);随着升温速率提高,灰分、固定碳含量提高,炭得率及挥发分含量降低;随着保温时间的延长,炭得率逐渐降低,对灰分、挥发分、固定碳影响不显著;原料及炭热值较低;重金属Cd和Pb含量低于"有机-无机复混肥料"标准限值(GB 18877—2009);Hg和Cr含量较低,符合肥料用有害重金属元素限值标准,而有益于植物生长的元素Mn和Zn含量较高,本研究为减量化处理复杂沼渣提供了理论依据。

关键词：脱水沼渣热解炭化工艺得炭率重金属