期刊文献+
共找到1,034篇文章
< 1 2 52 >
每页显示 20 50 100
Metal-N_(4)model single‐atom catalyst with electroneutral quadri‐pyridine macrocyclic ligand for CO_(2)electroreduction
1
作者 Jian‐Zhao Peng Yin‐Long Li +7 位作者 Yao‐Ti Cheng Fu‐Zhi Li Bo Cao Qing Wang Xian Yue Guo‐Tao Lai Yang‐Gang Wang Jun Gu 《Carbon Energy》 SCIE EI CAS CSCD 2024年第8期122-133,共12页
Metal–N–C single‐atom catalysts,mostly prepared from pyrolysis of metalorganic precursors,are widely used in heterogeneous electrocatalysis.Since metal sites with diverse local structures coexist in this type of ma... Metal–N–C single‐atom catalysts,mostly prepared from pyrolysis of metalorganic precursors,are widely used in heterogeneous electrocatalysis.Since metal sites with diverse local structures coexist in this type of material and it is challenging to characterize the local structure,a reliable structure–property relationship is difficult to establish.Conjugated macrocyclic complexes adsorbed on carbon support are well‐defined models to mimic the singleatom catalysts.Metal–N_(4)site with four electroneutral pyridine‐type ligands embedded in a graphene layer is the most commonly proposed structure of the active site of single‐atom catalysts,but its molecular counterpart has not been reported.In this work,we synthesized the conjugated macrocyclic complexes with a metal center(Co,Fe,or Ni)coordinated with four electroneutral pyridinic ligands as model catalysts for CO_(2)electroreduction.For comparison,the complexes with anionic quadri‐pyridine macrocyclic ligand were also prepared.The Co complex with the electroneutral ligand expressed a turnover frequency of CO formation more than an order of magnitude higher than that of the Co complex with the anionic ligand.Constrained ab initio molecular dynamics simulations based on the well‐defined structures of the model catalysts indicate that the Co complex with the electroneutral ligand possesses a stronger ability to mediate electron transfer from carbon to CO_(2). 展开更多
关键词 ab initio molecular dynamics CO_(2)reduction electrocatalysis model catalyst single‐atom catalyst
下载PDF
Entropy squeezing and atomic inversion in the K-photon Jaynes–Cummings model in the presence of the Stark shift and a Kerr medium:A full nonlinear approach 被引量:5
2
作者 H R Baghshahi M K Tavassoly A Behjat 《Chinese Physics B》 SCIE EI CAS CSCD 2014年第7期417-428,共12页
The interaction between a two-level atom and a single-mode field in the k-photon Jaynes-Cummings model (JCM) in the presence of the Stark shift and a Kerr medium is studied. All terms in the Hamiltonian, such as the... The interaction between a two-level atom and a single-mode field in the k-photon Jaynes-Cummings model (JCM) in the presence of the Stark shift and a Kerr medium is studied. All terms in the Hamiltonian, such as the single-mode field, its interaction with the atom, the contribution of the Stark shift and the Kerr medium effects are considered to be f-deformed. In particular, the effect of the initial state of the radiation field on the dynamical evolution of some physical properties such as atomic inversion and entropy squeezing are investigated by considering different initial field states (coherent, squeezed and thermal states). 展开更多
关键词 Jaynes-Cummings model entropy squeezing atomic inversion intensity-dependent coupling
下载PDF
Shape-predicted model of spray forming rod under scanning atomization 被引量:2
3
作者 CAO Fuyang,WU Peilian,NING Zhiliang,ZHAO Wenjun,and SUN Jianfei Key Laboratory for Procession Hot Processing of Metals,Harbin Institute of Technology,Harbin 150001,China 《Rare Metals》 SCIE EI CAS CSCD 2007年第S1期30-35,共6页
A model for simulating the spray forming process with scanning atomizer was developed.Models for the scanning atomization and the deposition processes were coupled together in order to obtain a new description of the ... A model for simulating the spray forming process with scanning atomizer was developed.Models for the scanning atomization and the deposition processes were coupled together in order to obtain a new description of the spray forming process.The model,which is able to predict the shape of a spray-formed billet prepared with scanning atomizer,was established after analyzing the changes in droplet size and density distribution along the r-axis in the spray cone in scanning atomization.The effects of the two kinds of atomization were compared,showing that the scanning atomization is good for deposition. 展开更多
关键词 spray forming atomIZATION modeling rapid solidification scanning atomization
下载PDF
Entropy squeezing of an atom with a k-photon in the Jaynes-Cummings model 被引量:3
4
作者 康冬鹏 廖庆洪 +2 位作者 Ahamd Muhammad Ashfaq 王月媛 刘树田 《Chinese Physics B》 SCIE EI CAS CSCD 2010年第1期318-325,共8页
The entropy squeezing of an atom with a k-photon in the Jaynes Cummings model is investigated. For comparison, we also study the corresponding variance squeezing and atomic inversion. Analytical results show that entr... The entropy squeezing of an atom with a k-photon in the Jaynes Cummings model is investigated. For comparison, we also study the corresponding variance squeezing and atomic inversion. Analytical results show that entropy squeezing is preferable to variance squeezing for zero atomic inversion. Moreover, for initial conditions of the system the relation between squeezing and photon transition number is also discussed. This provides a theoretical approach to finding out the optimal entropy squeezing. 展开更多
关键词 Jaynes-Cumming model entropy squeezing variance squeezing atomic inversion
下载PDF
Single-atom entropy squeezing and quantum entanglement in Tavis-Cummings model with atomic motion 被引量:2
5
作者 邹艳 《Chinese Physics B》 SCIE EI CAS CSCD 2010年第7期276-283,共8页
We examine the single-atom entropy squeezing and the atom-field entanglement in a system of two moving twolevel atoms interacting with a single-mode coherent field in a lossless resonant cavity. Our numerical calculat... We examine the single-atom entropy squeezing and the atom-field entanglement in a system of two moving twolevel atoms interacting with a single-mode coherent field in a lossless resonant cavity. Our numerical calculations indicate that the squeezing period, the squeezing time and the maximM squeezing can be controlled by appropriately choosing the atomic motion and the field-mode structure. The atomic motion leads to a periodical time evolution of entanglement between the two-atom and the field. Moreover, there exists corresponding relation between the time evolution properties of the atomic entropy squeezing and that of the entanglement between the two atoms and the field. 展开更多
关键词 atomic entropy squeezing quantum reduced entropy Tavis-Cummings model atomicmotion and field-mode structure
下载PDF
Predictive models for characterizing the atomization process in pyrolysis of methyl ricinoleate 被引量:1
6
作者 Xiaoning Mao Qinglong Xie +5 位作者 Ying Duan Shangzhi Yu Xiaojiang Liang Zhenyu Wu Meizhen Lu Yong Nie 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2020年第4期1023-1028,共6页
Pyrolysis of methyl ricinoleate(MR)can produce undecylenic acid methyl ester and heptanal which are important chemicals.Atomization feeding favors the heat exchange in the pyrolysis process and hence increases the pro... Pyrolysis of methyl ricinoleate(MR)can produce undecylenic acid methyl ester and heptanal which are important chemicals.Atomization feeding favors the heat exchange in the pyrolysis process and hence increases the product yield.Herein,predictive models to characterize the atomization process were developed.The effect of spray distance on Sauter mean diameter(SMD)of atomized MR droplets was examined,with the optimal spray distance to be 40-50 mm.Temperature mainly affected the physical properties of feedstock,with smaller droplet size obtained at increasing temperature.In addition,pressure had significant influence on SMD and higher pressure resulted in smaller atomized droplets.Then,a model for SMD prediction,combining temperature,pressure,spray distance,and structural parameters of nozzle,was developed through dimensionless analysis.The results showed that SMD was a power function of Reynolds number(Re),Ohnesorge number(Oh),and the ratio of spray distance to diameter of swirl chamber in the nozzle(H/dsc),with the exponents of-1.6618,-1.3205 and 0.1038,respectively.The experimental measured SMD was in good agreement with the calculated values,with the error within±15%.Moreover,the droplet size distribution was studied by establishing the relationship between the standard deviation of droplet size and SMD.This study could provide reference to the regulation and optimization of the atomization process in MR pyrolysis. 展开更多
关键词 atomIZATION Methyl ricinoleate pyrolysis Predictive model Sauter mean diameter(SMD) Spray distance
下载PDF
Atom–field entanglement in the Jaynes Cummings model without rotating wave approximation 被引量:3
7
作者 M.Mirzaee M.Batavani 《Chinese Physics B》 SCIE EI CAS CSCD 2015年第4期70-75,共6页
In this paper, we present a structure for obtaining the exact eigenfunctions and eigenvalues of the Jaynes-Cummings model (JCM) without the rotating wave approximation (RWA). We study the evolution of the system i... In this paper, we present a structure for obtaining the exact eigenfunctions and eigenvalues of the Jaynes-Cummings model (JCM) without the rotating wave approximation (RWA). We study the evolution of the system in the strong coupling region using the time evolution operator without RWA. The entanglement of the system without RWA is investigated using the Von Neumann entropy as an entanglement measure. It is interesting that in the weak coupling regime, the population of the atomic levels and Von Neumann entropy without RWA model shows a good agreement with the RWA whereas in strong coupling domain, the results of these two models are quite different. 展开更多
关键词 atom-photon interaction Jaynes--Cummings model quantum entanglement
下载PDF
Squeezing effect of the cavity field in the two-atom Jaynes-Cummings model 被引量:2
8
作者 LIANG Jun +2 位作者 WANG Kai-ge 《原子与分子物理学报》 CAS CSCD 北大核心 2001年第4期434-438,共5页
Authors investigate the model that two two level atoms interact with a single mode cavity. The formulation of the time evolution operator for the two atom Jaynes Cummings model is presented by the bare states approach... Authors investigate the model that two two level atoms interact with a single mode cavity. The formulation of the time evolution operator for the two atom Jaynes Cummings model is presented by the bare states approach. Besides, squeezing effect of the cavity field is studied and some novel features are obtained. 展开更多
关键词 J-C模型 偶极矩 压缩 原子 相互作用
下载PDF
Calculation of Al Zn diagram from central atoms model
9
作者 Li Weimin(李卫民) Zhang Yingjiu(张迎九) 《中国有色金属学会会刊:英文版》 EI CSCD 1999年第3期611-616,共6页
A slightly modified central atoms model was proposed. The probabilities of various clusters with the central atoms and their nearest neighboring shells can be calculated neglecting the assumption of the parameter of e... A slightly modified central atoms model was proposed. The probabilities of various clusters with the central atoms and their nearest neighboring shells can be calculated neglecting the assumption of the parameter of energy in the central atoms model in proportion to the number of other atoms i (referred with the central atom). A parameter P α is proposed in this model, which equals to reciprocal of activity coefficient of α component, therefore, the new model can be understood easily. By this model, the Al Zn phase diagram and its thermodynamic properties were calculated, the results coincide with the experimental data. 展开更多
关键词 central atomS model DIAGRAM CALCULATION AL ZN
下载PDF
Photon statistical properties of the cavity field in the two-atom Jaynes-Cummings model 被引量:2
10
作者 LIANGJun WANGKai-ge 《原子与分子物理学报》 CAS CSCD 北大核心 2001年第3期309-312,共4页
The model that two two level atoms interact with a singel mode cavity is studied. The exact solution of the time evolution operator for the two atom Jaynes Cummings model is presented by the bare states approach. Furt... The model that two two level atoms interact with a singel mode cavity is studied. The exact solution of the time evolution operator for the two atom Jaynes Cummings model is presented by the bare states approach. Furthermore, we investigate the dynamical properties of the photon statistics of the cavity field, and obtain a number of novel features. 展开更多
关键词 双原子J-C模型 光子统计 空穴场
下载PDF
Opacity calculation based on average atom model 被引量:1
11
作者 SunYong-Sheng MengXu-Jun 《Nuclear Science and Techniques》 SCIE CAS CSCD 1997年第1期6-9,共4页
OpacitycalculationbasedonaverageatommodelSunYongSheng,MengXuJunandZhengShaoTang(LaboratoryofComputationalPhy... OpacitycalculationbasedonaverageatommodelSunYongSheng,MengXuJunandZhengShaoTang(LaboratoryofComputationalPhysics,Institut... 展开更多
关键词 等离子体 平均原子模型 不透明度计算
下载PDF
Atomic epn(ep) Spin Models and Spectral Lines
12
作者 Daekyoum Kim Baik-Hyon Ha 《American Journal of Analytical Chemistry》 2015年第13期1030-1037,共8页
We confirmed that how many kinds of epn spins the atoms have by calculating heat capacity of metals according to energy levels in the previous reference. To know more the spin models of epn of hydrogen and helium are ... We confirmed that how many kinds of epn spins the atoms have by calculating heat capacity of metals according to energy levels in the previous reference. To know more the spin models of epn of hydrogen and helium are imagined and their line spectra are counted. And the explanation of interference is discussed. Gas atoms make line spectra by optical interference. Solid atoms make them by exciting the lowest epns of their cluster first. They all make s, p energy orbit. One axis is composed of two epns. 1s or 2s of atoms except for lithium generally makes the symmetric axis. When each energy level is filled up by epns, these are symmetrically paired first. The atoms which fit the number of line spectra correctly by optical interference are hydrogen and helium. By counting the number of alignments of epns spins within the cluster, the atoms which fit the number of line spectra correctly are lithium, beryllium and phosphorus. The number of line spectra of the rest atoms which we have counted approaches the experimented numbers approximately, not correctly. 展开更多
关键词 atomIC model atomIC CLUSTER SPECTRAL LINES RESONANCE
下载PDF
Model of the Pulsing Atom
13
作者 Heinrich Ehrlich 《Advances in Materials Physics and Chemistry》 2017年第5期188-197,共10页
In this work, we reanalyzed the movement of an electron in the electrostatic field of nucleus. The trajectory of the electron’s motion is an ellipse with a minor semiaxis, tending towards zero. From a mathematical po... In this work, we reanalyzed the movement of an electron in the electrostatic field of nucleus. The trajectory of the electron’s motion is an ellipse with a minor semiaxis, tending towards zero. From a mathematical point of view the movement of an electron in such an orbit will be equivalent to the oscillation of an electron. The action produced by electrons in movement between stationary points is discrete and proportional to a Planck constant. This condition sets the allowable values of the electron energy and the radius of their orbit. Electrons on the same shell perform symmetric synchronous oscillations. Their frequency is of the order of 1016 Hz. Most of the time the electrons are located on the periphery of the atom, periodically they simultaneously rush to the nucleus, the atom rapidly compresses and immediately decompresses, i.e. pulsates. The model gives Bohr formula for the energy of single-electron atom and suitable values of ionization potentials of the atoms of the second period of the Periodic Table. 展开更多
关键词 atom Structure QUANTUM Theory OSCILLATION Bohr-Sommerfeld model IONIZATION POTENTIALS
下载PDF
The Atom Model of Helium and of Neon Based on the Theorem of Niels Bohr 被引量:2
14
作者 Thomas Allmendinger 《Journal of Applied Mathematics and Physics》 2018年第6期1290-1300,共11页
In a previous, primary treatise of the author the mathematical description of electron trajectories in the excited states of the H-atom could be demonstrated, starting from Bohr’s original model but modifying it thre... In a previous, primary treatise of the author the mathematical description of electron trajectories in the excited states of the H-atom could be demonstrated, starting from Bohr’s original model but modifying it three dimensionally. In a subsequent treatise, Bohr’s theorem of an unalterable angular momentum h/2π, determining the ground state of the H-atom, was revealed as an inducement by the—unalterable—electron spin. Starting from this presumption, a model of the H2-molecule could be created which exhibits well-defined electron trajectories, and which enabled computing the bond length precisely. In the present treatise, Bohr’s theorem is adapted to the atom models of helium and of neon. But while this was feasible exactly in the case of helium, the neon atom turned out to be too complex for a mathematical modelling. Nevertheless, a rough ball-and-stick model can be presented, assuming electron rings instead of electron clouds, which in the outer shell are orientated as a tetrahedron. It entails the principal statement that the neon atom does not represent a static construction with constant electron distances and velocities, but a pulsating dynamic one with permanently changing internal distances. Thus, the helium atom marks the limit for precisely describing an atom, whereby at and under this limit such a precise description is feasible, being also demonstrated in the author’s previous work. This contradicts the conventional quantum mechanical theory which claims that such a—locally and temporally—precise description of any atom or molecule structure is generally not possible, also not for the H2-molecule, and not even for the H-atom. 展开更多
关键词 Modified BOHR model Electron-Trajectories ELECTRON-SPIN Three-Dimensional atom-models Confutation of Heisenberg’s Uncertainty-Principle
下载PDF
Adaptive semi-empirical model for non-contact atomic force microscopy
15
作者 Xi Chen Jun-Kai Tong Zhi-Xin Hu 《Chinese Physics B》 SCIE EI CAS CSCD 2022年第8期682-687,共6页
Non-contact atomic force microscope is a powerful tool to investigate the surface topography with atomic resolution.Here we propose a new approach to estimate the interaction between its tips and samples,which combine... Non-contact atomic force microscope is a powerful tool to investigate the surface topography with atomic resolution.Here we propose a new approach to estimate the interaction between its tips and samples,which combines a semi-empirical model with density functional theory(DFT)calculations.The generated frequency shift images are consistent with the experiment for mapping organic molecules using CuCO,Cu,CuCl,and CuO_(x)tips.This approach achieves accuracy close to DFT calculation with much lower computational cost. 展开更多
关键词 semi-empirical model atomic force microscopy density functional theory functionalized tips
下载PDF
Effects of Atomic Mixing in Inertial Confinement Fusion by Multifluid Interpenetration Mix Model
16
作者 GU Jian-Fa YE Wen-Hua 《Communications in Theoretical Physics》 SCIE CAS CSCD 2009年第12期1102-1106,共5页
The effects of atomic-level rnixing are systemically investigated in a multifluid interpenetration mix model ,and results are compared with the single-fluid model's simulations and experimental data. It is shown that... The effects of atomic-level rnixing are systemically investigated in a multifluid interpenetration mix model ,and results are compared with the single-fluid model's simulations and experimental data. It is shown that increasing the model free parameter α, shock Mach number, and the initial density discontinuity makes the mix length and fraction of mixing particle increase, resulting in the lower shock temperatures compared with the results of single-fluid model without mixing. Recent high-compressibility direct-drive spherical implosions on OMEGA are simulated by the interpenetration mix modal. The calculations with atomic mixing between fuel and shell match quite well with the observations. Without considering any mixing, the calculated neutron yields and ion temperatures are overpredicted; while inclusion of the interpenetration mix model with the adjustable parameter α could fit the simulated neutron yields and ion temperatures well with experimental data. 展开更多
关键词 multifluid interpenetration mix model atomic mixing inertial confinement fusion
下载PDF
The Spherical Atom Model of Helium Based on the Theorem of Niels Bohr 被引量:1
17
作者 Thomas Allmendinger 《Journal of Applied Mathematics and Physics》 2019年第1期172-180,共9页
Proceeding from the double-cone model of Helium, based on Bohr’s theorem and recently published in?[13], a spherical modification could be made by introducing a second electron rotation which exhibits a rotation axis... Proceeding from the double-cone model of Helium, based on Bohr’s theorem and recently published in?[13], a spherical modification could be made by introducing a second electron rotation which exhibits a rotation axis perpendicular to the first one. Thereby, each rotation is induced by the spin of one electron. Thus the trajectory of each electron represents the superposition of two separate orbits, while each electron is always positioned opposite to the other one. Both electron velocities are equal and constant, due to their mutual coupling. The 3D electron orbits could be 2D-graphed by separately projecting them on the x/z-plane of a Cartesian coordinate system, and by plotting the evaluated x-, y- and z-values versus the rotation angle. Due to the decreased electron velocity, the resulting radius is twice the size of the one in the double-cone model. Even if distinct evidence is not feasible, e.g. by means of X-ray crystallographic data, this modified model appears to be the more plausible one, due to its higher cloud coverage, and since it comes closer to Kimball’s charge cloud model. 展开更多
关键词 Modified BOHR model Electron-Trajectories ELECTRON-SPIN 3D-atom-model Confutation of Heisenberg’s Uncertainty-Principle
下载PDF
Prediction of Radioactive Half-Lives and Atomic Nucleus Dimensions in a Concentric Shell Model or Flocon Model
18
作者 Marc Mignonat 《Journal of Modern Physics》 CAS 2022年第8期1216-1251,共36页
Considering only the wave aspect, we determine the energy of a bond between 2 nucleons;this quantified energy is associated with a standing wave. Then, starting from the mass loss corresponding to this energy, we dete... Considering only the wave aspect, we determine the energy of a bond between 2 nucleons;this quantified energy is associated with a standing wave. Then, starting from the mass loss corresponding to this energy, we determine the number of bonds in this nucleus. The mass defect value for a link is used to determine a specific length at that link. Fixing a precise distance between nucleons makes it possible to determine a geometry of the nucleus and its dimensions. It makes it possible to understand when this bond is stronger than the electrostatic force and allows deducing a shell model built in a precise order. The calculation on the mass defect will also make it possible to determine that one or more nucleons concerned by the radioactivity will be bound by a single bond to the rest of the nucleus or, on the contrary, bound by several bonds which induce short 1/2 lives or, on the contrary, very long. The analysis of the bonds on H, He and C make it possible to write formulae which are then applied to the nuclei to find the radioactive 1/2 lives. To find by equations the radioactive 1/2 lives does not call into question the standard model since it concerns only the defect of mass of the nuclei with energies that are not used to find the main particles of the standard model. This model, which favours a geometric approach to the detriment of a mathematical approach based on differential equations, can lead to theoretical questions about the possibility of interpreting the structure of the nucleus in a more undulatory way. It is possible to explain radioactivity in a more deterministic way. 展开更多
关键词 ½ Radioactive Lives atomic Nucleus Dimensions Shell model
下载PDF
The Revision of the Alleged Spherical Atom Model of Helium 被引量:1
19
作者 Thomas Allmendinger 《Journal of Applied Mathematics and Physics》 2019年第5期1212-1219,共8页
The purpose of this contribution was to evaluate a recently published atom model for Helium, characterized by a double rotation of the electrons which exhibit perpendicular rotation axes. Thereby, each rotation is ind... The purpose of this contribution was to evaluate a recently published atom model for Helium, characterized by a double rotation of the electrons which exhibit perpendicular rotation axes. Thereby, each rotation is induced by the spin of one electron?[1]. Hereto, a tangible mechanical model was used which facilitated to derive the mathematical formulae as the basics for two-dimensional projections, and—not least—for a digital animation yielding freeze images from different perspectives. The resulting shape of the electron shell turned out to be not spherical. In particular, the total velocity of the electrons is variable since the relative running direction may change—in contrast to the initial assumption—, even leading to an intermittent standstill, and implying a variable kinetic energy. Thus it can be concluded that this model describes a rotating rotor but not the Helium atom, and that it must be abandoned. 展开更多
关键词 Electron-Trajectories 2D-Projections Tangible MECHANIC atom-model 3D-Animation Rotating Rotor
下载PDF
Model of an Atom by Analogy with the Transmission Line
20
作者 Milan Perkovac 《Journal of Modern Physics》 2013年第7期899-903,共5页
Model of an atom by analogy with the transmission line is derived using Maxwell’s equations and Lorentz’ theory of electrons. To be realistic such a model requires that the product of the structural coefficient of L... Model of an atom by analogy with the transmission line is derived using Maxwell’s equations and Lorentz’ theory of electrons. To be realistic such a model requires that the product of the structural coefficient of Lecher’s transmission lines σ and atomic number Z is constant. It was calculated that this electromechanical constant is 8.27756, and we call it structural constant. This constant builds the fine-structure constant 1/α = 137.036, and with permeability μ, permittivity ε and elementary charge e builds Plank’s constant h. This suggests the electromagnetic character of Planck’s constant. The relations of energy, frequency, wavelength and momentum of electromagnetic wave in an atom are also derived. Finally, an equation, similar to Schrodinger’s equation, was derived, with a clear meaning of the wave function, which represents the electric or magnetic field strength of the observed electromagnetic wave. 展开更多
关键词 Lecher Transmission Line Lorentz’ Theory of ELECTRONS Maxwell’s Equations model of atom PLANCK CONSTANT Structural CONSTANT Transverse Mass Wave Equation
下载PDF
上一页 1 2 52 下一页 到第
使用帮助 返回顶部