检索结果-南通市图书馆

Orbital Interaction of Epoxidation on the Same Curvature Bonds of Single-walled Carbon Nanotubes

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Structural Chemistry 2007年第11期26卷 1308-1314页

作者：贾桂霄李俊篯李奕陈林刚陈勇 department of Chemistry Fuzhou University

The epoxidation of different bonds with the same bond curvature in one nanotube including armchair, zigzag and chiral tubes was studied. The calculated results showed that for the adducts with opened C-O--C configuration, the magnitude of the binding energies was related with their corresponding bonding characteristics in HOMO, and the larger binding energies were attributed to stronger orbital interaction between one O atom and the nanotube; whereas for the adducts with 3MR structures, the binding energies were related with the changes of C-C bond length and independent of the frontier orbital interaction before and after epoxidation.

关键词： carbon nanotube epoxidation bond curvature orbital interaction

Dark soliton in one-dimensional Bose-Einstein condensate under a periodic perturbation of trap

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2011年第1期20卷 150-156页

作者：刘超飞胡柯胡涛唐翌 department of Physics Xiangtan University

The perturbation of a confining trap leads to the collective oscillation of a Bose-Einstein condensate, thereby the propagation of a dark soliton in the condensate is affected. In this study, periodic perturbation is employed to match the soliton oscillation. We find that the soliton dynamics depends sensitively on the coupling between the moving direction of the trap and that of the soliton. The soliton energy/depth evolves periodically, and a relevant shift in the soliton trajectory occurs as compared with the unperturbed case. Overall, the soliton oscillation frequency changes little even if the perturbation amplitude and frequency vary.

关键词： Bose-Einstein condensate dark soliton

Finite size effect of ions and dipoles close to charged interfaces

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2010年第4期19卷 469-477页

作者：童朝晖诸跃进 department of Physics Ningbo University

The modified dipolar Poisson-Boltzmann （MDPB） equation, where the electrostatics of the dipolar interactions of solvent molecules and also the finite size effects of ions and dipolar solvent molecules are explicitly taken into account on a mean-field level, is studied numerically for a two-plate system with oppositely charged surfaces. The MDPB equation is solved numerically, using the nonlinear Multigrid method, for one-dimensional finite volume meshes. For a high enough surface charge density, numerical results of the MDPB equation reveal that the effective dielectric constant decreases with the increase of the surface charge density. Furthermore, increasing the salt concentration leads to the decrease of the effective dielectric constant close to the charged surfaces. This decrease of the effective dielectric constant with the surface charge density is opposite to the trend from the dipolar Poisson Boltzmann （DPB） equation. This seemingly inconsistent result is due to the fact that the mean-field approach breaks down in such highly charged systems where the counterions and dipoles are strongly attracted to the charged surfaces and form a quasi two-dimensional layer. In the weak-coupling regime with the electrostatic coupling parameter （the ratio of Bjerrum length to Gouy-Chapman length） Ξ 〈 1, where the MDPB equation works, the effective dielectric constant is independent of the distance from the charged surfaces and there is no accumulation of dipoles near the charged surfaces. Therefore, there are no physical and computational advantages for the MDPB equation over the modified Poisson-Boltzmann （MPB） equation where the effect of dipolar interactions of solvent dipoles is implicitly taken into account in the renormalised dielectric constant.

关键词： dipole Poisson Boltzmann equation charged interface polarisation

Effects of anisotropy and magnetic fields on the specific heat of a quasi-two-dimensional Boltzmann gas in an elliptical parabolic quantum dot

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2012年第7期21卷 201-206页

作者：翟智远李玉奇潘孝胤 department of Physics Ningbo University

We investigate the effects due to anisotropy and magnetic field interaction for a quasi-two-dimensional Boltzmann gas in an elliptical parabolic quantum dot. The specific heat is studied with varying temperature, anisotropy, and magnetic field strength. The cases without and with the inclusion of the spin Zeeman interaction are considered.

关键词： specific heat Zeeman interaction anisotropy harmonic oscillator

Heat transport in coupled inhomogeneous chains

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2011年第6期20卷 125-130页

作者：胡涛白萌胡柯唐翌 department of Physics Xiangtan University

We first investigate the heat transport in a network model consisting of two coupled dimerized chains. Results indicate that the thermal resistance of each chain increases with the decrease of the mass ratio γ. of the two types of atoms. Then, we find, when a light impurity or a heavy one is added in the two coupled homogeneous chains and coupled with a particle of another chain, the interface thermal resistances Rint and Rint present different dependences on the mass ratio γ Finally, a persistent circulation of energy current is observed in coupled inhomogeneous chains with two pairs of interchain coupling.

关键词： heat transport thermal resistance

Density-dependent photoabsorption cross sections of atomic Xe

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2009年第1期18卷 161-166页

作者：马晓光 department of Physics Ludong University

The evolution of the photoabsorption cross sections of atomic xenon with number densities varying from ideal gas to condensed matter has been studied by an alternative view in the present work. The alternative expressions of the photoabsorption cross sections presented by Sun et al recently were used with the local field models that has proven to be generalized easily to multiatoinic systems including molecules and condensed phase systems. The present results show that the variation of the photoabsorption cross sections of atomic xenon in the giant resonance region from the isolated to the condensed conditions is very small, which agrees well with the variation law of the solid and gas experiments.

关键词： condensed-phase photoabsorption local field xenon

Rigidity based formation tracking for multi-agent networks

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2015年第9期24卷 62-67页

作者：白璐陈飞兰维瑶 department of Automation Xiamen University

This paper considers the formation tracking problem under a rigidity framework, where the target formation is specified as a minimally and infinitesimally rigid formation and the desired velocity of the group is available to only a subset of the agents. The following two cases are considered： the desired velocity is constant, and the desired velocity is timevarying. In the first case, a distributed linear estimator is constructed for each agent to estimate the desired velocity. The velocity estimation and a formation acquisition term are employed to design the control inputs for the agents, where the rigidity matrix plays a central role. In the second case, a distributed non-smooth estimator is constructed to estimate the time-varying velocity, which is shown to converge in a finite time. Theoretical analysis shows that the formation tracking problem can be solved under the proposed control algorithms and estimators. Simulation results are also provided to show the validity of the derived results.

关键词： multi-agent system formation control graph rigidity distributed estimator

Finite size effects on the helical edge states on the Lieb lattice

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2016年第6期25卷 444-457页

作者：陈锐周斌 department of Physics Hubei University

For a two-dimensional Lieb lattice,that is,a line-centered square lattice,the inclusion of the intrinsic spin–orbit（ISO）coupling opens a topologically nontrivial gap,and gives rise to the quantum spin Hall（QSH） effect characterized by two pairs of gapless helical edge states within the bulk ***,due to the finite size effect in QSH systems,the edge states on the two sides of a strip of finite width can couple together to open a gap in the *** this paper,we investigate the finite size effect of helical edge states on the Lieb lattice with ISO coupling under three different kinds of boundary conditions,i.e.,the straight,bearded and asymmetry *** spectrum and wave function of edge modes are derived analytically for a tight-binding model on the Lieb *** a strip Lieb lattice with two straight edges,the ISO coupling induces the Dirac-like bulk states to localize at the edges to become the helical edge states with the same Dirac-like ***,it is found that in the case with two straight edges the gapless Dirac-like spectrum remains unchanged with decreasing the width of the strip Lieb lattice,and no gap is opened in the edge *** is concluded that the finite size effect of QSH states is absent in the case with the straight ***,in the other two cases with the bearded and asymmetry edges,the energy gap induced by the finite size effect is still opened with decreasing the width of the *** is also proposed that the edge band dispersion can be controlled by applying an on-site potential energy on the outermost atoms.

关键词： quantum spin Hall state finite size effect spin–orbit coupling Lieb lattice

Solvent induced shape change in CePO_4:Dy^(3+) nanophosphors and effect of metal ions: A photoluminescence study

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2012年第12期30卷 1217-1224页

作者： Reena Okram N.Rajmuhon Singh department of Chemistry Manipur University

The influence of different solvents and metal ions （Li^＋, Ba^2＋, Bi^3＋） on the crystallization behaviour, morphology and enhancement in photoluminescence intensity of Dy^3＋ doped CePO4 were investigated. Highly crystalline luminescent nanophosphors of CePO4：DY^3＋ re-dispersible in polar solvents were successfully prepared via a simple polyol route at 140 ℃. As-prepared Dy^3＋ doped CePO4 nanophosphors prepared in EG and DMF appeared to have crystalline monoclinic phase but exhibited hexagonal phase when prepared in water and water mixed solvents, The hexagonal phase transformed to monoclinic phase after heating at 900 ℃. TEM study revealed different shapes of the synthesized nanophosphors with change of solvents. The luminescence intensity of 4F9/2→6H15/2 at 478 nm （blue） was found to be more prominent than 4F9/2→6H13/2 at 572 nm （yellow）. The introduction of metal ions （Li＋, Ba2＋ and Bi3＋） in CePO4：Dy3＋ led to considerable luminescent enhancement. The nanophosphors were subsequently incorporated in polymer films of PVA which showed the characteristic emissions of Dy3＋. It also served as an effective method to improve the performance of polymer materials and brought about novel properties in them.

关键词： enhanced luminescence rare earth point defects nanophosphor re-dispersible