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161.
仝道荣 《河海大学学报(自然科学版)》1991,(2)
在这篇文章中我们讨论了一个半序集的内禀拓扑的紧性和连通性,以及内禀拓扑与其在子集中的导出拓扑之间的关系,主要结果有:1.格L的区间拓扑是紧的,当且仅当L是备的;2.局部有限散度半序集P的区间拓扑是连通的,当且仅当P是稠的且条件备;3.格L中设M=[←,p],则M的区间拓扑(开区间拓扑)和L的区间拓扑(开区间拓扑)在M的导出拓扑等价. 相似文献
162.
库热西·沙吾提 《新疆大学学报(理工版)》1998,(1)
本文将引入负偏序半群的Fuzzy序滤子的概念,并研究Fuzzy序滤子成为序滤子的充要条件及Fuzzy序滤子的结构性质 相似文献
163.
研究了超短光脉冲在GaAs表面激发相干亚毫米波振幅随入射角变化的规律,前后向辐射比值随入射角度变化的规律,实验测量了GaAs表面镀上极薄金属薄膜后产生的相干亚毫米波振幅对薄膜厚度的依赖关系,利用光生载子偶极辐射的理论模型成功地解释了实验得到的角度依赖关系和相干亚毫米波的偏振特性。 相似文献
164.
165.
A. Sinatra Y. Castin 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,4(3):247-260
In the absence of losses the phase of a Bose-Einstein condensate undergoes collapses and revivals in time due to elastic atomic
interactions. As experiments necessarily involve inelastic collisions, we develop a model to describe the phase dynamics of
the condensates in presence of collisional losses. We find that a few inelastic processes are sufficient to damp the revivals of the phase. For this reason the observability of phase revivals for present experimental
conditions is limited to condensates with a few hundreds of atoms.
Received: 23 February 1998 / Revised: 21 July 1998 / Accepted: 23 July 1998 相似文献
166.
A coherent potential approximation (cpa) for a mixed diatomic linear chain including both mass and force constant changes has been developed. In this case an impurity
atom substituted at a particular site in one of the sublattices couples with two nearest neighbour atoms in the other sublattices.
The diatomic linear chain is therefore considered as a tetratomic linear chain, the size of the unit cell being twice the
original. Thecpa density of states and the dielectric susceptibility have been calculated. The numerical values of the later have been calculated
in theata (averaget-matrix approximation) limit. Comparison of these results with the experimental and other computer calculations show a qualitative
agreement. 相似文献
167.
Ji-Suo Wang Tang-Kun Liu Jian Feng Jin-Zuo Sun 《International Journal of Theoretical Physics》2004,43(9):1891-1905
A class of k-quantum nonlinear coherent states, i.e., the k eigenstates of the powers B
k
(k 3) of the annihilation operator
of f-oscillators, is obtained and its completeness is investigated. An alternative method to construct them is proposed. We introduce a new kind of higher-order squeezing and sub-Poissonian distribution. The quantum statistical properties of the k states are studied. The result shows that all of the eigenstates can be generated by a linear superposition of k Roy-type nonlinear coherent states. These states may form a complete Hilbert space, and the M-th order [M = (n + 1/2)k; n = 0,1, ...] squeezing effects exist in all of the k states when k is even. There is the sub-Poissonian distribution in all of the states. 相似文献
168.
Lü Baida & PAN Liuzhan . Institute of Laser Physics Chemistry Sichuan University Chengdu China . Department of Physics Luoyang Normal College Luoyang China . State Key Laboratory of Laser Technology Huazhong University of Science Technology Wuhan China Correspondence should be addressed to L Baida 《中国科学G辑(英文版)》2004,47(1):24-35
Inrecentyearsanewbranchofmodernphysicalopticscalledsingularoptics[1]hasbeendeveloped.In2002theworkinsingularopticswasextendedfrommonochromaticlighttospatiallyfullycoherentandpolychromaticlightbyGburetal.[2—4].Itwasfoundthat,whenaconverging,spatiallyfullycoherentandpolychromaticsphericalwaveisdiffractedatanaperture,anomalousspectralchangestakeplaceclosetozerosoftheintensityinthefarfield;i.e.thespectrumisredshiftedatsomepoints,blueshiftedatothers,andsplitintotwolineselsewhere.Thepredictionsofsp… 相似文献
169.
It will be shown that a normed partially ordered vector space is linearly, norm, and order isomorphic to a subspace of a normed Riesz space if and only if its positive cone is closed and its norm p satisfies p(x)p(y) for all x and y with -yxy. A similar characterization of the subspaces of M-normed Riesz spaces is given. With aid of the first characterization, Krein's lemma on directedness of norm dual spaces can be directly derived from the result for normed Riesz spaces. Further properties of the norms ensuing from the characterization theorem are investigated. Also a generalization of the notion of Riesz norm is studied as an analogue of the r-norm from the theory of spaces of operators. Both classes of norms are used to extend results on spaces of operators between normed Riesz spaces to a setting with partially ordered vector spaces. Finally, a partial characterization of the subspaces of Riesz spaces with Riesz seminorms is given. 相似文献
170.
The Boson Normal Ordering Problem and Generalized Bell Numbers 总被引:2,自引:0,他引:2
For any function F(x) having a Taylor expansion we solve the boson
normal ordering problem for $F [(a^\dag)^r a^s]$, with r, s positive integers,
$F [(a, a^\dag]=1$, i.e., we provide exact and explicit
expressions for its normal form $\mathcal{N} \{F [(a^\dag)^r a^s]\} = F [(a^\dag)^r a^s]$, where
in $ \mathcal{N} (F) $ all a's are to the
right. The solution involves integer sequences of numbers which, for $ r, s \geq 1 $, are
generalizations of the conventional Bell and Stirling numbers whose values they assume for $ r=s=1 $. A complete
theory of such generalized combinatorial numbers is given including closed-form expressions
(extended Dobinski-type formulas), recursion relations and generating functions. These last are
special expectation values in boson coherent states.AMS Subject Classification: 81R05, 81R15, 81R30, 47N50. 相似文献