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61.
S.G.F. Martins T.J.P. Penna P.M.C. de Oliveira 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,9(3):559-565
In this work we propose an evolution model based on the competition between individuals belonging to populations of neural
networks, obeying the Hopfield dynamics. The selection rule adopted relies on generalization and natural classification abilities.
The results obtained through computer simulation show that these populations self-organize and evolve towards equilibrium
states in the region of transition between ordered and disordered phases.
Received 28 October 1998 and Received in final form 2 December 1998 相似文献
62.
We address the problem of observables in generally invariant spacetime theories such as Einstein’s general relativity. Using
the refined notion of an event as a “point-coincidence” between scalar fields that completely characterise a spacetime model,
we propose a generalisation of the relational local observables that does not require the existence of four everywhere invertible
scalar fields. The collection of all point-coincidences forms in generic situations a four-dimensional manifold, that is naturally
identified with the physical spacetime. 相似文献
63.
64.
T. Krüger 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,14(3):299-307
Suppose that a pair of entities which have been generated jointly from a common source are separated by an experimental device
so that they cannot interact any more. Then, strictly formulating within the framework of traditional quantum mechanics, the
ensemble of all pairs may be represented by either a separable or a non-separable statistical operator. The former stands for the independence of the sub-ensembles whereas the latter admits correlations
(EPR correlations) due to the presence of interference or cross terms. The second-order correlation function Δ, which is also
amenable by experiment, adopts different values depending on the choice of the statistical operator. So, by performing an
experiment of this kind with molecules, the question could be decided whether EPR correlations appear in the molecular domain
too. A detailed elaboration of the following idea is presented: let an achiral precursor molecule M2 dissociate so that two chiral fragments of different handedness are obtained. After separation R-M (L-M) interacts in a region
of space A (B) with a photon I (II) in an already known linear polarization state. The enantiomeric correlation between the
fragments is thereby conferred to the photons, and the corresponding changes of the polarization state are detected for different
polarizer settings to finally yield Δ.
Received 10 May 2000 and Received in final form 25 August 2000 相似文献
65.
Quantum mechanical ab initio simulation of the electron screening effect in metal deuteride crystals
A. Huke K. Czerski S. M. Chun A. Biller P. Heide 《The European Physical Journal A - Hadrons and Nuclei》2008,35(2):243-252
In antecedent experiments the electron screening energies of the d+d reactions in metallic environments have been determined
to be enhanced by an order of magnitude in comparison to the case of gaseous deuterium targets. The analytical models describing
averaged material properties have not been able to explain the experimental results so far. Therefore, a first effort has
been undertaken to simulate the dynamics of reacting deuterons in a metallic lattice by means of an ab initio Hartree-Fock calculation of the total electrostatic force between the lattice and the successively approaching deuterons
via path integration. The calculations have been performed for Li and Ta, clearly showing a migration of electrons from host
metallic to the deuterium atoms. However, in order to avoid more of the necessary simplifications in the model the utilization
of a massive parallel supercomputer would be required. 相似文献
66.
Xiao Qian WANG Shi Hong CHENG 《数学学报(英文版)》2005,21(5):1121-1130
In Part Ⅰ the concept of the general regular variation of n-th order is proposed and its construction is discussed. The uniqueness of the standard expression and the higher order regularity of the auxiliary functions are proved. 相似文献
67.
Integer linear programming (ILP) problems occur frequently in many applications. In practice, alternative optima are useful since they allow the decision maker to choose from multiple solutions without experiencing any deterioration in the objective function. This study proposes a general integer cut to exclude the previous solution and presents an algorithm to identify all alternative optimal solutions of an ILP problem. Numerical examples in real applications are presented to demonstrate the usefulness of the proposed method. 相似文献
68.
C. Buzano 《Il Nuovo Cimento D》1989,11(10):1415-1426
Summary The system considered consists of spin-1 objects arranged on a three-dimensional lattice. It is characterized by an anisotropic
Blume-Emery-Griffiths Hamiltonian in which the dipolar and quadrupolar intrachain coupling constants are much stronger than
the corresponding interchain coupling constants so that the system can be considered quasi-one-dimensional. The method of
analysis utilizes first the exact solution of the one-dimensional case and then the Bogolubov variational principle. The critical
properties are examined and the phase diagram derived.
Riassunto Il sistema considerato consiste di oggetti a spin-1 disposti su un reticolo tridimensionale ed è caratterizzato da una Hamiltoniana anisotropa in cui le costanti dipolari e quadrupolari di accoppiamento all’interno delle catene sono molto maggiori delle corrispondenti costanti di accoppiamento fra catene, cosicché il sistema può essere considerato quasi unidimensionale. Il metodo di analisi impiegato utilizza anzitutto la soluzione esatta del caso unidimensionale e successivamente il principio variazionale di Bogolubov. Si esaminano le proprietà critiche e si ricava il diagramma di fase.
Резюме Рассматривается система, которая состоит из объектов со спином 1, образующих трехмерную решетку. Эта система характеризуется Гамильтонианом Ълуме-Эмери-Гриффитса, в котором дипольные и квадрапольные внутрицепочечные постоянные связи являются более сильными, чем соответствующие постоянные связи между цепочками, так что система может быть рассмотрена, как квази-одномерная. Метод анализа использует сначала точное решение для одномерного случая, а затем вариационный принцип Ъоголюбова. Исслеледуются критические свойства и выводится фазовая диаграмма.相似文献
69.
70.
Agnes Voitl Alessandro Butté Massimo Morbidelli 《Journal of chromatography. A》2010,1217(34):5492-5500
Experiments with human serum albumin on a strong cation exchange resin exhibit a peculiar elution pattern: the protein elutes with two peaks in a modifier gradient. This behavior is modeled with a general rate model, where the two elution peaks are modeled with two binding conformations, one of which is at equilibrium conditions, while for the other, the adsorption process is rate limited. Isocratic experiments under nonadsorbing conditions were used to characterize the mass transfer process. The isotherm of both adsorption conformations as well as the kinetic of adsorption and desorption for the second conformation are functions of the modifier concentration. They are evaluated with linear modifier gradient experiments and step experiments with various adsorption times. All experimental features are well reproduced by the proposed modified general rate model. 相似文献