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51.
Roberto FloreaniniLuc Vinet 《Physics letters. A》1993,180(6):393-401
Certain automorphisms of the quantum oscillator algebra are shown to provide an algebraic interpretation for q-generalizations of the Charlier polynomials. 相似文献
52.
Luciano Galeone Roberto Garrappa 《Journal of Computational and Applied Mathematics》1997,80(2):377-195
We study convergence properties of time-point relaxation (TR) Runge-Kutta methods for linear systems of ordinary differential equations. TR methods are implemented by decoupling systems in Gauss-Jacobi, Gauss-Seidel and successive overrelaxation modes (continuous-time iterations) and then solving the resulting subsystems by means of continuous extensions of Runge-Kutta (CRK) methods (discretized iterations). By iterating to convergence, these methods tend to the same limit called diagonally split Runge-Kutta (DSRK) method. We prove that TR methods are equivalent to decouple in the same modes the linear algebraic system obtained by applying DSRK limit method. This issue allows us to study the convergence of TR methods by using standard principles of convergence of iterative methods for linear algebraic systems. For a particular problem regions of convergence are plotted. 相似文献
53.
Roberto Raucci 《Rendiconti del Circolo Matematico di Palermo》1998,47(1):113-128
In this paper a two level optimization problem, in which the problem of inferior level is a Nash-problem with general constraints
(rappresented by multifunctions) and with a unique solution, is considered. On the problem of inferior level approximation
results of the solution are proved, on the problem of superior level existence and approximation results of the solutions
are proved.
相似文献
54.
Jos Vargas Carlos Ramos Roberto D. Zysler Hctor Romero 《Physica B: Condensed Matter》2002,320(1-4):178-180
Chemically prepared (CoxNi1−x)1−yBy (x=0.5, 0.75, 1; y≈0.4) amorphous fine particles were characterized by X-ray diffraction, DTA and TGA, and in situ magnetic measurement as a function of annealing temperature in an inert atmosphere. Magnetic measurement performed in as-prepared and 150°C annealed samples shows an increase of the saturation magnetization and magnetic moment after thermal treatment. Room temperature magnetization increases by factors of 3.5, 1.8, and 1.5, for x=0.5, 0.75, and 1, respectively. These measurements may indicate a local re-ordering of the amorphous phase at temperatures much lower than the full crystallization temperature. 相似文献
55.
A simple field sampling-preconcentration method for zinc determination in seawater is described. Seawater was collected in situ by pumping it through a minicolumn packed with a chelating resin (Chelite P) connected to a field flow preconcentration system (FFPS). These packed minicolumns retain the dissolved zinc, and once are loaded with the analyte, they are returned to the laboratory where they are sequentially inserted into a flow injection system for on-line zinc elution with diluted hydrochloric acid and flame atomic absorption spectrometric detection. A factorial design has been used to optimize the FFPS and the flow injection elution process. The proposed method has a linear calibration range from 0.07 to at least 9.4 microg L(-1) of zinc, with a detection limit of 0.02 microg L(-1) and a throughput of 26 samples h(-1). Validation was carried out against certified reference water samples. This procedure has been successfully applied to the determination of Zn in seawater samples from Galicia (Spain). 相似文献
56.
57.
We investigate decay properties of correlation functions in a class of chaotic billiards. First we consider the statistics of Poincaré recurrences (induced by a partition of the billiard): the results are in agreement with theoretical bounds by Bunimovich, Sinai, and Bleher, and are consistent with a purely exponential decay of correlations out of marginality. We then turn to the analysis of the velocity-velocity correlation function: except for intermittent situations, the decay is purely exponential, and the decay rates scale in a simple way with the (uniform) curvature of the dispersing arcs. A power-law decay is instead observed when the system is equivalent to an infinite-horizon Lorentz gas. Comments are given on the behaviour of other types of correlation functions, whose decay, during the observed time scale, appears slower than exponential. 相似文献
58.
Roberto H. Schonmann 《Communications in Mathematical Physics》1989,124(1):1-7
Consider the + phase of the two dimensional nearest neighbor ferromagnetic Ising model at a temperature belowT
c
. Let + be the restriction of this measure to a coordinate axis. We prove that there is no one dimensional translation invariant summable interaction for which + is a Gibbs measure. This is proven by showing that if such an interaction existed, + would have large deviation properties different from those it actually has. Percolation methods are used in the proof.Work supported by the U.S. Army Research Office through the Mathematical Sciences Institute at Cornell and by a NSF grant to Cornell. This work was finished while the author was visiting Rutgers University, being supported by the NSF grant 86-12369 相似文献
59.
Gutiérrez de Dios FJ Gómez R Feliu JM 《Langmuir : the ACS journal of surfaces and colloids》2005,21(16):7439-7448
Rhodium adlayers on Pt(100) substrates have been prepared by electrodeposition from dilute Rh(III) acidic solutions. The initially disordered layer is electrochemically annealed by applying a polarization program consisting of high-sweep-rate multicycle sequences between 0.05 and 0.78 V(RHE) in 0.1 M H(2)SO(4). In this way, a pseudomorphic Rh monolayer can be prepared on Pt(100) substrates. The degree of order of the electrochemically annealed layer has been evidenced not only through voltammetric experiments but also by means of scanning tunneling microscopy with atomic resolution for iodine-protected adlayers, which show a c(2 x 2) structure. The electrochemically induced ordering of the Rh adlayer appears to be a consequence of the repeated cycles of adsorption/desorption of H and, especially, oxygenated species. Voltammetry in sulfuric acid solutions permits examination of the energetics of H/anions and OH/O adsorption as a function of the Rh coverage. The first monolayer adsorbs both hydrogen and oxygenated species more strongly than the second one. This can be explained through an electronic effect caused by the underlying Pt(100) substrate. 相似文献
60.
Substrate relaxation is shown to play an important role in the 1 : 2 regular chemisorption of hydrogen atoms above alternate carbon atoms in a graphite monolayer. Binding energy, population analysis and electron density maps show that the direct HC bond is strengthened on relaxation. 相似文献