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981.
We study numerically the complex domains of validity for KAM theory in generalized standard mappings. We compare methods based on Padé approximants and methods based on the study of periodic orbits. 相似文献
982.
J. J. Arenzon R. M. C. de Almeida J. R. Iglesias 《Journal of statistical physics》1992,69(1-2):385-409
A multineuron interaction model (RS model) with an energy function given by the product of the squared distances in phase space between the state of the net and the stored patterns is studied in detail within a mean-field approach. Two limits are considered: when the patterns and antipatterns are stored (as in the Hopfield model), PAS case, and when only the patterns are taken into account, OPS case. TheT=0 solutions for the proper memories are exactly obtained for all finite values of, as a consequence of the energy function: whenever one of the overlaps is exactly one the corresponding equations decouple and no configuration average is required. Special interest is focused on the OPS situation, which presents a peculiar phase space topology. On the other hand, the PAS configuration recovers the Hopfield model in the appropriate limit, while keeping associative memory abilities far beyond the critical values of other models when the full Hamiltonian is considered. 相似文献
983.
984.
Mishra SR Leung WC Arroyo C Bachmann KT Blair RE Foudas C King BJ Lefmann WC Oltman E Quintas PZ Rabinowitz SA Sciulli FJ Seligman WG Shaevitz MH Merritt FS Oreglia MJ Schumm BA Bernstein RH Borcherding F Fisk HE Lamm MJ Marsh W Merritt KW Schellman H Yovanovitch DD Bodek A Budd HS de Barbaro P Sakumoto WK Sandler PH Smith WH 《Physical review letters》1992,69(24):3499-3502
985.
986.
Marialuisa J. de Resmini 《Journal of Geometry》1982,18(1):194-198
Blocking sets in symmetric BIBD's with 2 are defined and bounds for their sizes are found. Thus, some results known in projective planes are generalized to symmetric BIBD's. 相似文献
987.
O. Costa de Beauregard 《Foundations of Physics》1982,12(9):861-871
We show that particle-antiparticle exchange and covariant motion reversal are two physically different aspects of the same mathematical transformation, either in the prequantal relativistic equation of motion of a charged point particle, in the general scheme of second quantization, or in the spinning wave equations of Dirac and of Petiau-Duffin-Kemmer. While, classically, charge reversal and rest mass reversal are equivalent operations, in the wave mechanical case mass reversal must be supplemented by exchange of the two adjoint equations, implying
.Denoting by M the rest mass reversal, P the parity reversal, T the Racah time reversal, and Z the
exchange, the connection with the usual scheme of charge conjugation, parity reversal, and Wigner motion reversal, is with, of course, 相似文献
988.
J.Th.W. de Hair 《Journal of solid state chemistry》1980,33(1):33-36
The cell constants of four new monoclinic compounds BaR4X5O17 (R = Y, Gd; X = Si, Ge) are given. The luminescence of various RE activators in the silicates is reported. Pr3+-activated BaY4Si5O17 shows efficient ultraviolet 5d → 4f emission and weak 4f → 4f emission (mainly red luminescence from the 1D2 level). The 5d → 4f emission is ascribed to Pr3+ on Y sites, the 4f → 4f emission to Pr3+ on Ba sites. Energy transfer from Pr3+ to Gd3+ has been observed. Gd3+ plays an intermediate role in the energy transfer from Pr3+ to Sm3+ and to Dy3+ in BaGd4Si5O17. Upon activation with Tb3+ the silicates show characteristic green Tb3+ luminescence with a quantum efficiency of 75% for ultraviolet excitation. 相似文献
989.
Sulfonated polystyrene latex particles were prepared by a two-stage shot-growth emulsion polymerization process in the absence of emulsifier. Sodium styrene sulfonate (NaSS) was used as an ionic co-monomer to produce a series of latex particles with the same particle size but with different surface charge densities. The electrophoretic mobility of this functionalized model colloid was studied in the presence of various types of inorganic electrolytes. The e curves of these latexes exhibit a pronounced maximum at high electrolyte concentrations: 5·10–2 M for 11 electrolytes and 10–2 M for 21 and 12 electrolytes. When a 31 electrolyte (LaCl3) was used, the electrophoretic mobility changed to positive values at high concentration due to the specific adsorption of lanthanum species. The experimental results for the electrokinetic characterization of these sulfonated polystyrene model colloids suggest that the surface of the particles is covered by a layer of oligomers or polymer chains which shift the shear plane toward the bulk solution, increasing the anomalous surface conductance of the polystyrene microsphere-electrolyte solution interface. 相似文献
990.
We have studied the efficiency of parallel tempering simulations for a variety of systems including a coarse-grained protein, an atomistic model polypeptide, and the Lennard-Jones fluid. A scheme is proposed for the optimal allocation of temperatures in these simulations. The method is compared to the existing empirical approaches used for this purpose. Accuracy associated with the computed thermodynamic quantities such as specific heat is also computed and their dependence on the trial-exchange acceptance rate is reported. 相似文献