Dynamics of the current-driven Josephson junction

The irreversible macroscopic dynamics of the Josephson junction coupled to external wires acting as a current source is derived rigorously from the underlying microscopic Hamiltonian quantum mechanics. The external systems are treated in the singular coupling limit. The use of this limit is explicitly justified via an interpretation of the singular coupling limit in terms of the relative magnitudes of system, reservoir, and coupling energies. The qualitative behavior of the macroscopic dynamical equations is shown to depend sensitively and crucially on the interaction between the wires and the superconductors and on the size of the wires: the dc Josephson effect only happens when one lets Cooper pairs be driven into the junction by collective (i.e., small) reservoirs.     

卤代化合物的碳—13化学位移模拟

用人工神经网络和多元回归方法对含２个碳的２１个卤代化合物的３５个化学位移进行计算机图像模拟，结果表明，人工神经网络方法优于多元回归方法，同时此种方法处理这类问题有明显的优势，波谱模拟技术在有机化合物结构解析中是非常有用的方法。     

Synthesis on the basis of electrogenerated carbenes

A series ofS _N2 reactions with halomethanes as substrates and the corresponding anions as nucleophiles were studied by the semiempirical MNDO and AM1 methods, taking into account solvent effects. Analysis of the kinetics, structures of reagents, intermediates and products, and charge distribution in them allows one to draw the conclusion that the retardation ofS _N2 reactions is stronger in solvents than in the gas phase, and the rates of reactions involving anions with a lower number of halogen atoms are higher.For Part 8 see Ref. 1.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2148–2154, November, 1995.This work was partially financially supported by the International Science Foundation (Grant No. MHYOO).     

Simulation of aerated lagoon using artificial neural networks and multivariate regression techniques

The aim of this study was to develop an empirical model that provides accurate predictions of the biochemical oxygen demand of the output stream from the aerated lagoon at International Paper of Brazil, one of the major pulp and paper plants in Brazil. Predictive models were calculated from functional link neural networks (FLNNs), multiple linear regression, principal components regression, and partial least-squares regression (PLSR). Improvement in FLNN modeling capability was observed when the data were preprocessed using the PLSR technique. PLSR also proved to be a powerful linear regression technique for this problem, which presents operational data limitations.     

Lifschitz singularities for periodic operators plus random potentials

UsingX-bounding (lower bounds by Laplacians with mixed boundary conditions and discrete analogs), we obtain the Lifschitz exponent at the bottom of the spectrum for random operators of typeH =T+V , withT a (periodic) generator of a positivity-preserving semigroup, extending results by Kirsch and Simon.     

Dynamics of intramolecular processes in electronic-excited states of 2,4,5-triarylimidazole molecules

Intramolecular processes in electronic-excited states of 2,4,5-triarylimidazole molecules were studied by femtosecond laser spectroscopy. Experiments were carried out with two types of compounds, namely, those experiencing intramolecular proton transfer and two model compounds in which it is impossible. Schemes of the processes studied were proposed and the characteristic rate constants were determined. The excited-state intramolecular proton transfer (ESIPT) in the molecules with planar structure of the reaction center is a very fast process (100 fs). If the reaction center has a nonplanar structure and, hence, the intramolecular hydrogen bond is weakened, the ESIPT time is determined by the time of conformational rearrangement of the molecule.     

NH_2基态和激发态的SAC－CI和量子拓扑方法研究

ＮＨ_２基态和激发态的ＳＡＣ－ＣＩ和量子拓扑方法研究郑世钧，蔡新华，宋天乐，孟令鹏，中迁博，波田雅彦（河北师范学院化学系，石家庄，０５００９１）（京都大学工程学院京都，日本）关键词ＳＡＣ－ＣＩ方法，激发态，电子密度，拓扑分析用量子拓扑学方法研究激发态...     

In search of new resonance structures in dissociative photoionization of H2

We present a theoretical study of dissociative photoionization of H₂ via the ¹Π_u symmetry in the photon energy range 30–43 eV. Our results explain the various peaks observed in the experiments below 40 eV and illustrate, in particular, the important role of the ²Π_u(2pπ_u) ionization threshold. At higher photon energies, they suggest the existence of new resonance structures that may be associated with doubly excited states of H₂ lying above the third and fourth ionization thresholds (the Q₃ and Q₄ resonance series). From the calculated resonance parameters, we conclude that the dominant mechanism at high photon energies should involve the Q₄ (and probably higher) doubly excited states of H₂. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2002