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排序方式: 共有1609条查询结果,搜索用时 78 毫秒
901.
902.
903.
The conductance of ionic species through a cylindrical nanochannel is explored by means of a mesoscopic lattice Boltzmann numerical method. It is shown that in the absence of any external voltage, the ionic profiles develop a considerable amount of structure within the channel. The details of this structure depend on the ionic density, channel length, and Debye length. In the presence of a trans-membrane electrostatic potential, less structure is observed and Ohm's law is found to hold. 相似文献
904.
905.
Let
be the Haag--Kastler net generated by the
(2) chiral current algebra at level 1. We classify the SL(2,
)-covariant subsystems
by showing that they are all fixed points nets
H
for some subgroup H of the gauge automorphisms group SO(3) of
. Then, using the fact that the net
1 generated by the
(1) chiral current can be regarded as a subsystem of
, we classify the subsystems of
1. In this case, there are two distinct proper subsystems: the one generated by the energy-momentum tensor and the gauge invariant subsystem
. 相似文献
906.
A ditopic palladacycle with SCS pincer coordination, L(PdCl)(2) (1), was isolated and structurally characterized and represents the first example of a transition metal complex with a polythioamide-based macrocycle. Preliminary studies of 1 in the catalytic coupling of 4-iodotoluene and styrene indicated it to be robust in the presence of oxygen and high temperatures, with high turnover numbers in relatively short times. 相似文献
907.
908.
The dynamics of the pairwise entanglement in a qubit lattice in the presence of static imperfections exhibits different regimes. We show that there is a transition from a perturbative region, where the entanglement is stable against imperfections, to the ergodic regime, in which a pair of qubits becomes entangled with the rest of the lattice and the pairwise entanglement drops to zero. The transition is almost independent of the size of the quantum computer. We consider both the case of an initial maximally entangled and separable state. In this last case there is a broad crossover region in which the computer imperfections can be used to create a significant amount of pairwise entanglement. 相似文献
909.
Discretization of phase space usually nullifies chaos in dynamical systems. We show that if randomness is associated with discretization dynamical chaos may survive and be indistinguishable from that of the original chaotic system, when an entropic, coarse-grained analysis is performed. Relevance of this phenomenon to the problem of quantum chaos is discussed. 相似文献
910.
Dissimilar material joining using laser (aluminum to steel using zinc-based filler wire) 总被引:9,自引:0,他引:9
Alexandre Mathieu Rajashekar Shabadi Alexis Deschamps Michel Suery Simone Matteï Dominique Grevey Eugen Cicala 《Optics & Laser Technology》2007,39(3):652-661
Joining steel with aluminum involving the fusion of one or both materials is possible by laser beam welding technique. This paper describes a method, called laser braze welding, which is a suitable process to realize this structure. The main problem with thermal joining of steel/aluminum assembly with processes such as TIG or MIG is the formation of fragile intermetallic phases, which are detrimental to the mechanical performances of such joints. Braze welding permits a localized fusion of the materials resulting in a limitation on the growth of fragile phases. This article presents the results of a statistical approach for an overlap assembly configuration using a filler wire composed of 85% Zn and 15% Al. Tensile tests carried on these assemblies demonstrate a good performance of the joints. The fracture mechanisms of the joints are analyzed by a detailed characterization of the seams. 相似文献