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61.
The behavior of the slip length in thin polymer films subject to planar shear is investigated using molecular dynamics simulations. At low shear rates, the slip length extracted from the velocity profiles correlates well with that computed from a Green-Kubo analysis. Beyond chain lengths of about N=10, the molecular weight dependence of the slip length is dominated strongly by the bulk viscosity. The dynamical response of the slip length with increasing shear rate is well captured by a power law up to a critical value where the momentum transfer between wall and fluid reaches its maximum. 相似文献
62.
Parthey CG Matveev A Alnis J Bernhardt B Beyer A Holzwarth R Maistrou A Pohl R Predehl K Udem T Wilken T Kolachevsky N Abgrall M Rovera D Salomon C Laurent P Hänsch TW 《Physical review letters》2011,107(20):203001
We have measured the 1S-2S transition frequency in atomic hydrogen via two-photon spectroscopy on a 5.8 K atomic beam. We obtain f(1S-2S) = 2,466,061,413,187,035 (10) Hz for the hyperfine centroid, in agreement with, but 3.3 times better than the previous result [M. Fischer et al., Phys. Rev. Lett. 92, 230802 (2004)]. The improvement to a fractional frequency uncertainty of 4.2 × 10(-15) arises mainly from an improved stability of the spectroscopy laser, and a better determination of the main systematic uncertainties, namely, the second order Doppler and ac and dc Stark shifts. The probe laser frequency was phase coherently linked to the mobile cesium fountain clock FOM via a frequency comb. 相似文献
63.
Andréi Zaitsevskii Elena Rykova Nikolai S. Mosyagin Anatoly V. Titov 《Central European Journal of Physics》2006,4(4):448-460
The relativistic effective core potential (RECP) approach combined with the spin-orbit DFT electron correlation treatment
was applied to the study of the bonding of eka-mercury (E112) and mercury with hydrogen and gold atoms. Highly accurate small-core
shape-consistent RECPs derived from Hartree-Fock-Dirac-Breit atomic calculations with Fermi nuclear model were employed. The
accuracy of the DFT correlation treatment was checked by comparing the results in the scalar-relativistic (spin-orbit-free)
limit with those of high level scalar-relativistic correlation calculations within the same RECP model. E112H was predicted
to be slightly more stable than its lighter homologue (HgH). The E112-Au bond energy is expected to be ca. 25–30 % weaker
than that of Hg-Au. The role of correlations and magnetic (spin-dependent) interactions in E112-X and Hg-X (X=H, Au) bonding
is discussed. The present computational procedure can be readily applied to much larger systems and seems to be a promising
tool for simulating E112 adsorption on metal surfaces. 相似文献
64.
Nikolai Kiselev Vera Rosenbush Ludmilla Kolokolova Kirill Antonyuk 《Journal of Quantitative Spectroscopy & Radiative Transfer》2008,109(8):1384-1391
We have found an anomalous (negative) spectral dependence of polarization for split comet 73P/Schwassmann–Wachmann 3, i.e. polarization degree in the I filter is systematically less (4%) than that in the R filter for both B and C subnuclei of the comet. Earlier we revealed a similar effect for comets 21P/Giacobini–Zinner, C/1999 S4 (LINEAR), and 9P/Tempel 1. Together with comet C/1989 X1 (Austin), for which the similar spectral dependence of polarization was also observed, these comets form a group characterized by some peculiar properties of their dust. Since atypical organic composition is a characteristic feature for all these comets, the anomalous spectral dependence of polarization may indicate specifics of origin of these comets. Really, most of these comets (but not all) originated from the Kuiper Belt. Also, most (but not all) of these comets belong to the group of comets depleted in carbon species in the gas phase, which is typical for comets formed in the giant-planet area of the solar system. On the other hand, all of the comets with negative spectral gradient of polarization have the dust dominated by large particles and most of them belong to the Jupiter family. This may indicate that anomalous spectral dependence of their polarization is a result of their evolution. To identify the reason of anomalous polarization, systematic spectropolarimetric observations of Jupiter-family comets are necessary. 相似文献
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68.
Michail I. Alymov Nikolai M. Rubtsov Boris S. Seplyarskii Victor A. Zelensky Alexey B. Ankudinov Georgii I. Tsvetkov Victor I. Chernysh 《Mendeleev Communications》2018,28(4):447-449
It was shown that the synthesis of Cu nanopowder by thermal decomposition afforded chemically purer (without oxides) and finer (specific surface value ~45 m2 g?1) product than the synthesis by chemical reduction. The latter method leads to pyrophoric nanopowders containing detectable amounts of copper oxides. 相似文献
69.
Nikolai A.Magnitskii 《PAMM》2007,7(1):2040033-2040034
It is shown that there exists one universal scenario of transition to chaos in three considered systems of nonlinear partial differential equations of diffusion type. It is the subharmonic cascade of bifurcations of two-dimensional tori along one or both frequencies. So, it is shown that the new universal Feigenbaum-Sharkovskii-Magnitskii theory of dynamical chaos in nonlinear differential equations is applicable also for nonlinear partial differential equations of diffusion type. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
70.
Nikolai Neumaier 《Communications in Mathematical Physics》2002,230(2):271-288
In this paper we explicitly construct local ν-Euler derivations , where the ξα are local, conformally symplectic vector fields and the are formal series of locally defined differential operators, for Fedosov star products on a symplectic manifold (M,ω) by means of which we are able to compute Deligne's characteristic class of these star products. We show that this class
is given by , where is a formal series of closed two-forms on M the cohomology class of which coincides with the one introduced by Fedosov to classify his star products. Moreover, we consider
star products that have additional algebraic structures and compute the effect of these structures on the corresponding characteristic
classes of these star products. Specifying the constituents of Fedosov's construction we obtain star products with these special
properties. Finally, we investigate equivalence transformations between such special star products and prove existence of
equivalence transformations being compatible with the considered algebraic structures.
Dedicated to the memory of Moshé Flato
Received: 28 June 1999 / Accepted: 11 April 2002?Published online: 11 September 2002 相似文献