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991.
We experimentally test the universality of the Anderson three dimensional metal-insulator transition, using a quasiperiodic atomic kicked rotor. Nine sets of parameters controlling the microscopic details have been tested. Our observation indicates that the transition is of second order, with a critical exponent independent of the microscopic details; the average value 1.63±0.05 agrees very well with the numerically predicted value ν=1.58. 相似文献
992.
We calculate the distribution of the sextuple statistic over the hyperoctahedral group B
n
that involves the flag-excedance and flag-descent numbers “fexc” and “fdes,” the flag-major index “fmaj,” the positive and
negative fixed point numbers “
” and “
” and the negative letter number “neg.” Several specializations are considered. In particular, the joint distribution for
the pair
is explicitly derived.
相似文献
993.
Delalande M Clavaguera S Toure M Carella A Lenfant S Deresmes D Vuillaume D Simonato JP 《Chemical communications (Cambridge, England)》2011,47(21):6048-6050
An innovative sensor for the detection of nerve agents in the gas phase based on a carbon nanotube field-effect transistor was developed. A high sensitivity to organophosphorus gases was obtained by modifying gold electrodes with specific tailor-made self-assembled monolayers. 相似文献
994.
Combining diaryl-calixarenyl phosphines with [Ni(cod)(2)] resulted in highly active Kumada-Tamao-Corriu cross-coupling catalysts. With one of the ligands, TOFs up to 439,000 mol(ArBr) mol(Ni)(-1) h(-1) were observed in the reaction of 1-bromonaphthalene with PhMgBr. The systems were also found to be active at room temperature with aryl chlorides. 相似文献
995.
Bourdreux Y Lemétais A Urban D Beau JM 《Chemical communications (Cambridge, England)》2011,47(7):2146-2148
Tandem catalysis by using iron(III) chloride hexahydrate leads to carbohydrate building blocks displaying an orthogonal protecting group pattern as illustrated by the regioselective protection of trehalose and maltose disaccharides. 相似文献
996.
Alistair J. Revell Tim J. Craft Dominique R. Laurence 《Flow, Turbulence and Combustion》2011,86(1):129-151
This paper reports the application of a recently developed turbulence modelling scheme known as the C
as
model. This model was specifically developed to capture the effects of stress-strain misalignment observed in turbulent flows
with mean unsteadiness. Earlier work has reported the approach applied within a linear k-ε modelling framework, and some initial testing of it within the k-ω SST model of Menter (AIAA J 32:1598–1605, 1994). The resulting k-ε-C
as
and SST-C
as
models have been shown to result in some of the advantages of a full Reynolds Stress transport Model (RSM), whilst retaining
the computational efficiency and stability benefits of a eddy viscosity model (EVM). Here, the development of the the high-Reynolds-number
version of the C
as
model is outlined, with some example applications to steady and unsteady homogeneous shear flows. The SST-C
as
form of the model is then applied to further, more challenging cases of 2-D flow around a NACA0012 aerofoil beyond stall
and the 3-D flow around a circular cylinder in a square duct, both being flows which exhibit large, unsteady, separated flow
regions. The predictions returned by a range of other common turbulence modelling schemes are included for comparison and
the SST-C
as
scheme is shown to return generally good results, comparable in some respects to those obtainable from far more complex schemes,
for only moderate computing resource requirements. 相似文献
997.
Numerical Simulation of Coherent Structures over Plant Canopy 总被引:2,自引:0,他引:2
Konstantin Gavrilov Gilbert Accary Dominique Morvan Dmitry Lyubimov Sofiane Méradji Oleg Bessonov 《Flow, Turbulence and Combustion》2011,86(1):89-111
This paper reports large eddy simulations of the interaction between an atmospheric boundary layer and a canopy (representing
a forest cover). The problem is studied for a homogeneous configuration representing the situation encountered above a continuous
forest cover, as well as for a heterogeneous configuration representing the situation similar to an edge or a clearing in
a forest. The numerical results reproduces correctly all the main characteristics of this flow as reported in the literature:
the formation of a first generation of coherent structures aligned transversally with the wind flow direction, the reorganization
and the deformation of these vortex tubes into horse-shoe structures. The results obtained when introducing a discontinuity
in the canopy (reproducing a clearing or a fuel break in a forest), are compared with the experimental data collected in a
wind tunnel; here, the results confirm the existence of a strong turbulence activity inside the canopy at a distance equal
to 8 times the height of the canopy, referenced in the literature as the Enhance Gust Zone (EGZ) characterized by a local
peak of the skewness factor. 相似文献
998.
Stephan Dominique Andres Winfried Hochstättler Christiane Schallück 《Discrete Applied Mathematics》2011,159(16):1660-1665
We prove that the game chromatic index of n-wheels is n for n≥6. 相似文献
999.
Reaction of 4′-(3-pyridyl)-2,2′:6′,2′′-terpyridine (pyterpy) with Cu(hfacac)2 (hfacac = hexafluoroacetylacetonate) led to the formation of the novel compound [Cu3(hfacac)4(μ-pyterpy)2][Cu(hfacac)3]2 (1). The structure is composed of a trinuclear [Cu3(hfacac)4(μ-pyterpy)2]2+ cation and two [Cu(hfacac)3]− anionic species. The cation consists of a chain of three CuII atoms connected by bridging pyterpy ligands. The [Cu(hfacac)3]− anions have the hfacac ligands coordinated in their usual chelating manner through their carbonyl O donors. Besides the coulombian forces, the ionic species are fixed by C-H?O, C-H?F, F?F and a variety of unusual inter-ion C-F?π interactions that control the packing motif. These π-interactions involve the terpyridine groups from the pyterpy ligand and the five-membered rings of the chelating hexafluoroacetylacetonate anions. 相似文献
1000.
Sophie Fournier Cyril Cugnet Alain Vallat Charles H. Devillers Yoann Rousselin Marek M. Kubicki Dominique Lucas Yves Mugnier Pierre D. Harvey 《Journal of Cluster Science》2010,21(4):837-856