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21.
Stability and convergence of the spectral Lagrange-Galerkin method for mixed periodic/non-periodic convection-dominated diffusion problems 总被引:1,自引:0,他引:1
We present a convergence analysis of the spectral Lagrange-Galerkinmethod for mixed periodic/non-periodic convection-diffusionproblems. The scheme is unconditionally stable, independentof the diffusion coefficient, even in the case when numericalquadrature is used. The theoretical predictions are illustratedby a series of numerical experiments. For the periodic case,our results present a significant improvement on those givenby Süli & Ware (1991) SIAM J. Numer.Anal.28, 423-445). 相似文献
22.
A. F. Naves P. M. Kosaka J. R. Matos D. F. S. Petri 《Journal of Thermal Analysis and Calorimetry》2005,79(2):389-392
Summary Study of the decomposition kinetics is an important tool for the development of polymer recycling in industrial scale. In this work, parameters such as activation energy, frequency factor and reaction order, were measured under dynamic conditions. Flynn-Wall-Ozawa, Van Krevelen, Horowitz-Metzger, Coats-Redfern, Madhusudanan and Vyazovkin methods were used to determine the kinetic parameters. The analysis of the results obtained by the Coats-Redfern method shows that the thermal degradation process of LDPE and HDPE corresponds to a phase boundary controlled reaction (mechanism R2). This method shows that the reaction order values of LDPE and HDPE are about 0.7 and 0.6, respectively. 相似文献
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24.
Maria Giulia Ferretti-Alloise Andr Jacot-Guillarmod Yves-Ren Naves 《Helvetica chimica acta》1970,53(6):1339-1347
The alcohols (+)-carquejanol, (?)-neocarquejanol, (?)-isocarquejanol, and (?)-neoisocarquejanol are described, and their conformations and configurations are studied by IR., NMR. and mass spectroscopies. Isocarquejanol is a mixture of conformers approximatively 50:50 with, respectively, axial and equatorial OH. 相似文献
25.
Feifel R Gel'mukhanov F Baev A Agren H Piancastelli MN Bässler M Miron C Sorensen SL Naves De Brito A Björneholm O Karlsson L Svensson S 《Physical review letters》2002,89(10):103002
An interference quenching of the nu(")=1 vibrational line in the resonant Auger decay of N 1s-->pi(*) core-excited N2 is observed and analyzed. The intensity ratio between the nu(")=1 and nu(")=0 vibrational levels of the X2Sigma(+)(g) final state shows a surprising nonmonotonous variation as a function of frequency detuning, going through a minimum with a complete suppression of nu(")=1. We have developed a simple model which shows a linear relation between the value of the detuning frequency for this minimum and the equilibrium bond distance R(0)(c) of the core-excited state. A new way is thus established of determining the equilibrium bond distance for the core-excited state with a precision deltaR(0)(c)<10(-3) A. 相似文献
26.
Cluster emission and chemical reactions in oxygen and nitrogen ices induced by fast heavy-ion impact
Ponciano CR Martinez R Farenzena LS Iza P Homem MG Naves de Brito A Wien K da Silveira EF 《Journal of mass spectrometry : JMS》2008,43(11):1521-1530
Two ices, O2 and a mixture of O2 and N2, are bombarded by 252Cf fission fragments (FF) (approximately 65 MeV at target surface); the emitted positive and negative secondary ions are analyzed by time-of-flight mass spectrometry (TOF-SIMS). These studies shall enlighten sputtering from planetary and interstellar ices. Three temperature regions in the 28-42-K range are analyzed: (1) before N2 sublimation, in which hybrid chemical species are formed, (2) before O2 sublimation, in which the TOF mass spectrum is dominated by low-mass (O2)p cluster ions and (3) after O2 sublimation, in which (N2)p or (O2)p cluster ions are practically inexistent. In the first region, four hybrid ion series are observed: NOn-1+, N2On-2(+/-), and N4On-4(-). In the second region, two positive and negative ion series are identified: (O2)pO(+/-) and (O2)pO2(+/-). Their yield distributions are fitted by the sum of two decreasing exponentials, whose decay constants are the same for all series. It is observed that the cluster ion desorption from solid oxygen is very similar to that of other frozen gases, but its yield distribution oscillates with a three- or six-atom periodicity, suggesting O3 or 3O2 units in the cluster structure, respectively. 相似文献
27.
Let r; s≥2 be integers. Suppose that the number of blue r-cliques in a red/blue coloring of the edges of the complete graph K n is known and fixed. What is the largest possible number of red s-cliques under this assumption? The well known Kruskal-Katona theorem answers this question for r = 2 or s = 2. Using the shifting technique from extremal set theory together with some analytical arguments, we resolve this problem in general and prove that in the extremal coloring either the blue edges or the red edges form a clique. 相似文献
28.
Le Guen K Miron C Céolin D Guillemin R Leclercq N Simon M Morin P Mocellin A Björneholm O Naves de Brito A Sorensen SL 《The Journal of chemical physics》2007,127(11):114315
We have studied the ultrafast dissociation of the H2S molecule upon S 2p3/2-->6a1 inner-shell excitation by combining high-resolution resonant Auger spectroscopy and energy-selected Auger electron-ion coincidence measurements. Auger final states have been correlated to the different fragmentation pathways (S+, HS+, and H2S+ ions). As an original result, we evidence a three-step mechanism to describe the resonant production of S+: the Auger recombination in the HS* fragment is followed for the A 3Pi and c 1Pi states by the S++H fragmentation mechanism. 相似文献
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30.
The displacements of double bonds and dehydrogenation by basic catalysts are examined by analogy with the preceding studies on p-menthenes and p-menthadienes [1] with bicyclic terpenes: α- and β-pinenes, sabinene and 3-carene. 相似文献