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71.
Arkady Poliakovsky 《Comptes Rendus Mathematique》2005,341(2):97-102
We present two applications of a new method for proving upper bounds for singular perturbation problems involving maps of bounded variation. The two problems are of first and second order, respectively. The first is a minimization problem, related to the question of optimal lifting for BV-maps with values in , for which we prove a Γ-convergence result. The second problem involves the Aviles–Giga functional, , for which we construct upper bounds via a sequence of functions whose limit has gradient in BV. To cite this article: A. Poliakovsky, C. R. Acad. Sci. Paris, Ser. I 341 (2005). 相似文献
72.
We present a stable regime of asymmetric bound states for spiral pairs in a generic numerical model of a homogeneous excitable medium. In this regime, one spiral tip (slave) rotates around the other (master). Master-slave dynamics occur for both same-chirality and opposite-chirality spiral pairs in a range of parameters and initial conditions. We study the dependency of master-slave characteristics on the medium's excitation threshold and present a phenomenological model that accounts for the qualitative properties of master-slave dynamics. 相似文献
73.
We study the asymptotic behavior of scroll wave turbulence in large three-dimensional excitable media modeled by FitzHugh-Nagumo equations. The focus is on the type of turbulence caused by negative tension of scroll wave filaments, which is considered to be one of the mechanisms of cardiac fibrillation. We discovered that the initial increase in turbulence complexity can be followed by intermittent self-organization, when complex filament tangles are replaced by a small number of relatively stable triple filament strands. The intermittency is the result of a competition between the destabilizing effect of negative tension and mutual attraction of filaments with similar orientation. 相似文献
74.
Yu. N. Nozdrin A. V. Okomel’kov A. P. Kotkov A. N. Moiseev N. D. Grishnova 《JETP Letters》2004,80(1):23-25
The results are reported on the observation of the induced emission from CdxHg1?x Te samples optically pumped by a pulsed Nd:YAG laser at temperatures T<77 K. In the wave range λ~ 3300–3600 nm, both stimulated and spontaneous emission were observed. The experimentally measured emission spectra are analyzed. The properties of the spectra from the samples are discussed and the possible applications are considered. 相似文献
75.
N. S. Averkiev V. A. Berezovets M. P. Mikhailova K. D. Moiseev V. I. Nizhankovskii R. V. Parfeniev K. S. Romanov 《Physics of the Solid State》2004,46(11):2153-2162
Specific features of the energy spectrum of a separated type-II heterojunction in an external magnetic field are studied theoretically and experimentally. It is shown that, due to hybridization of the states of the valence band of one semiconductor and the conduction band of the other semiconductor at the heterointerface, there are level anticrossings, which produce quasigaps in the density of states in a nonzero magnetic field. The experimental results of magnetotransport studies for the GaInAsSb/p-InAs quaternary solid solutions with different doping levels are shown to agree well with the results of simulation, and specific features of the energy spectrum of separated type-II heterojunctions are established. 相似文献
76.
McKinley SG Vecchi PA Ellern A Angelici RJ 《Dalton transactions (Cambridge, England : 2003)》2004,(5):788-793
The complexes, CpRu(CO)2(BF4) and [CpFe(CO)2(eta2-2-methylpropene)][BF4], react with dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-Me2DBT) to give [CpRu(CO)2(DBT)][BF4] and [CpFe(CO)2(4,6-Me2DBT)][BF4], whose structures were established by X-ray diffraction studies. The same types of products are obtained when dibenzothiophenes react with CpRu(CO)2(BF4) and [CpFe(CO)2(THF)][BF4] that are adsorbed on the mesoporous silica SBA-15. DRIFT and XPS studies indicate that CpRu(CO)2(BF4) and [CpRu(CO)2(DBT)][BF4] are adsorbed on the SBA-15 by hydrogen-bonding of the BF4- anions to surface Si-O-H groups. CpRu(CO)2(BF4)/SBA-15 removes 99% of the DBT in a 45% toluene/55% hexanes simulated petroleum feedstock. This solid phase extractant is less successful for sterically-hindered 4,6-Me2DBT, as only 72% of it is removed. The results show that CpRu(CO)2(BF4) can be immobilized by adsorption on mesoporous silica and that it reacts with dibenzothiophenes in the adsorbed form, CpRu(CO)2(BF4)/SBA-15, in much the same way that it reacts in solution. 相似文献
77.
The nonlinear refractive index, n2, of sapphire was experimentally measured in the 550-1550-nm wavelength range by use of a picosecond Z-scan technique. It was found that in this spectral region the value of n2 decreases monotonically from approximately 3.3 x 10(-16) to approximately 2.8 x 10(-16) cm2/W. An empirical expression for the wavelength dependence of the nonlinear refractive index in the 270-1550-nm range was obtained. 相似文献
78.
Gekhman A. E. Moiseeva N. I. Minin V. V. Larin G. M. Kovalev Yu. V. Ustynyuk Yu. A. Rosniatovskii V. A. Timokhina E. N. Bozhenko K. V. Moiseev I. I. 《Kinetics and Catalysis》2003,44(1):40-53
In the Mo(VI)/H2O2/H2O system, the relaxation time (T
1) of protons in a water molecule and in a CH3 group decreases 10 to 30 times under conditions of dismutation of H2O2 with the formation of 1O2(1g). It is experimentally found that the overequilibrium concentration of triplet dioxygen cannot be the reason behind a decrease in T
1 in the 1H NMR spectra. Neither can it explain the anomalous line broadening in ESR spectra under conditions of 1O2(1g) formation in the systems V(V)/H2O2/AcOH and Mo(VI)/H2O2/H2O. Ab initio calculations showed that it is principle possible that the 3O4(3·-
g-1g) molecule exists in a snake-like form and is formed by the reaction between 3O2(3·-
g) and 1O2(1g), which is the product of H2O2 decomposition in the systems V(V)/H2O2/AcOH and Mo(IV)/H2O2/H2O. The interaction of 1O2 with the ·OOH radical is exothermic (Q = 2.30 kcal/mol) and leads to the formation of ·OOOOH. It is assumed that the paramagnetic species of type ·OOOOH or 3O4(3
A
1) that is formed in the reaction might be responsible for the spectral effects observed. 相似文献
79.