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81.
Physical processes during development of lightning flashes 总被引:3,自引:0,他引:3
Vladislav Mazur 《Comptes Rendus Physique》2002,3(10):97
The objective of this paper is to review our present understanding of the physical processes in lightning flashes during their development within or outside a cloud, following lightning initiation. This represents the ‘big picture’ of lightning development, in the scale of the cloud dimensions themselves. Since the acceptance of the bi-directional, zero-net-charge leader concept, significant changes have occurred in our understanding of the key physical processes of which a lightning flash is comprised, and in the analytical relationship between the electrical structure of a cloud and lightning parameters. These changes are discussed with an emphasis on the unifying nature of the bi-directional leader concept. To cite this article: V. Mazur, C. R. Physique 3 (2002) 1393–1409. 相似文献
82.
Diana DiBerardino Robert J. Rafac Steven Boone Vladislav P. Gerginov Carol E. Tanner 《Optics Communications》2002,210(3-6):233-243
This paper describes the position-sensitive light-collection system that we use in our fast-beam laser experiments. The collection system consists of fiber-optic bundles whose facets are arranged to accept light emitted from a beam of fluorescent atoms. The flexibility of the fiber bundles allows their use in scanning collection systems with precise position sensitivity. We describe calculations of geometrical collection efficiency using a numerical integration scheme and compare the results with measurements. We also compare the collection efficiencies of the different fiber bundle arrangements that we used as our apparatus evolved with the implementation of various improvements. 相似文献
83.
Andrey Yu. Manakov Andrey G. Ogienko Vladislav Yu. Komarov Aleksei I. Ancharov Michail A. Sheromov 《Journal of inclusion phenomena and macrocyclic chemistry》2007,58(3-4):317-320
X-ray diffraction study of quenched sample of acetone clathrate hydrate synthesized at 0.8 GPa was carried out. It was shown
that the host frameworks of the hydrate comprise uniform cavities which are similar to that of recently characterized structure
of high-pressure tetrahydrofurane hydrate. The unique peculiarity of investigated hydrate is decrease in the crystallographic
symmetry of the hydrate arising from ordering in guest subsystem. 相似文献
84.
Vladislav Čápek 《Czechoslovak Journal of Physics》1995,45(9):785-787
It is argued that memory functions from Time-Convolution Generalized Master Equations for probabilities of finding a system interacting with a genuine bath in arbitrary state of a full system of states have, under quite general conditions for asymmetric systems, zero time integrals provided that the latter exist and that no approximations were involved. 相似文献
85.
Polyesters based on 4'-hydroxyphenyl-4-hydroxybenzoate and dichlorides of dibasic acids, prepared using a high-temperature solution polycondensation in 1-chloronaphthalene, exhibit enantiotropic nematic mesomorphism. The range of temperatures for the nematic phase Δ tN can be controlled by changing the number of methylene units in the repeating polymer unit. For n = 4, Δ tN = 97°C is the largest that can be obtained. Higher n leads to smaller values of Δ tN. When n = 12, the polyester exhibits only one single C-I transition. For n > 12 a smectic mesophase can be expected in this system. Strezlecki and Liébert reported a wide range of temperatures of Δ tN (70–160°C) for the Sn polymers made by the transesterification of 4'-acetoxyphenyl-4-acetoxybenzoate and the dicarboxylic acids. We believe the latter reaction occasionally involves the internal ester linkage in the monomer unit, producing a copolyester having a random distribution of hard segment lengths and changed polymer mesomorphic properties. 相似文献
86.
87.
88.
Vladislav M. Vlasov 《Journal of Physical Organic Chemistry》2010,23(5):468-476
Changes of the activation parameters in aliphatic SN2 reactions with anionic and neutral nucleophiles in various solvents, ΔH≠ and ΔS≠, were correlated with σ constants of the substituents. The resultant δΔH≠ and δΔS≠ reaction constants are linearly related for variations of substituents at the substrate, leaving group and nucleophile. Correlations of δΔH≠ versus δΔS≠ allow the estimation of the contribution of changes of the internal enthalpy, δΔH, to the enthalpy reaction constant, δΔH≠, which gives a single linear dependence on the Hammett ρ reaction constants. The deviations from the dependence of δΔH versus ρ can be interpreted in terms of changes in the transition state structure in SN2 reactions. The results obtained show that the substituent effects on the charge development in the transition state are governed by the magnitude of δΔH. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
89.
Explicit solutions of generalized Cauchy-Riemann systems using the transplant operator 总被引:1,自引:0,他引:1
Vladislav V. Kravchenko 《Journal of Mathematical Analysis and Applications》2010,370(1):242-427
In Kravchenko (2008) [8] it was shown that the tool introduced there and called the transplant operator transforms solutions of one Vekua equation into solutions of another Vekua equation, related to the first via a Schrödinger equation. In this paper we prove a fundamental property of this operator: it preserves the order of zeros and poles of generalized analytic functions and transforms formal powers of the first Vekua equation into formal powers of the same order for the second Vekua equation. This property allows us to obtain positive formal powers and a generating sequence of a “complicated” Vekua equation from positive formal powers and a generating sequence of a “simpler” Vekua equation. Similar results are obtained regarding the construction of Cauchy kernels. Elliptic and hyperbolic pseudoanalytic function theories are considered and examples are given to illustrate the procedure. 相似文献
90.
In this paper, we propose an original approach to the solution of Fredholm equations of the second kind. We interpret the standard Von Neumann expansion of the solution as an expectation with respect to a probability distribution defined on a union of subspaces of variable dimension. Based on this representation, it is possible to use trans-dimensional Markov chain Monte Carlo (MCMC) methods such as Reversible Jump MCMC to approximate the solution numerically. This can be an attractive alternative to standard Sequential Importance Sampling (SIS) methods routinely used in this context. To motivate our approach, we sketch an application to value function estimation for a Markov decision process. Two computational examples are also provided. 相似文献