排序方式: 共有35条查询结果,搜索用时 250 毫秒
1.
Peter L. Simon Stephen K. Scott Serafim Kalliadasis John H. Merkin 《Journal of mathematical chemistry》2004,35(4):309-328
The stability of a premixed laminar flame supported by a general combustion reaction system is considered using the Evans function method. The spectrum of the linearised second-order differential operator is investigated in detail. The special structure of the differential equations due to an Arrhenius temperature dependence is exploited. It is shown that, for certain combustion systems, the limit of the Jacobian of the reaction terms as the travelling wave coordinate approaches the front and rear of the flame is a lower triangular matrix. For this type of system a simple geometrical method is shown for the study of the essential spectrum of the linearised operator, and for determining the domain of the Evans function. The results are applied to some representative combustion reactions. 相似文献
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Peter L. Simon Serafim Kalliadasis John H. Merkin Stephen K. Scott 《Journal of mathematical chemistry》2002,31(3):313-332
The steady propagation of a planar laminar premixed flame, with a one-step exothermic reaction and linear heat loss, is studied. The corresponding travelling wave equations are solved numerically. The dependence of the flame velocity on the heat loss parameter is determined and compared with known results obtained by asymptotic expansion and other approximations. Due to the introduction of an ignition temperature the problem can be reduced to a bounded interval (of length L) and the graph of flame speed versus heat loss parameter can be parametrised by L. The numerical method is tested in the case of a step function nonlinearity when the exact solution of the differential equations can also be calculated. 相似文献
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S. Kalliadasis 《The European physical journal. Special topics》2011,197(1):279-280
Comments are provided for [4]. 相似文献
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The problem of chemical reaction-diffusion wave propagation through a random, heterogeneous medium is considered using a model based on cubic autocatalysis with decay. The autocatalyst is taken to diffuse and react through a reactant loaded at constant initial concentration in a reaction domain except that there may be gaps of arbitrary width in which the reactant concentration is zero. We first study the propagation of a permanent-form wave across a single gap and determine the critical width of the gap in terms of the kinetic parameters in the system. The numerical results are compared with an analytical estimate. Next, the critical conditions for propagation across two gaps separated by a domain are determined numerically, and this is extended to a series of three gaps. From these results, a series of "rules" is established to allow us to predict whether a wave will pass through an arbitrary random array of gaps of a given size subject to some imposed total void fraction for the material. (c) 2001 American Institute of Physics. 相似文献
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Pradas M Tseluiko D Kalliadasis S Papageorgiou DT Pavliotis GA 《Physical review letters》2011,106(6):060602
Consider the effect of pure additive noise on the long-time dynamics of the noisy Kuramoto-Sivashinsky (KS) equation close to the instability onset. When the noise acts only on the first stable mode (highly degenerate), the KS solution undergoes several state transitions, including critical on-off intermittency and stabilized states, as the noise strength increases. Similar results are obtained with the Burgers equation. Such noise-induced transitions are completely characterized through critical exponents, obtaining the same universality class for both equations, and rigorously explained using multiscale techniques. 相似文献
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A. Nold A. Malijevsky S. Kalliadasis 《The European physical journal. Special topics》2011,197(1):185-191
In this Letter we examine an effective interfacial Hamiltonian approach for wetting phenomena based on two different density
approximations in the framework of a density functional theory. The system under consideration is an attractive spherical
wall subject to adsorption by a metastable liquid. We argue that, contrary to a planar geometry, in the spherical case the
popular sharp-kink approximation leads to a considerable disagreement for the film thickness with numerical results obtained
from density functional theory. We show that the deviation originates from the inaccuracy of the predicted liquid-gas surface
tension. We further demonstrate that the prediction can be substantially improved when a soft-interface approximation is adopted,
such that the liquid-gas interface is approximated by a smooth monotonic function. 相似文献
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Catarina Serafim Maria Elaine Araruna Edvaldo Alves Júnior Margareth Diniz Cllia Hiruma-Lima Lenia Batista 《Molecules (Basel, Switzerland)》2020,25(22)
Peptic ulcers are characterized by erosions on the mucosa of the gastrointestinal tract that may reach the muscle layer. Their etiology is multifactorial and occurs when the balance between offensive and protective factors of the mucosa is disturbed. Peptic ulcers represent a global health problem, affecting millions of people worldwide and showing high rates of recurrence. Helicobacter pylori infection and the use of non-steroidal anti-inflammatory drugs (NSAIDs) are one of the most important predisposing factors for the development of peptic ulcers. Therefore, new approaches to complementary treatments are needed to prevent the development of ulcers and their recurrence. Natural products such as medicinal plants and their isolated compounds have been widely used in experimental models of peptic ulcers. Flavonoids are among the molecules of greatest interest in biological assays due to their anti-inflammatory and antioxidant properties. The present study is a literature review of flavonoids that have been reported to show peptic ulcer activity in experimental models. Studies published from January 2010 to January 2020 were selected from reference databases. This review refers to a collection of flavonoids with antiulcer activity in vivo and in vitro models. 相似文献
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A. Pereira P. M.J. Trevelyan U. Thiele S. Kalliadasis 《The European physical journal. Special topics》2009,166(1):121-125
We investigate the interaction of thin films with chemical reactions by using as a model system a horizontal film with a reactive
mixture of insoluble surfactants on its free surface. The reaction is modeled by a bistable/excitable FitzHugh-Nagumo (FHN)
prototype. The chemical reaction can destabilize the film leading to the propagation of solitary pulses on its free surface. 相似文献
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ABSTRACTWe present a numerical study of a simple density functional theory model of fluid adsorption occurring on a planar wall decorated with a narrow deep stripe of a weaker adsorbing (relatively solvophobic) material, where wall-fluid and fluid-fluid intermolecular forces are considered to be dispersive. Both the stripe and outer substrate exhibit first-order wetting transitions with the wetting temperature of the stripe lying above that of the outer material. This geometry leads to a rich phase diagram due to the interplay between the pre-wetting transition of the outer substrate and an unbending transition corresponding to the local evaporation of liquid near the stripe. Depending on the width of the stripe, the line of unbending transitions merges with the pre-wetting line inducing a two-dimensional wetting transition occurring across the substrate. In turn, this leads to the continuous pre-drying of the thick pre-wetting film as the pre-wetting line is approached from above. Interestingly we find that the merging of the unbending and pre-wetting lines occurs even for the widest stripes considered. This contrasts markedly with the scenario where the outer material has the higher wetting temperature, for which the merging of the unbending and pre-wetting lines only occurs for very narrow stripes. 相似文献