Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences最新文献_第2页

Nanocrystalline ceria imparts better high–temperature protection 纳米晶二氧化铈提供更好的高温保护

Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences Pub Date : 2004-12-08 DOI: 10.1098/rspa.2004.1352

S. Patil, S. Kuiry, S. Seal

{"title":"Nanocrystalline ceria imparts better high–temperature protection","authors":"S. Patil, S. Kuiry, S. Seal","doi":"10.1098/rspa.2004.1352","DOIUrl":"https://doi.org/10.1098/rspa.2004.1352","url":null,"abstract":"Nanomaterials have attracted considerable interest with numerous technological developments in the last decade. Nanomaterials exhibit different physicochemical properties compared with their bulk counterparts because the diameters of the nanoparticles are less than the Bohr exciton radius. Cerium oxide based materials have been extensively studied for various technological applications. In the present study, the application of nanocrystalline cerium oxide for improvement of high–temperature–oxidation resistance of stainless steel has been studied. The role of coating of nanocrystalline cerium oxide towards improvement of high–temperature–oxidation resistance has been investigated and compared with that of the micrometre–sized cerium oxide particles. It was observed that nanocrystalline ceria improved high–temperature–oxidation resistance of AISI 304 stainless steel to a large extent compared with the micrometre–sized ceria coating. Nanocrystalline ceria coating decreased the isothermal parabolic rate constant of oxidation by more than two orders of magnitude compared with that of the bare alloy. The resistance to oxide scale spallation was also found to improve with the coating of cerium oxide nanoparticles. Secondary ion mass spectroscopy (SIMS) study of nanocrystalline ceria–coated and oxidized specimens revealed the presence of nanoceria at the outermost oxide surface, indicating a change in the oxide scale growth mechanism from outward cation diffusion to inward oxygen diffusion in the bare alloy at high temperature in dry air. The oxide scale morphology was studied using a scanning electron microscope (SEM) while a focused ion beam (FIB) technique was used to study the oxide–alloy interface. X–ray photoelectron spectroscopy (XPS) study of nanocrystalline ceria showed the presence of Ce3+ and Ce4+ oxidation states. It is proposed that the presence of the Ce3+ oxidation state in nanocrystalline ceria improves the oxidation resistance of stainless steel, and the related mechanisms are discussed.","PeriodicalId":20722,"journal":{"name":"Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2004-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74278041","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 54

Review Paper. A survey of mathematical finance 评审论文。数学金融学概览

Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences Pub Date : 2004-12-08 DOI: 10.1098/rspa.2004.1386

D. Hobson

引用次数: 13

Compositional convection in the presence of a magnetic field. I. A single interface 有磁场存在的成分对流。一、单一接口

Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences Pub Date : 2004-12-08 DOI: 10.1098/rspa.2004.1375

I. Eltayeb, E. A. Hamza, J. Jervase, E. Krishnan, D. Loper

{"title":"Compositional convection in the presence of a magnetic field. I. A single interface","authors":"I. Eltayeb, E. A. Hamza, J. Jervase, E. Krishnan, D. Loper","doi":"10.1098/rspa.2004.1375","DOIUrl":"https://doi.org/10.1098/rspa.2004.1375","url":null,"abstract":"We investigate the stability of a vertical interface separating two semi–infinite fluids with differing composition of light material and permeated by a magnetic field. Both fluids possess finite kinematic viscosity, ν, thermal diffusivity, κ, magnetic diffusivity, η, and negligible material diffusion. The stability depends on six dimensionless parameters: the Prandtl number, σ (where σ = ν/ κ), the magnetic Prandtl number, σm = ν/η, the Chandrasekhar number, Qc, the Reynolds number, Re, and the ratios, Bv, Γ of the vertical and normal components to the lateral component of field. A comprehensive study of the dependence of the stability on the parameters is made when Re is small. The presence of a horizontal magnetic field tends to reduce the growth rate of the non–magnetic modes and can also give rise to new modes of instability. The addition of a vertical component of field can completely counteract the stabilizing influence of the horizontal component. For field strengths in excess of some value dependent on σ, σm and Bv, the non–magnetic unstable mode is replaced by one of two magnetic modes, one of which is a roll aligned with the field and the other inclined to it. The helicity and α–effect of the small–scale unstable motions are also discussed.","PeriodicalId":20722,"journal":{"name":"Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2004-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83708099","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 16

Oblique scattering of plane flexural–gravity waves by heterogeneities in sea–ice 海冰非均质性对平面弯曲重力波的斜散射

Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences Pub Date : 2004-12-08 DOI: 10.1098/rspa.2004.1363

T. Williams, V. Squire

{"title":"Oblique scattering of plane flexural–gravity waves by heterogeneities in sea–ice","authors":"T. Williams, V. Squire","doi":"10.1098/rspa.2004.1363","DOIUrl":"https://doi.org/10.1098/rspa.2004.1363","url":null,"abstract":"Ocean waves propagating beneath a sea–ice sheet encounter a variety of inhomogeneities, which normally arise because of the dynamic nature of the ice veneer over large physical scales. Zones of thinner, thicker, rougher or ridged ice, changes of material property, and abrupt transitions into and from open water, for example, each have their own distinctive scattering kernel that modifies the incoming wave energy spectrum as it progresses further into the ice cover. Here we present a theoretical analysis of wave propagation beneath sea–ice, where the ice is allowed to vary spatially. Isolated irregularities such as pressure ridges, rafted regions, ice islands that have become trapped in the sea–ice, open and refrozen leads, etc., are considered, as well as groups of such features, with their peripheries either welded to the surrounding ice sheet or separated from it by a free crack. Reflection and transmission coefficients, plotted as functions of wave period or wavelength, reveal considerable fine structure, including in some cases a comb of wave frequencies at which perfect transmission occurs. The work generalizes and extends work by Squire & Dixon, Williams & Squire and Evans & Porter, which all deal with abrupt transitions, to properly allow for inhomogeneity in the ice cover. For the multiple, randomly shaped, oriented and spaced irregularities observed in a real ice sheet, good agreement is found between the full solution, a wide–spacing approximation that neglects the evanescent parts of the wave field in subsequent interactions, and a simple serial approach where interactions between features are neglected and the effect of each irregularity is computed in sequence.","PeriodicalId":20722,"journal":{"name":"Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2004-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76514042","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 50

Thermal cook–off response of confined PBX 9501 受限PBX 9501的热熄火响应

Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences Pub Date : 2004-12-08 DOI: 10.1098/rspa.2004.1348

P. Dickson, B. Asay, B. Henson, L. Smilowitz

{"title":"Thermal cook–off response of confined PBX 9501","authors":"P. Dickson, B. Asay, B. Henson, L. Smilowitz","doi":"10.1098/rspa.2004.1348","DOIUrl":"https://doi.org/10.1098/rspa.2004.1348","url":null,"abstract":"The thermal cook–off response of energetic materials (ignition resulting from direct, bulk thermal heating) is important from a safety point of view, but also challenges our understanding of these materials. Explosives are not designed to be cooked off, and, especially in the case of slow cook–off, by the time the material ignites it is substantially different, both chemically and physically, from its original state. In attempting to model such a process numerically, it has generally been assumed that combustion proceeds, from an ignition point, in a more or less planar manner, as has been observed many times in pristine energetic materials at room temperature. To investigate directly the spread of reaction following cook–off in one such energetic material (PBX 9501), small discs of PBX 9501 were heated with a confining glass or sapphire window through which the early stages of the combustion process could be observed directly by high–speed photography. The resulting combustion was found to vary with temperature of ignition, but in all cases was quite different to the laminar burn model. The results of these tests are presented, together with some possible explanations of the behaviour and discussion of the implications to modelling this response.","PeriodicalId":20722,"journal":{"name":"Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2004-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83690808","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 33

Second–order multivalued stochastic differential equations on Riemannian manifolds 黎曼流形上的二阶多值随机微分方程

Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences Pub Date : 2004-11-08 DOI: 10.1098/rspa.2004.1312

F. Bernardin, M. Schatzman, C. Lamarque

引用次数: 7

On the boundary–layer equations for power–law fluids 幂律流体边界层方程的研究

Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences Pub Date : 2004-11-08 DOI: 10.1098/rspa.2004.1349

J. Denier, P. Dabrowski

引用次数: 91

Structure of boundary blow-up for higher-order quasilinear parabolic equations 高阶拟线性抛物型方程的边界爆破结构

Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences Pub Date : 2004-11-08 DOI: 10.1098/rspa.2004.1297

V. Galaktionov, A. Shishkov

引用次数: 17

Review Paper. Characterization and stability of two–phase piecewise–homogeneous deformations 评审论文。两相分段均匀变形的表征与稳定性

Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences Pub Date : 2004-11-08 DOI: 10.1098/rspa.2004.1361

Yibin Fu, A. Freidin

{"title":"Review Paper. Characterization and stability of two–phase piecewise–homogeneous deformations","authors":"Yibin Fu, A. Freidin","doi":"10.1098/rspa.2004.1361","DOIUrl":"https://doi.org/10.1098/rspa.2004.1361","url":null,"abstract":"Many solid materials exhibit stress–induced phase transformations. Such phenomena can be modelled with the aid of the nonlinear elasticity theory with appropriate choices of the strain–energy function. It is known that if a two–phase deformation (with gradient F) in a finite elastic body is a local energy minimizer, then given any point p of the surface of discontinuity, the piecewise–homogeneous deformation corresponding to the two values F±(p) of F(p) is a global energy minimizer. Thus, instability of the latter state would imply instability of the former state. In this paper we investigate the stability properties of such piecewise–homogeneous deformations. More precisely, we are concerned with two joined half–spaces that correspond to two different phases of the same material. We first show how such a two–phase deformation can be constructed. Then the stability of the piecewise–homogeneous deformation is investigated with the aid of two test criteria. One is a kinetic stability criterion based on a quasi–static approach and on the growth/decay behaviour of the interface in the undeformed configuration when it is perturbed; the other, referred to as the energy criterion, is used to determine whether the deformation is a minimizer of the total energy with respect to perturbations of the interface in both the current and undeformed configurations. We clarify the differences between the two criteria, and provide a compact formula which can be used to establish the stability/instability of any two–phase piecewise–homogeneous deformations.","PeriodicalId":20722,"journal":{"name":"Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2004-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81767676","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 48

Buckling of a critically tapered rod: properties of some global branches of solutions 临界锥杆的屈曲:解的一些整体分支的性质

Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences Pub Date : 2004-11-08 DOI: 10.1098/rspa.2004.1355

C. Stuart, G. Vuillaume

引用次数: 12