排序方式: 共有22条查询结果,搜索用时 53 毫秒
21.
Liudvikas Pranevičius Darius Milčius Liudas Pranevičius Vaiva Širvinskaitë Jurgita Nomgaudyte Jean-Paul Rivier Claude Templier 《Central European Journal of Physics》2004,2(1):67-89
This paper presents a generalized approach to the mechanisms of oxidation, hydrogenation and nitriding of metals under ion
irradiation with reactive particles at elevated temperatures. Experimental results on the plasma oxidation of bilayered Y/Zr
films, the plasma hydrogenation of Mg films and the ion beam (1.2 keV N
2
+
) nitriding of stainless steel are presented and discussed. We make special emphasis on the analysis of surface effects and
their role in the initiation of mixing of bilayered films, the ingress of reactive species in the bulk and the restructuring
of the surface layers. It is suggested that primary processes driving reactive atoms from the surface into the bulk are surface
instabilities induced by thermal and ballistic surface atom relocations under reactive adsorption and ion irradiation, respectively.
The diffusion of adatoms and vacancies, at temperature when they become mobile, provide the means to relax the surface energy.
It is recognized that the stabilizing effect of surface adatom diffusion is significant at temperatures below 300–350°C. As
the temperature increases, the role of surface adatom diffusion decreases and processes in the bulk become dominant. The atoms
of subsurface monolayers occupy energetically favorable sites on the surface, and result in reduced surface energy. 相似文献
22.
Liudas Giraitis Piotr Kokoszka Remigijus Leipus Gilles Teyssière 《Statistical Inference for Stochastic Processes》2000,3(1-2):113-128
The paper is concerned with the estimation of the long memory parameter in a conditionally heteroskedastic model proposed by Giraitis et al. (1999b). We consider estimation methods based on the partial sums of the squared observations, which are similar in spirit to the classical R / S analysis, as well as spectral domain approximate maximum likelihood estimators. We review relevant theoretical results and present an empirical simulation study. 相似文献