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Digby D. Macdonald Jie Qiu Samin Sharifi-Asl Jie Yang George R. Engelhardt Yi Xu Elmira Ghanbari Aoni Xu Alireza Saatchi Danyil Kovalov 《工业材料与腐蚀》2021,72(1-2):166-193
Pitting corrosion is a possible mode of failure of the carbon steel overpack of the Belgian supercontainer concept for the isolation of high-level nuclear waste (HLNW). However, no firm experimental data are currently available to estimate the probability of failure over the extended storage time (100,000 years). Extensive work shows that passivity breakdown results from the condensation of cation vacancies (CVs) at the metal/barrier layer (m/bl) interface, in response to the absorption of Cl− into oxygen vacancies at the surface of the barrier oxide layer. The CVs migrate across the bl to the m/bl interface where they condense, leading to the separation of the bl from the metal. The resulting blister prevents the growth of bl into the metal and dissolution results in blister rupture, marking a passivity breakdown event. Stabilization via differential aeration produces a potentially damaging, stable pit. We review our work on passivity breakdown and the nucleation of pits on P355 QL2 carbon steel in high-pH aqueous media typical of concrete pore solution, with emphasis on the mechanistic aspects. We conclude that failure of the carbon steel overpack containing the HLNW over a storage horizon of 100,000 years is improbable. 相似文献
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This paper studies the problem of pricing multi-asset American-style options in the Black–Scholes–Merton framework. The value
function of an option contract is known to satisfy a partial differential variational inequality (PDVI) when early exercise
is permitted. We develop a computational method for the valuation of multi-asset American-style options based on approximating
the PDVI by a non-linear penalized PDE with a penalty term with continuous Jacobian. We convert the non-linear PDE to a variational
(weak) form, discretize the weak formulation spatially by a Galerkin finite element method to obtain a system of ODEs, and
integrate the resulting system of ODEs in time with an adaptive variable order and variable step size solver SUNDIALS. Numerical
results demonstrate that employing a penalty term with continuous Jacobian in contrast to the penalty terms with discontinuous
Jacobians in use in the literature improves computational performance of the adaptive temporal integrator. In our framework
we are able to price American-style options with payoffs dependent on up to six assets on a PC. This is in contrast to the
existing literature on the pricing of American options by PDE methods, that has so far been limited to at most three-dimensional
problems. Our results open avenues for further applications to multi-dimensional problems, such as pricing convertible bonds
in multi-factor models, that will be explored in future work.
This research was supported by the National Science Foundation under grants DMI–0422937 and DMI–0422985. 相似文献
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O. Yordanov K. Gunzert-Marx P. Adrich T. Aumann K. Boretzky H. Emling G. Fehrenbacher F. Gutermuth H. Iwase H. Johansson K.L. Jones A. Kovalov T. Radon D. Schardt 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2005,240(4):863-870
Yields of neutrons produced by a 238U ion beam of 1 GeV/nucleon kinetic energy impinging on a thick Fe target were measured resulting in distributions differential in neutron angle (0° < n < 20°) and in kinetic energy (Tn > 50 MeV). The data serve in radiation protection planning for next-generation rare-isotope beam facilities. The experimental data are contrasted with predictions from transport codes as currently used in radiation shield design studies. 相似文献
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