Dependable computing basic concepts

Avizienis A, Laprie J, RandeU B, Landwehr C. Basic concepts and taxonomy of dependable and secure computing. IEEE Transacts Dependable Secure Comput. 2004 l(l) ll-3. 

Avizienis, A., Laprie, J.C., Randell, B., Landwehr, C. Basic Concepts and Taxonomy of Dependable and Secure Computing. IEEE Trans, on Dependable and Secure Computing 1, 11-33 (2004)... 

The Avrami equationhas been extended to various crystallization models by computer simulation of the process and using a random probe to estimate the degree of overlap between adjacent crystallites. Essentially, the basic concept used was that of Evans in his use of Poisson s solution of the expansion of raindrops on the surface of a pond. Originally the model was limited to expansion of symmetrical entities, such as spheres in three dimensions, circles in two dimensions, and rods in one, for which n = 2,2, and 1, respectively. This has been verified by computer simulation of these systems. However, the method can be extended to consider other systems, more characteristic of crystallizing systems. The effect of (a) mixed nucleation, ib) volume shrinkage, (c) variable density of crystallinity without a crystallite, and (random nucleation were considered. AH these models approximated to the Avrami equation except for (c), which produced markedly fractional but different n values from 3, 2, or I. The value varied according to the time dependence chosen for the density. It was concluded that this was a powerful technique to assess viability of various models chosen to account for the observed value of the exponent, n. 

LAP 92] Lapre J.C., Avizenis A., Kopetz H. (eds), Dependability basic concepts and terminology , in Dependable Computing and Fault-Tolerant System, vol. 5, Springer, New York, 1992. 

Abstract The evaluation of key properties of materials using quantum mechanics (QM) methods is the aim of this chapter. The use of QM is necessary to calculate properties that depend on electron interactions or electron density polarization. Following the Introduction, which covers computational chemistry notions, some basic concepts concerning the Density Functional Theory (DFT) used in the presented calculations are illustrated, in addition to a brief review of intermolecular interactions. The chapter then reviews the assessment of some fundamental quantities, such as the adsorption energies of gases and hydrogen in nano-porous materials and on metallic surfaces, respectively. Finally, the calculation of hydrogen solubilization in metal alloys will be also presented. 

Depending on the nature of the class, the instructor may wish to spend more time with the basics, such as the mass balance concept, chemical equilibria, and simple transport scenarios more advanced material, such as transient well dynamics, superposition, temperature dependencies, activity coefficients, redox energetics, and Monod kinetics, can be skipped. Similarly, by omitting Chapter 4, an instructor can use the text for a water-only course. In the case of a more advanced class, the instructor is encouraged to expand on the material suggested additions include more rigorous derivation of the transport equations, discussions of chemical reaction mechanisms, introduction of quantitative models for atmospheric chemical transformations, use of computer software for more complex groundwater transport simulations, and inclusion of case studies and additional exercises. References are provided... 

Our aim in this chapter will be to establish the basic elements of those quantum mechanical methods that are most widely used in molecular modelling. We shall assume some familiarity with the elementary concepts of quantum mechanics as found in most general physical chemistry textbooks, but little else other than some basic mathematics (see Section 1.10). There are also many excellent introductory texts to quantum mechanics. In Chapter 3 we then build upon this chapter and consider more advanced concepts. Quantum mechanics does, of course, predate the first computers by many years, and it is a tribute to the pioneers in the field that so many of the methods in common use today are based upon their efforts. The early applications were restricted to atomic, diatomic or highly symmetrical systems which could be solved by hand. The development of quantum mechanical techniques that are more generally applicable and that can be implemented on a computer (thereby eliminating the need for much laborious hand calculation) means that quantum mechanics can now be used to perform calculations on molecular systems of real, practical interest. Quantum mechanics explicitly represents the electrons in a calculation, and so it is possible to derive properties that depend upon the electronic distribution and, in particular, to investigate chemical reactions in which bonds are broken and formed. These qualities, which differentiate quantum mechanics from the empirical force field methods described in Qiapter 4, will be emphasised in our discussion of typical applications. 

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