Aspects of model creation

Traditional accident models were devised to explain losses caused by failures of physical devices (chain or tree of failure events) in relatively simple systems. They are less useful for explaining accidents in software-intensive systems and for non-technical aspects of safety such as organizational culture and human decision-making. Creation of an infrastructure based on which safety analysis can function efficiently and effectively is needed. A so called safety culture for a development company and processes associated with routine tasks there, in general, is now identified as an area of root cause of accidents and that there is the greatest... 

Some aspects of design rationale, such as the work processes during the creation of a design artifact or the dependencies between different artifact versions, are covered by the domain models presented in the previous sections. This section most notably focuses on decision rationale, a term coined by Lee and Lai referring to the evaluations of alternatives, the arguments underlying the evaluations, and the criteria used for the evaluations [808]. 

The deposition of nanoparticles is an important aspect of a nanostmctures creation on a substrate [1,2]. A better understanding of complex interaction in gas dynamic processes, heat transfer and Brownian diffusion is important for proper control of the deposition. In this paper we investigate steady-state deposition of nanoparticles from a laminar flow of a hot gas between two cold flat substrates. We will use a two-dimensional description of all processes in the model. 

Although there is little evidence for auto-catalysis in dechlorination by Fe , it is still possible that localized corrosion contributes to the remediation of contaminants in environmental applications. Various investigators have postulated that localized corrosion contributes through increased surface area (44) and creation of corrosion cell domains (49-51). The corrosion cell model works on the same principle as the electrochemical model described above (Figure 3), but invokes additional effects such as the reduction of protons as the major cathodic reaction, and the creation of an electrical double layer between the anode and cathode that permits transport due to electrical migration as well as diffusion. Although many aspects of these models are plausible, there are not yet any data that specifically support them, and a study that systematically addresses the role of localized corrosion in remediation applications of Fe remains to be done. 

Models are an excellent way to uncover aspects of physical reality. However, we cannot be too proud of our own creations, particularly of our pet hypotheses. I find this to be particularly true of modelers. After all, what else does the bedraggled theoretician have Careful pruning of any inflated claims and self-analysis coupled to good communication will greatly enhance the contribution made via this exercise. 

As fast liquid-phase chemical reactions usually occur in the diffusion area, a macrokinetic approach should be used to reveal their aspects and specificity, as it describes reactions with consideration of the heat and mass transfer [47, 48]. This approach to the modelling of fast polymerisation processes, such as the cationic polymerisation of isobutylene [27-30,38,39,49], has revealed aspects of its behaviour. Many problems of fast chemical reactions were solved via the creation of sufficiently high turbulence in a reaction zone within small-scale tubular turbulent devices. 

In parallel to the development of these security architectures, an international effort has led to the creation of Airworthiness Security Process (AWSP) document ED-202/DO-326 [10] that standardizes the development process of aircraft systems with respect to security. This document aims at providing a joint basis for the certification of information security aspects of aircraft systems. Consequently, this document focuses on security aspects that have an effect on the safety of the aircraft, these aspects are called Security for Safety . The document does not deal with other security aspects concerning, for instance, the protection of passenger privacy or the protection of aircraft manufacturer intellectual property. In this paper we restrict ourselves to the modelling and analysis of Security for Safety . 

Table 1 gives an overview of dimensions of simulation and the characteristics of different simulators with examples. The chapter will focus on training models to improve patient safety in different aspects of vascular access (VA) creation. 

That this phase transition from the dispersed to the flocculated structure of the chains is accompanied by the formation of cavities or voids between the carbon black particles was deduced from the results of the investigations of density change behavior. This aspect of the model also derives from the gas absorption experiments performed by Tanioka et al. [33] they found a sudden increase in the CO2 sorption of carbon-black-fdled compounds at the critical volume concentration. They did not, however, offer any explanation for this phenomenon. The new model, which includes explanations for the creation of the cavities during the flocculation process, can be used to explain the experimental results. 

Systemic risk can thus be defined as the potential for systemic failure. Systemic approaches have been, or are being, implemented to control complexity, particularly through the creation of global installation models designed to smdy important properties such as safety or availability. These quantitative RAMS (Reliabilty, Availability, Maintainability and Safety) models, based on probabilistic approaches, are fairly well accepted for their representation of pure hardware elements (random failures) and human factors. They are much less so for their representation of deterministic aspects of computer systems (systemic or systematic failures). 

Hence, the results stated in the present chapter give a purely practical aspect of the application of such theoretical concepts as the cluster model of the amorphous state structure of polymers and fractal analysis for the description of the structure and properties of polymers treated as natural nanocomposites. The goal-directed creation of the necessary nanostructure allows polymers to be obtained whose properties are just as good as (and even exceeding) those of composites. Structureless (defectless) polymers are the most perspective in this respect. Such polymers can be a natural replacement for a large number of polymer nanocomposites elaborated at present. 

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