Concentrated-user scenario

User access (concentrated, distributed). In the concentrated users scenario ( CON ), approximately 25% of the population have access to hydrogen by 2020, 50% by 2025 and 85% by 2030. In contrast, in the distributed users scenario ( DIS ), 50% of the population already have access to hydrogen by 2020, 90% by 2025, and the whole population by 2030. The scenarios do not differ in the period until 2015, when only the early-user centres are covered. 

Figure 14.6(a). Geographical allocation of hydrogen demand in Germany until 2030 concentrated users scenario . 

The roll-out strategy for hydrogen from 2015 to 2030 ( concentrated users scenario or distributed users scenario) substantially shapes the development of the hydrogen... 

The figures show the infiuence of the current number of conventional FSs in the different countries for example, Italy has a high number of small stations today, and since the hydrogen FS rollout is based on existing stations, this trend can be seen for hydrogen stations, too. Large FSs are basically only relevant in the concentrated-user scenario, where they would first be developed in densely populated areas. 

The beginning of the possible market introduction of hydrogen passenger cars in the most optimistic scenarios is around 2015, which is also in line with the implementation plan of the European Hydrogen and Fuel Cell Technology Platform (HFP, 2007). The Reference scenario features high policy support, fast learning, concentrated users, early network and no country-specific bounds. 

Referenced Calculations. Exposure assessment involves numerous calculations, covering both cross-media transfers of chemicals and the derivation of exposures from concentrations and scenario-specific parameters. In general terms, such calculations can be viewed as the limiting case (in simplicity) of either theoretical or empirical models. All calculations in Risk Assistant for deriving exposures from concentrations in an appropriate medium (e.g. inhalation exposures from air concentrations) are obtained from the Exposure Factors Handbook (4). Equations for evaluating cross-media transfer for particular exposure scenarios (e.g. volatilization from domestic water to household air) are obtained from literature sources. For such equations, the original reference is provided for the user. 

Figure 11.6 Fueling stations in the last phase (T4) - distributed- (left) and concentrated- (right) user scenarios...

The second stage realizes a two-step procedure that re-calculates the ozone concentration over the whole space S = (tp, A, z) (, A)e l 0atmospheric boundary layer (zH 70 km), whose consideration is important in estimating the state of the regional ozonosphere. These two steps correspond to the vertical and horizontal constituents of atmospheric motion. This division is made for convenience, so that the user of the expert system can choose a synoptic scenario. According to the available estimates (Karol, 2000 Kraabol et al., 2000 Meijer and Velthoven, 1997), the processes involved in vertical mixing prevail in the dynamics of ozone concentration. It is here that, due to uncertain estimates of Dz, there are serious errors in model calculations. Therefore the units CCAB, MFDO, and MPTO (see Table 4.9) provide the user with the principal possibility to choose various approximations of the vertical profile of the eddy diffusion coefficient (Dz). 

The definition of equivalent, while different in a few details, is very similar to the notion of information capacity in Sect. 2.1. One scenario that they tackle is that of view integration. The authors state that their goals are much more pragmatic than some of the existing work as previously discussed [Batini et al. 1986 Biskup and Convent 1986 Casanova and Vidal 1983], take a more theoretical approach. As such, Rosenthal and Reiner concentrate on a usable tool they only detect homonyms and synonyms, and such conflicts are presented to the user for resolution. They then perform a duplicate removing union between the two schemas. No mappings are created between the schemas. 

Screening with QUICK RISK. For users who need to set assessment priorities for a large number of sites, QUICK RISK provides a means to accomplish the task rapidly. The user need only specify probable contaminant concentrations in environmental media, and QUICK RISK applies appropriately conservative exposure assumptions. Although only one scenario is considered for any medium, further detail is probably not needed for the initial selection of site priorities, and QUICK RISK provides for consistent evaluation. Assuming that concentration estimates were available, several hundred sites could be evaluated in a single day. 

Although hoods are most commonly used to control concentrations of toxic vapors, they can also serve to dilute and exhaust flammable vapors. Although theoretically possible, it is extremely unlikely (even under most worst-case scenarios) that the concentration of flammable vapors will reach the lower explosive limit (LEL) in the exhaust duct. However, somewhere between the source and the exhaust outlet of the hood, the concentration will pass through the upper explosive limit (UEL) and the LEL before being fully diluted at the outlet. Both the hood designer and the user should recognize this hazard and eliminate possible sources of ignition within the hood and its ductwork if there is a potential for explosion. The use of duct sprinklers or other suppression methods in laboratory fume ductwork is not necessary, or desirable, in the vast majority of situations. 

Some consideration was given to the first MSDS for a laboratory chemical that students were actually ask to read in detail. One recommendation is to use an older form MSDS. These are usually shorter, are more narrative, and contain less arcane abbreviations than the American National Standards Institute (ANSI) format. The information on physical properties and precautionary labeling is usually found up front. The first MSDS should represent a chemical that has some obvious hazard already known to most of the students, such as ammonium hydroxide. The point is to introduce the MSDS as a useful document and convey some respect for the information it contains. TAs (and faculty) must be instructed not to belittle or ridicule the MSDS as a useless bureaucratic document. Students should appreciate the fact that a MSDS has to address the worst possible industrial scenario. They should be told that MSDSs for dilute solutions are often the same as those for concentrated solutions or pure chemicals. The same generic statements are often used, in particular the disclaimer that usually states something like The user should recognize that this product can cause severe injury and even death, especially if improperly handled or the known dangers are not heeded. This statement was on a MSDS for lump iron. 

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