Ceiling model

Research Opportunities with the Caco-2 Ceil Model... 

This more or less regular structure forms the basis of the cell model in its simplest form it is assumed that each molecule is confined to its own cell. The first attempts to give a description of the liquid state with the ceil model are due to Eyeing [1936] and Eyeing and Hirschfel-DER [1937J. However, Lennard-Jones and Devonshire [1937, 1938] were the first to iss the cell model in the interpretation of the thermodynamic properties of a liquid in terms of intermolecular forces. 

The result (18.3.4) includes what we have called collective and individual motions. Let us now consider a ceil model for hard spheres (cf. Prigogine [1954] ). Here each particle is allowed to move freely along some characteristic "free length If. According to an elementary result of quantum theory, the corresponding zero point energy is... 

Walton, W. D. and K. A. Notarianni, 1993, Comparison of Ceiling Jet Temperatures Measured in an Aircraft Hanger Test Fire with Temperatures Predicted by the DETACT-QS and LA VENT Computer Models, NIST, NISTIR 4947. 

With LES we get much more information than with traditional time-averaged turbulence models, since we are resolving most of the turbulence. In Fig. T1.15 the computed u velocity is shown as a function of time in two cells one cell is located in the wall jet (Fig.. 15a), and the other cell is in the middle of the room (Fig. ll.lSh). It is found the instantaneous fluctuations are very large. For example, in the region of the wall jet below the ceiling where the time-averaged velocity u)/l] ) is typically 0.5, the instantaneous velocity fluctuations are between 0.2 and 0.9. In the middle of the room, which is a low-velocity region, the variation of u is much slower, i.e., the frequency is lower. 

FIGURE 12.26 Velocity decay in a wall jet along the ceiling in a room and in a model. 

FIGURE 12.30 Model experiments with nonisothermal flow in three different models with ceiling heating. 

Pharmacokinetics. Figure 2 Sigmoid Emax model of pharmacodynamics with Hill coefficient (H), concentration producing half-maximum effect (CE50), threshold concentration (CE05), and ceiling concentration (CE95). 

Downward flame spread for scenario B. Once the horizontal, concurrent flame spread along the wall ceiling intersection has reached an opposite corner in the compartment the downward flame spread in the upper layer starts. In reality, this could possibly start happening during the concurrent flame spread time interval. In the current version of the model, no account is taken of the relatively low oxygen concentration in the upper layer. The flame spread is quite slow at first since the wall material has a relatively low sur-... 

Yao, X. and Marshall, A. W., Characterizing Turbulent Ceiling Jet Dynamics with Salt-Water Modeling, Fire Safety Science-Proceedings of the Eighth International Symposium, Eds. Gottuk, G. T. and Lattimer, B. Y., pp. 927-938. 

The hazard endpoint time scale th describes the length of time required for the contaminant to pose a hazard. There are many different time scales associated with various toxicity levels (e.g., TLV-C ceiling limit values are never to be exceeded, TLV-STEL values are not to be exceeded in a 15-min period, etc.). Time scales associated with flammability hazards reflect the maximum local concentration (and also typically including peak-to-mean concentration ratios) and for reasons discussed above are considered representative of dispersion model averaging times of around 20 s. 

Sally paces around your office as she gazes at various geometrical models hanging on strings from the ceiling. Why are women represented by lowly lines ... 

To be able to predict the release of SVOCs from a material to the indoor environment it is important to understand the fundamental mechanisms in order to mathematically model the emissions. The emission behavior of DEHP from PVC in the FLEC and CLIMPAQ experiments (Clausen et al., 2004) have now been successfully modeled (Xu and Little, 2006). Fluid building materials such as paints (Clausen, 1993 Xu and Little, 2006) and wood oil (Clausen, 1997) may also emit SVOCs and are usually used on large indoor surfaces such as walls, ceilings and floors. Such wet materials may be applied on substrates like wood or plaster board. The emission of for example, Texanol from water-based paint was found likely to be limited by gas phase mass transport (Clausen, 1993) similar to the DEHP emission from PVC (Clausen et al., 2004). 

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