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Early version of the model

Following a rapid initial dispersion to the Kolmogorov scale, the packets continue to evolve in size and shape but at a relatively slow rate. Molecular-level mixing occurs by diffusion between packets, and the rates of diffusion and of the consequent chemical reaction can be calculated. Early versions of the model assumed spherical packets of constant and uniform size. Variants now exist that allow the packet size and shape to evolve with time. Regardless of the details, these packets are so small that they typically equilibrate with their environment in much less than a second. This is so fast compared to the usual reaction half-lives and to the mean residence time in the reactor that the vessel behaves as if it were perfectly mixed. [Pg.569]

Liquid-mass continuity equation. This equation describes the evolution of droplet diameter by evaporation. Early versions of the model took into account only of evaporation by heat transfer from the superheated vapor, but later versions took some account of direct evaporation of droplets at the wall. [Pg.1123]

Although, the ONIOM model has been employed for studies of organometal-lic systems, it has not, as far as we know, been used for studying proteins. It seems to us, however, unnecessarily complicated and provides no advantages over the hybrid potential methods discussed in section 2. In early versions of the model, there were no interactions between the different subsystems which means that the interactions between the atoms in the inner and outer regions are very poorly accounted for. In more recent versions, apparently, these interactions are included (electrostatic and Lennard-Jones) but then, of course, the model must be parametrized like the other other hybrid potentials we have mentioned. [Pg.15]

The essence of Monte-Carlo models is to calculate the path of an ion as it penetrates a crystal. Early versions of these models used the binary collision approximation, i.e., they only treated collisions with one atom at a time. Careful estimates have shown that this is an accurate procedure for collisions with a single row of atoms (Andersen and Feldman, 1970). However, when the rows are assembled into a crystal the combined potentials of many neighboring atomic rows affect ion trajectories near the center of a channel. For this reason, the more sophisticated models used currently (Barrett, 1971, 1990 Smulders and Boerma, 1987) handle collisions with far-away atoms using the continuum string approximation,... [Pg.218]

The discrepancy between the simulations of the models and experimental data from Jerusalem artichoke grown in the field is often large, in the case of early versions of the LINTUL model, for example, due to over- or underestimation of leaf area extension, ontogenetic development, and the distribution of assimilates with time (Denoroy, 1993). The models have been improved over time, however, in the light of experimental evidence. Collectively they have provided useful insights into the development physiology and biochemistry of Jerusalem artichoke. [Pg.327]

Based on these requirements, an early version of the integrator framework (cf. Subsect. 3.2.2) has been implemented [27, 251]. It was used to realize a first integrator tool between simulation models in Aspen Plus and process flow diagrams in Comos PT (cf. Subsect. 3.2.5). Innotec contributed the wrapper, connecting the framework to Comos PT, and evaluated early prototypes. The final prototypes of the framework and the integrator were limited in functionality and could not easily be adapted to integrate other documents. Nevertheless, they served as proof of concept for our integration approach. [Pg.697]

In this present version of the model the D" layer is thought to have originated very early in Earth history, as an early, incompatible element- and metal-rich basaltic crust, enriched during late accretion (4,540-4,000 Ma) with chondritic material. There is support from Nd-and Hf-isotopes for the existence of this very early differentiate of the mantle (see Sections 3.2.3.1 and 3.2.3.2). This crust, when subducted, had a bulk density which exceeded that of the mantle and numerical modeling experiments confirm that it would have stabilized at the core-mantle boundary (Davies, 2006). [Pg.125]

The next step in the calculation is to determine the actual quality in the region beyond the bubble detachment. There have been a number of attempts to predict this from mechanistic models in which the rates of evaporation near the wall and condensation in the core of the flow are estimated and the quality is evaluated surveys of early versions of such models are given by Mayinger [240] and Lahey and Moody [241]. A more recent example of such an approach is that of Zeitoun and Shoukri [242], A simpler class of methods uses a profile fit these methods are exemplified by that of Levy [243], who relates the actual quality xa to the local equilibrium quality x (calculated from Eq. 15.208) and x(Zd) (calculated from Eq. 15.213 or 15.214) as follows ... [Pg.1082]

Marty Feinberg read an early version of the notes, and provided detailed feedback on many issues including reaction rates and presenting computational material. Yannis Kevrekidis used a preliminary version of the notes as part of a graduate reactor modeling course at Princeton. His feedback and encouragement are very much appreciated, John Falconer also provided many helpful comments. [Pg.322]

In its early version (Meyer Stryer, 1988), this model did not account for the increase in the mean level of cytosolic Ca with the external stimulus nor for the relationship between the level of the stimulus and the time needed to reach the first Ca spike, which time interval is known as latency. These shortcomings are obviated in a subsequent version of the model (Meyer Stryer, 1991), which incorporates the inhibition of Ca release from the intracellular store at high levels of cytosolic Ca such a mechanism for the termination of a spike is supported by some experimental studies (Parker Ivorra, 1990 Zholos et al., 1994). A related version of that model based on a more detailed mechanism for Ca " inhibition of IP3-stimulated Ca release has been considered (Keizer De Young, 1992). [Pg.355]

A SpecTRM-RL model of TCAS was created by the author and her students Jon Reese, Mats Heim-dahl, and Holly Hildreth to assist in the certification of TCAS II. Later, as an experiment to show the feasibility of creating intent specifications, the author created the level 1 and level 2 intent specification for TCAS. Jon Reese rewrote the level 3 collision avoidance system logic from the early version of the language into SpecTRM-RL. [Pg.344]

The model was originally proposed by Paul Drude in 1902 as a simple way to describe dispersive properties of materials [108]. A quantum version of the model (including the zero-point vibrations of the oscillator) has been used in early applications to describe the dipole-dipole dispersion interactions [109-112]. A semiclassical version of the model was used more recently to describe molecular interactions [113], and electron binding [114]. The classical version has been subsequently used for ionic crystals [115-120], simple liquids [121-127], water [128-135], and ions [136-139], and in recent decades has seen widespread use in MD and MC simulations. In recent years, the Drude model was extended to interface with QM approaches in QM/MM methods [140], facilitated by the simplicity of the model in that it only includes additional charge centers. [Pg.197]

The early versions of the tube model considered a Rouse chain trapped in a spatially fixed tube having a diameter a = where is the number of the... [Pg.74]

Although the early versions of capillary models, namely, the Blake and the Blake-Kozeny models, are based on the use of V = Vq/s and = LT, it is now generally accepted [Dullien, 1992] that the Kozeny-Carman model, using Vi = VoT/e provides a more satisfactory representation of flow in beds of particles. Using equations (5.36), (5.38) and (5.40), the average shear stress and the nominal shear rate at the wall of the flow passage (equations 5.34 and... [Pg.235]

Historically, an early version of the newsvendor model was studied by Arrow et al. (1951), but the model appears to have first been stated in the form typically recognized today by Whitin (1953). [Pg.103]

The model of the inference of the best explanation is designed to give a partial account of many inductive inferences, both in science and in ordinary life. One version of the model was developed under the name abduction by Pierce [15] (early in this century and the model has been considerably developed and discussed over the last 25 years). Its governing idea is that explanatory considerations are a guide to inference that scientists infer from the available evidence to the hypothesis which would, if correct, best explain that evidence. [Pg.43]

Another recent model of interest is the risk monitor model (RMM) (Vaa, 2013). The RMM was originally referred to as simply the monitor model (Vaa et al., 2000 Vaa, 2003, 2007) and was proposed in Norwegian reports aimed at developing a model of driver behaviour (Vaa et al., 2000 Vaa, 2003). It was not until 2007 that a comprehensive account of the monitor model was published in English (Vaa, 2007), and only recently has it been renamed to become the RMM (Vaa, 2013). With the exception of the initial report, which outlined a very early draft version of the model (Vaa et al., 2000), the model s structure has remained relatively unchanged. Therefore, the version discussed here will be that of the RMM, which can be seen in Figure 4.6. [Pg.46]

The liquid-drop model was very successful in reproducing the beta-stable nuclei at a given atomic mass (A) as a function of atomic number (Z) and neutron number (AO, and the global behavior of nuclear masses and binding energies. Early versions of the liquid-drop model predicted that the nucleus would lose its stability to even small changes in nuclear shape when zVa > 39, around element 100 for beta-stable nuclei [6, 7]. At this point, the electrostatic repulsion between the protons in the nucleus overcomes the nuclear cohesive forces, the barrier to fission vanishes, and the lifetime for decay by spontaneous fission drops below lO" " s [8]. Later versions of the model revised the liquid-drop limit of the Periodic Table to Z = 104 or 105 [9]. [Pg.2]

The roots of the Muschelknautz method ( MM ) extend back to the early work performed by Professor W. Barth (see Barth (1956), for example) of the University of Karlsruhe. Over the years, as understanding of the underlying phenomena and measuring techniques developed, Muschelknautz and co-workers, and those who have now followed him, have continued to refine the model. The reader of the literature will thus encounter many versions or improvements of the MM depending on the time of publication. It will also be noted that the more recent adaptations of the basic method are rather complex. We present some elements from simpler versions of the MM in other chapters (5 and 9) in this chapter and in Appendix 6.B we present what we believe to be a rather complete account of a later version of the model. Even here, however, we are obliged to strike a balance between covering all the details of the most recent versions of the MM, which would require another book in itself to do justice to all the details, and covering only the most basic elements of the model, which would limit its applicability or utility to the reader. [Pg.111]

The SCRELA code was developed for large LOCA analyses for the SCFR, an early version of the Super FR [72, 73]. The SPRAT-DOWN, including the downward flow water rod model for the Super LWR, was extended to the SPRAT-DPWN-DP code for the large LOCA analyses [71]. The critical flow at supercritical pressure is not known. Then, the correlation at the subcritical pressure has also been used in the supercritical pressure for the LOCA analyses since the duration of supercritical pressure is very short. Both codes were verified in comparison with the REFLA-TRAC code. The SPRAT-DOWN code was applied to the small LOCAs of the Super LWR because the system pressure stays in supercritical region at the small LOCAs [71]. [Pg.48]

Only CH4 and CO oxidation cycles were considered. Calculations were made with an early version of the global, three-dimensional MOGUNTIA model [48]... [Pg.29]

Clearly, for symmetry reasons, the reverse process should also be considered. In fact, early versions of our reaction prediction and synthesis design system EROS [21] contained the reaction schemes of Figures 3-13, 3-15, and 3-16 and the reverse of the scheme shown in Figure 3-16. These four reaction schemes and their combined application include the majority of reactions observed in organic chemistry. Figure 3-17 shows a consecutive application of the reaction schemes of Figures 3-16 and 3-13 to model the oxidation of thioethers to sulfoxides. [Pg.191]

Recently a cellular automata version of the DD model has been studied [87]. The reported results are in qualitative agreement with Monte Carlo simulations [83,84]. Also, mean-field results [87] are in agreement with those early obtained in [85]. Very recently, simulations of the kinetic behavior of the DD model have been reported [88]. [Pg.421]


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