Structure zone models

The structure of a CVD material can be classified into three major types which are shown schematically in Fig. 2.13. In Zone (A), the structure consists of columnar grains which are capped by a domelike top. In Zone (B), the structure is also columnar but more faceted and angular. In Zone (C), it consists of fine accost grains. Examples of these structures are shown in Fig. 2.14. " This is the CVD equivalent of the structural model for vacuum-evaporated films first introduced by Movchan and Demshishin.P l... 

Regarding the development of a structural model of the refinery subsurface, it was observed that the discontinuities present in the area can be grouped into three distinct systems. With the exception of stratification (primary discontinuity), all three of these systems are represented by joints (fractures where the two opposing faces do not shift with respect to one another), shear joints (where the two faces do shift with respect to one another) and faults (fault planes or zones, marked by cataclasis, rubble and mylonite with clear evidence of shifting of the two faces). 

Field models estimate the fire environment in a space by numerically solving the conservation equations (i.e., momentum, mass, energy, diffusion, species, etc.) as a result of afire. This is usually accomplished by using a finite difference, finite element, or boundary element method. Such methods are not unique to fire protection they are used in aeronautics, mechanical engineering, structural mechanics, and environmental engineering. Field models divide a space into a large number of elements and solve the conservation equations within each element. The greater the number of elements, the more detailed the solution. The results are three-dimensional in nature and are very refined when compared to a zone-type model. 

A structure model was proposed for the compounds with Dj-type patterns by Bursill and Hyde. Figure 2.112 shows a reciprocal lattice plane of rutile with a [111] zone axis. The arrays of superspots for Dj and Dj patterns are parallel to the vectors g(121) and g(l 32), respectively. Those for D2 patterns... 

The microstructure and morphology of thick single-phase films have been extensively studied for a wide variety of metals, alloys, and refractory compounds. Structural models have been proposed (12,13). Three zones with different microstructure and surface morphology were described for thick (tens of micrometers) deposits of pure metal. At low temperature (< 0.3 Tm ), where Tm is the melting point (K) of the deposit metal, the surface mobility of the adatoms is reduced, and the deposit was reported to grow as tapered crystallites. The surface is not full density (Zone 1). At higher substrate temperature (0.3-0.45 Tm ), the surface mobility increases. The surface... 

It is shown that the mechanism of gas-solid noncatalytic reactions can be understood better by following the variations in pore structure of the solid during the reaction. By the investigation of the pore structures of the limestone particles at different extents of calcination, it has been shown that the mechanism of this particular system can be successfully represented by a two stage zone reaction model below 1000 °C. It has also been observed that the mechanism changes from zone reaction to unreacted core model at higher temperatures. 

In this work it is shown from the variations of pore structure that a zone reaction model similar to the one suggested by Ishida and Wen (9) can explain the mechanism of calcination reaction studied. 

These information from the pore structure data show that a simple two-stage zone reaction model can be successfully used to describe the mechanism of the calcination of this particular limestone and it is not necessary to consider much more complex models such as three-zone and particle-pellet models. 

THERMAL STRUCTURE AND MINERALOGY OF THE SUBDUCTING PLATE. 2.1 Subduction Zone Thermal Models... 

Figure 9 Examples of models proposed for the chemical structure of the terrestrial mantle, (a) Whole mantle convection with depletion of the entire mantle. Some subducted slabs pass through the transition zone to the coremantle boundary. Plumes arise from both the core-mantle boundary and the transition zone. This model is not in agreement with isotopic and chemical mass balances, (b) Two-layer mantle convection, with the depleted mantle above the 660 km transition zone and the lower mantle retaining a primitive composition, (c) Blob model mantle where regions of more primitive mantle are preserved within a variously depleted and enriched lower mantle, (d) Chemically layered mantle with lower third above the core comprising a heterogeneous mixture of enriched (mafic slabs) and more primitive mantle components, and the upper two-thirds of the mantle is depleted in incompatible elements (see text) (after Albarede and van der Hilst, 1999).

The critical elements of fault damage zones which are needed for fault seal evaluation and for input into reservoir behaviour simulation include (i) the dimensions of the damage zone (ii) the fault clustering characteristics (iii) the fault offset populations, which can control the distribution of fault rocks and juxtapositions (iv) the orientation distributions of deformation features present within damage zones and (v) the total thickness of fault-rocks. Each of these aspects are reviewed below, where the data presented are part of a large database collected from the structural analysis of -90 wells, (-25 km of core) from the North Sea area (see example in Fig. 7). The final part of this section presents a simple model which demonstrates the impact of damage zone structures on flow. 

Fig. 13. Conceptual model of a fault damage zone using a Sierpinski carpet. The fault zone structure can be considered to be characterised by a population series (i.e., the number of faults of different sizes, 1 8 64) and a dimension series (i.e., the size cascade of the faults present, 1, 1/3, 1/9).

A model for the development of the complex internal structures of fault zones has recently been proposed (Childs et al., 1996). Although this model does not increase the predictability of sub-surface fault zone structure, it demonstrates how complexity can arise from the operation of simple processes and provides a framework for consideration of the uncertainties inherent in prediction. The purpose of this paper is to describe and develop this model in terms relevant to the problems of fault seal prediction. While... 

Journal of the Electrochemical Society Figure 3. Three region structural model for Nafion A, fluorocarbon B, interfacial zone C, ionic clusters (11). 

It is also possible to include a third stage in which the secondary zone is relaxed as a function of s for each a [99]. Although this is more expensive, it is not necessarily more accurate because the transition state passage might be well modeled by an ensemble average of essentially fixed secondary-zone structures [93]. 

Deterministic permeability models. Application of the above principles to high temperature stable isotopes was pioneered by Norton and Taylor (1979) in their models of isotopic alteration of the Skaergaard layered intrusion and its host rocks. They used discreet zones and layers to which they assigned individual permeability values. Cartwright (1997) presented two-dimensional cases in which he modeled individual high permeability networks (fractures). Cook et al. (1997) used multiple, constant permeability zones to model the distribution of lithologies in the Alta stock area (see detailed discussion below). The advantage of this approach is that the calculated stable isotope patterns can be compared directly with measured patterns provided the permeability structure is adequately known. Permeability is also a function of time. Bolton et al. 

Fig. 17a, b. (a) Structure model and unit cell of (2xl)p2mg CO layer on a fee (110) surface (b) corresponding 2D Brillouin zone. 

Figure 6.56 gives an impression of the work related to this type of structured modeling, showing the balances and auxiliary correlations for Sq, P/V, Fp, and qQ, which are used to calculate the total oxygen transfer capacity of the reactor (OTR) as combined from mixed zone and bubble zone (cf. Fig. 4.6). 

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