Subsurface penetration

A collaborative test programme covering low-alloy and high-alloy steels was carried out by the Central Electricity Generating Board and various steelmakers. Samples were exposed in specially constructed chambers held at 566°C, 593°C and 621 °C fed with power-station steam at a pressure of 3-45 MN/m for times of up to 16 286 h. In the assessment of the results both metal lost from the surface and subsurface penetration were measured. The results have been reported by King, Robinson, Howarth and Perry in a C.E.G.B. report. Selected data are shown in Fig. 7.32, in which the broken lines have been obtained by extrapolation of the experimental results. 

Todorov et al. [73] made equivalent assumptions in the modeling of a-CN.v film growth within another context. They focused their attention on the calculation of the collision cascade details following subsurface penetration of and N+ ions... 

Consistent with the definition of terms adopted for the discussion in this series of papers of integral phases of the residue studies being conducted by the Division of Entomology, University of California Citrus Experiment Station (2, 13-15), the following distinctions are noted Residues may be specified as pretreatment, posttreatment, harvest, or ultimate. The latter refers to the residue on or in foodstuffs, whether fresh or processed, at the time of consumption (2, 13). The location of residues with reference to fruit parts may be extra-surface (external to the cuticle) or subsurface. Subsurface residues may be differentiated with reference to actual location as cuticular residues or specified intracarp residues. Residues in the cuticular layers or in any of the cellular structures or matrices are herein indicated as subsurface (penetrated) residues (2, 13). 

Studies with parathion-treated citrus fruits have also shown no parathion to be present in the endocarpal, or pulp segment, portions of the fruit (Tables III, IV, and VI). Since the magenta color reaction for parathion is extremely sensitive, it is believed that even trace quantities are not present in the pulp. The rapidity of the subsurface penetration of parathion into the peel of citrus fruits and the persistence of these residues in the peel is demonstrated in Tables III through VII. 

In this section, we discuss atomistic modeling studies of the interaction of model passivated surfaces with halide ions. First, the study using conventional DFT of chloride adsorption and subsurface penetration on defect-free hydroxylated nickel oxide surfaces characteristic of passivated nickel surfaces is presented. Then the implications of using DFT-l-U are discussed as well as the interaction with other halides. This is followed hy one example on the effect of implementing surface defects characteristic of those observed experimentally on a passivated nickel surface. Finally, the application of reactive MD modeling to more complex systems including a substrate metal (copper) covered by a passive film (copper oxide) in interaction with a chloride-containing aqueous solution is presented. 

The Jurassic Smackover formation does not outcrop and is only encountered in subsurface penetrations located in the U.S. Gulf Coast area. 

Table 5-3. Comparison of the recommended maximum temperatures based on scaling and on scaling plus subsurface penetration during continuous service. The latter temperatures result in 10 mils (0.254 mm) of penetration after one year of exposure to air (John, 1996).

Alloy T max based on scaling ( C) r,nax based on scaling plus subsurface penetration (°C)... 

Probing, driving a rod or pipe into the soil and measuring the penetration resistance, obtains initial subsurface information. This is a low-cost method, but in general it is likely to supply inadequate information about subsurface conditions, especially on the depth and nature of bedrock. 

No loss-of-circulation problem No formation damage Very high penetration rate Low bit costs Low water requirement No mud requirement No ability to counter subsurface pore pressure problems Little ability to carry formation water from hole Hole erosion problems are possible if formations are soft Possible drill string erosion problems Downhole fires are possible if hydrocarbons are encountered (gas only) Specialized equipment necessary... 

Improved penetration rates (relative to mud drilling) Ability to counter high subsurface pore pressure problems ... 

Scanning acoustic microscopy (SAM) is a relatively new technique which broke through in the mid-seventies and was commercialized recently. The SAM uses sound to create visual images of variations in the mechanical properties of samples. The ability of acoustic waves to penetrate optically opaque materials makes it possible to provide surface or subsurface stmctural images nondestmctively, which might... 

The samples of citrus peel obtained by either method may have contained trace amounts of extra-surface DDT residues as differentiated from subsurface or penetrated... 

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