Tenth-value layer

Along the same line, the tenth-value layer (TVL) is defined by the thickness of the absorber that reduces the initial intensity of the photons by a factor of 10. It is given by... 

How many HVLs are approximately equivalent to three-tenth-value layers ... 

The information discussed above is summarized in Table I. This includes the X-ray mean energy, the X-ray emission efficiency, the tenth value layer for attenuation in water, the optimum thickness of water for maximum X-ray power utilization efficiency and the DUR at... 

Electron Energy (MeV) X-ray Mean Energy (MeV) X-ray Emission Effic. (%) Tenth Value Layer (cm) Present Work Previous Calc. Meas. Work Optimum Thickness Double Sided (g/cm2) DUR ... 

Table 4 Approximate Half Value Layers (HVL) and Tenth Value Layers (TVL) of Shielding Materials Used in Large-Scale Gamma Irradiators...

Equation 21 also can be used fora therapeutic X-ray machine ifthefactorbOOinthe numerator is changed to 60, reflecting the factoroflOhigherleakageallowedforthistypeofmachine. Tables 5.9 and 5.10, adapted fromNCRP 49, provide half- and tenth-value layers for lead and concrete for several peak voltages, and the scattered-to-incident ratio, a. 

Table 5.9 Half-Value (HVL) and Tenth-Value (TVL) Layers... 

Unfortunately, this notation can also result in more than one net with the same set of numbers. To further distinguish different nets we therefore look at the coordination sequence and wc count the number of bonded nodes up to the tenth coordination layer, the Cl 0-value, or TDIO value if it is an average over all types of nodes, see Figure 4.7. 

Estimates of the relative concentations of selected elements in fine particles collected upstream from the FGD system are listed in Table II. The values listed are some of the highest concentrations yet reported in the literature for fine coal- derived aerosols, especially those of V, Cr, and 2n, which lie in the tenth-percent range. Additional enhancements in the concentration of these elements resulting from FGD were about a factor of 2 for V, U, W, and As, a factor of 4 for Cr and Mn, and a factor of 15 for Se. If, as predicted by vapor-deposition models, the mass of there constituents resides in 0.02-ym-thick surface layers (10), then the surface concentration would be yet another 5 times greater, yielding concentrations of V, Zn, Cr, and Se in the range of 1 to 5%. 

Since both laminar and turbulent boundary layers contain laminar or viscous layers, it would seem logical that diffusion would primarily take place across these regions. If the boundary layer thickness were known, assuming a linear decrease in concentration, Eq. 10.3 could be used to estimate diffusion current. Unfortunately, the point of uniform velocity is not necessarily the point of uniform concentration. This is because particles, with their large inertia compared to air, can be carried into laminar boundary regions by mixing as well as by diffusion. The value for 8 in Eq. 10.3 will always be less than the equivalent value for the aerodynamic boundary layer thickness, in some cases being only one-tenth or even smaller (Levich, 1962). 

The flow around and therefore the heat transfer around an individual tube within the bundle is influenced by the detachment of the boundary layer and the vortices from the previous tubes. The heat transfer on a tube in the first row is roughly the same as that on a single cylinder with a fluid in crossflow, provided the transverse pitch between the tubes is not too narrow. Further downstream the heat transfer coefficient increases because the previous tubes act as turbulence generators for those which follow. From the fourth or fifth row onwards the flow pattern hardly changes and the mean heat transfer coefficient of the tubes approach a constant end value. As a result of this the mean heat transfer coefficient over all the tubes reaches for an end value independent of the row number. It is roughly constant from about the tenth row onwards. This is illustrated in Fig. 3.26, in which the ratio F of the mean heat transfer coefficient Oim(zR) up to row zR with the end value am (zR —> oo) = amoo is plotted against the row number zR. 

In another mode of presentation of experimentally determined surface charging data, values of parameters of a certain model of an electrical double layer, adjusted to the experimentally determined results, are reported rather than the PZC. Usually, this information is sufficient to calculate the PZC, and the result of such a calculation (rounded to the nearest one-tenth of pH unit) is used in the present compilation when the PZC is not explicitly reported in the original publication. A few studies report the results (usually electrokinetic potentials) for... 

The buffer factor has the consequence that the exchange coefficient fcma associated with the dissolution equilibrium between atmosphere and mixed layer must be replaced by /cma when the equilibrium is perturbed. The uptake capacity of the mixed layer is reduced to one-tenth of its equilibrium value, and the relaxation time for the transfer of excess C02 toward the deep ocean, given by Eq. (11-14) for a pulse input, is raised to r2 =220yr. This is an important result. It shows that it takes several centuries to drain from the atmosphere the excess of C02 injected by the combustion of fossil fuels. It makes little difference that combustion must be represented by a continuous source function, because any continuous function can be expressed by a time series of pulses. In the box-diffusion model of the ocean discussed by Siegenthaler and Oeschger (1978), the response to a pulse input leads to a nonexponential decay of atmospheric C02, which after equilibration with the mixed layer is somewhat faster than that in the two-box model treated here, but the time scales are still roughly the same. 

Several techniques can be used to determine the flatband potential of a semiconductor. The most straightforward method is to measure the photocurrent onset potential, ( onset- At potentials positive of (/>fb a depletion layer forms that enables the separation of photogenerated electrons and holes, so one would expect a photocurrent. However, the actual potential that needs to be applied before a photocurrent is observed is often several tenths of a volt more positive than ( fb- This can be due to recombination in the space charge layer [45], hole trapping at surface defects [46], or hole accumulation at the surface due to poor charge transfer kinetics [43]. A more reliable method for determining ( fb is electrolyte electroreflectance (EER), with which changes in the surface free electron concentration can be accurately detected [47]. The most often used method, however, is Mott- chottky analysis. Here, the 1/ Csc is plotted as a function of the applied potential and the value of the flatband... 

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