Reflective scale

Figure 28. Reflected Scaled Impulse ira Versus Angle of Incidence a.

Figure 10.6. Remote-sensed spectra of representative areas on the Moon s surface (from Gaddis et al., 1985). Left telescopic spectral reflectance scaled to unity at 1.02 i.m and offset relative to adjacent spectra right residual absorption features for the same measurements after a straight line continuum extending from 0.73 pm to 1.6 pm has been removed, (a) Highland soil sampled at the Apollo 16 landing site (b) high-Ti mare basalt at the Apollo 17 landing site (c) low-Ti mare basalt at Mare Serenitatis and (d) pyroclastic deposits at Taurus-Littrow.

Figure 10.9 Reflectance spectra obtained from Earth-based telescopes for small (< 5 km diameter) areas within the Copernicus crater on the Moon (from Pieters et al., 1985). Left reflectance scaled to unity at 1.02 im right residual absorption after continuum removal. Spectra are offset vertically, (a) Wall and (b) floor areas containing orthopyroxene are deduced to be of noritic composition (c) floor containing pyroxene and glass is an area of extensive impact melt and (d) central peak containing olivine is deduced to be troctolite.

Fig. 10, Diffuse reflectance spectra of MgO. CaO, SrO, and BaO showing exciton absorption (I, II, and III) due to the surface ions. Solids were outgassed at 1073 K, and the spectra were measured under conditions of quenched fluorescence. The reflectance scale is displaced vertically to avoid overlap of spectra. The dotted portions to the left of the vertical dashed line at n > 52,000 cm (the vacuum UV) are extrapolations (redrawn figure showing the Otc- attached to each band) [reproduced with permission from Ganone et al. (79)].

The form of Eq. (54) allows us to have better insight into the problem it reflects scaling properties of a mixture between two interfaces. The behavior of such a blend is best characterized by a set of scaling parameters defined by... 

Polarized reflectance of HMTSF-TCNQ vs. frequency from 600-25000 cm. Notice the logarithmic reflectance scale... 

Under most circumstances, it is not convenient to measure the incident and reflected beams directly with the same detector because scintillator counters have a substantially smaller dynamic range than the 105- to 1010-fold difference between the direct beam flux and reflected beam flux. Instead, direct knowledge of the detector resolution, A(20), and the conversion factor between the monitor signal and the incident beam flux, amon, can be used to estimate the absolute reflectivity. Furthermore, the absolute reflectivity is well constrained by measurements close to bulk Bragg features or at the total external reflection condition near 20 0°. These intensities are dominated by bulk properties of the substrate and provide an independent calibration on the absolute reflectivity scale. 

Drawback 1 A reflective scale is generally formed when the preheat zone is held at temperatures at or above 2300 F (1260 C). The cause of the reflective scale is the normal softening of the scale above 2320 F (1271 C) and the lower conductivity of the surface. If a furnace has this problem, reducing the preheat zone temperatures and increasing the product discharge temperature will increase furnace productivity. 

Examples of nonuniform heating-control problems above 10(X) F (538 C) are (1) nonuniform scale formation with carbon steels, (2) questionable completion of the combustion reaction (pic contact the load surface), (3) sticky scale with resultant rolled-in scale, (4) spotty decarburization of high carbon steels, (5) some stainless steels may not tolerate contact with the reducing atmosphere within the flames, and (6) using impingement heating for steel pieces of heavy cross section could cause formation of reflective scale with resultant reduction of heat transfer. 

Many believe that for greatest uniformity of temperature in top- and bottom-fired continuous furnaces, it is desirable to favor almost constant temperature from furnace end to end plus a soak zone for the ultimate heat flow rate per unit of time. This is not true if reflecting scale forms in the charge or preheat zone at temperatures above 2320 F (1270 C). Such scale will reduce heat transfer so that the product will be colder and productivity will be lower than if the charge zone had been limited to between 2250 F and 2300 F (1232 C and 1260 C). Reflecting scale develops when scale softens and becomes very smooth and the steel temperature under the scale has relatively low conductivity, preventing the steel from absorbing heat from the scale. 

With regard to color measurement, it is fair to observe that the Model 6500 was not designed as a colorimetric instrument. The optical geometry does not comply with specifications of the Commission International de L Eclairage (CIE), there is no method of setting the zero of the reflectance scale, the white standard is not specified, and, in the authors experience, it varies appreciably between instruments. Furthermore there is no provision in the software to calculate color values from the spectral data. To some extent these objections can be overcome by treating color values as though they were constituents but this yields a level of performance below the true capabilities of the instrument. This point is discussed further in the Calibration Mathematics Section. 

The polymer concentration profile has been measured by small-angle neutron scattering from polymers adsorbed onto colloidal particles [70,71] or porous media [72] and from flat surfaces with neutron reflectivity [73] and optical reflectometry [74]. The fraction of segments bound to the solid surface is nicely revealed in NMR studies [75], infrared spectroscopy [76], and electron spin resonance [77]. An example of the concentration profile obtained by inverting neutron scattering measurements appears in Fig. XI-7, showing a typical surface volume fraction of 0.25 and layer thickness of 10-15 nm. The profile decays rapidly and monotonically but does not exhibit power-law scaling [70]. 

The two exponential tenns are complex conjugates of one another, so that all structure amplitudes must be real and their phases can therefore be only zero or n. (Nearly 40% of all known structures belong to monoclinic space group Pl c. The systematic absences of (OlcO) reflections when A is odd and of (liOl) reflections when / is odd identify this space group and show tiiat it is centrosyimnetric.) Even in the absence of a definitive set of systematic absences it is still possible to infer the (probable) presence of a centre of synnnetry. A J C Wilson [21] first observed that the probability distribution of the magnitudes of the structure amplitudes would be different if the amplitudes were constrained to be real from that if they could be complex. Wilson and co-workers established a procedure by which the frequencies of suitably scaled values of F could be compared with the tlieoretical distributions for centrosymmetric and noncentrosymmetric structures. (Note that Wilson named the statistical distributions centric and acentric. These were not intended to be synonyms for centrosyimnetric and noncentrosynnnetric, but they have come to be used that way.)... 

In order to maintain a definite contact area, soHd supports for the solvent membrane can be introduced (85). Those typically consist of hydrophobic polymeric films having pore sizes between 0.02 and 1 p.m. Figure 9c illustrates a hoUow fiber membrane where the feed solution flows around the fiber, the solvent—extractant phase is supported on the fiber wall, and the strip solution flows within the fiber. Supported membranes can also be used in conventional extraction where the supported phase is continuously fed and removed. This technique is known as dispersion-free solvent extraction (86,87). The level of research interest in membrane extraction is reflected by the fact that the 1990 International Solvent Extraction Conference (20) featured over 50 papers on this area, mainly as appHed to metals extraction. Pilot-scale studies of treatment of metal waste streams by Hquid membrane extraction have been reported (88). The developments in membrane technology have been reviewed (89). Despite the research interest and potential, membranes have yet to be appHed at an industrial production scale (90). 

Measurement of Whiteness. The Ciba-Geigy Plastic White Scale is effective in the visual assessment of white effects (79), but the availabihty of this scale is limited. Most evaluations are carried out (ca 1993) by instmmental measurements, utilising the GIF chromaticity coordinates or the Hunter Uniform Color System (see Color). Spectrophotometers and colorimeters designed to measure fluorescent samples must have reversed optics, ie, the sample is illuminated by a polychromatic source and the reflected light passes through the analy2er to the detector. 

The carbide route is the preferred method of operation for most industrial gas operations. It is well suited to small-scale consumers. The high cost of acetylene in industrial gas appHcations reflects these scale, handling, and shipping factors. 

Flame Resistance. Traditionally, small-scale laboratory flammabiUty tests have been used to initially characterize foams (38). However, these do not reflect the performance of such materials in bulk form. Fire characteristics of thermal insulations for building appHcations are generally reported in the form of quaHtative or semiquantitative results from ASTM E84 or similar tunnel tests (39). Similar larger scale tests are used for aircraft and marine appHcations. 

Test specimens for burning rate data were 1.27 x 15.24 x 0.318 cm. Descriptions of burning rate and other flammabiHty characteristics developed from small-scale laboratory testing do not reflect hazards presented by these or any other materials under actual fire conditions. 

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