Visibility, depth

When gas concentrations are high, burning is characterized by the presence of a tall, turbulent-diffusion, flame plume. At points where the cloud s vapor had already mixed sufficiently with air, the vertical depth of the visible burning zone is about equal to the initial, visible depth of the cloud. 

FIGURE 37.3 A farmer checks the consumption of pellet feed by shrimp (Penaeus monodon) from a feed tray at a shrimp farm in Hat Yai, Thailand. A Secchi visibility depth of approximately 30-50 cm is generally maintained by the addition of fertilizers and pellet feeds. Ponds are stirred by electrical or diesel powered paddle wheels in order to keep dissolve oxygen levels above ca. 3 mg/L. Planktonic and benthic cyanobacterial blooms are a constant threat to pond management and productivity in shrimp farming. 

Name Quantity (g) Name Quantity (g) Diameter Visible depth (m) Hard tack loess... 

Additional information can be obtained, if one calculates the smallest thickness difference Ad of sf eel - for instance the depth of a crack - which can be discerned on a radiograph whose granularity is just as high as the limiting value a, of the respective class of the standard EN 584-1. For this estimation the well known relation for the (optical) density difference AD (visible contrast) which results from a difference of thickness Ad in steel is used ... 

The experimental investigations are carried out in order to get an idea about the variations of the visibility of the indications during practical inspections. The specimen where a test piece with spare eroded artificial defects (Width 25 pm depth d = 30, 60, 120 pm) and other specimen with natural cracks, a forged steering lever and a weld. As an example, in Fig 4 the steering lever with 2 cracks can be seen and below the dependance on the visibilty of a weak indication and a part of the bright indications on the field strenght H. 

All three techniques probe 500 A to 1 pm or so in depth for opaque materials, depending on the penetration depth of the incident light. For transparent materials, essentially bulk properties are measured by PL and Modulation Spectroscopy. All three techniques can be performed in ambient atmosphere, since visible light is used both as incident probe and signal. 

Figure 3.27 shows the depth profile of such a layer. Enrichment of Ti and A1 at the layer-substrate interface is visible. The Si signal in the layer increases with depth. It will subsequently be shown that it is not possible to determine from the depth profile alone whether there is diffusion of Si into the CrN layer. 

H = visible flame height S = 2.3 X = flame speed = wind speed d = cloud depth g = gravitational acceleration po = fuel-air mixture density pj = density of air r = stoichiometric air-fuel mass ratio a = expansion ratio for stoichiometric combustion under constant pressure (typically 8 for hydrocarbons)... 

The purity and the depth of the color of phthalocyanines arise front an isolated band (Q band) in the far-red end of the visible spectrum of light near 670 nm, with a molar absorption often exceeding 10s cm2 mol-1.77 321 A second absorption (B band), near 340 nm, extending to the blue of the visible spectrum is generally much less intense. Absorption spectra of 1,4-oc-tahcxyl-substitutcd PcNi322 and 1,4-octahexyl-substituted PcH2,323 both dissolved in chloroform, are shown below. 

Clearly, unless monomer is the intended photoinitiator, it is important to choose an initiator that absorbs in a region of the UV-visible spectrum clear from the absorptions of monomer and other components of the polymerization medium. Ideally, one should choose a monochromatic light source that, is specific for the chromophorc of the photoinitiator or photosensitizer. It is also important in many experiments that the total amount of light absorbed by the sample is small. Otherwise the rate of initiation will vary with the depth of light penetration into the sample. 

Surface features can also be revealed by etching, which permits identification of points of intersection of line dislocations with the surface, and this is valuable in determining the role of these imperfections in chemical processes [45,214] and, in particular, nucleus formation. Smaller topographical details can be rendered visible by the evaporation of a thin (<0.5 nm) film of gold onto the surface [215,216]. Heights and depths of surface features can be determined by interferometry [203—205]. Microcinematography has also been used [217] to record the progress of solid phase reactions. 

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