Bottom production cross-section

Fig. 10. The variation of product cross sections with translational energy in the laboratory frame (upper scale) and the center-of-mass frame (lower scale) for reaction of Si with Sip4. The first feature in the SiF cross section corresponds to SiF2 neutral products, while the second feature corresponds to SiF + F neutral products. The arrow marked Ecj indicates the thermodynamic threshold for the charge-transfer process to form SiF -F Si -F F. The arrows at 6,4, 9.1, and 6.0 eV (top to bottom) show the thermodynamic thresholds for the dissociative processes that form Si+ -F F -F Sip3, SiF -F F -F SiF, and SiF+ -F F -F SiF2, respectively. Reprinted with permission from Weber and Armentrout (1988). Copyright 1988, American Institute of Physics.

CDF Collaboration, Measurement of the bottom quark production cross section using semi-leptonic decay electrons in p p collisions at =1.8 TeV. Phys. Rev. Lett. 71, 500-504 (1993)... 

Top typical saturation curve and variation of mean electron energy with applied field. Middle fraction of the electron swarm exceeding the specific energy at each field strength. Calculated assuming constant collision cross-section and Maxwell-Boltzman distribution. Bottom variation of products typical of involvement of ionic precursors (methane) and excited intermediates (ethane) with applied field strength... 

Na is likely deposited in the upper atmosphere by meteors along with other metals (Clemesha et al., 1981) and distributed by solar winds (Happer et al., 1994). This atomic layer is "eaten away" at its bottom by chemical reactions (e.g. molecule and aggregate formation). Fe, Al, Ca are more abundant than Na, but the D2 transition is so strong that it provides the largest product of column density CNa and transition cross section, nominally 10 — 10" atoms/cm. The layer has been studied mostly with Lidar technique (Blamont and Donahue, 1961 Albano et al., 1970 Bowman et al., 1969 Sarrazin, 2001). 

Assume that this value was determined by experimentation, and that the velocity (above) was calculated using bottom screen or distributor plate cross-sectional area. Values for process air volume in the remaining product containers are estimates based on maintaining the same face velocity. Source Equipment dimensions courtesy Glatt Air Techniques, Inc. 

The standard velocities are based upon the cross-sectional area at the bottom of the product container. This is calculated by using the following formula for calculating air velocity ... 

ASTM D 4057 (1981) describes a way to get a vertical top-to-bottom sample of petroleum products from a storage tank. A stoppered bottle is dropped vertically all the way to the bottom. Then it is unstoppered and pulled up at such a rate that the bottle is 3/4 full as it emerges from the top. Unfortunately, this is difficult even for a seasoned practitioner. Another way to sample vertically is to take samples from the top, middle, and bottom, also discussed in ASTM D 4057. A stoppered bottle is lowered to the desired depth, the stopper is pulled, the bottle is allowed to fill, and the bottle is raised. These latter samples are easier to obtain because they require little expertise. They also incur less extraction error. They do not give a full vertical cross section but give some representation of the different depths. 

The mole fractions of the feed, bottom product and the distillate determine the ratio of feed to product flow rates. In a control volume from the top of the column to any cross section b, as shown in the right hand picture in Fig. 1.56, the material balance is as follows, when the mole fraction of the volatile components in the vapour is represented by y, and the fraction in the liquid is indicated by x,... 

The mass transfer equations discussed above are now combined with a material balance on the transferred component to calculate the column or packing height required for a given separation. The column cross-sectional area A is assumed known at this point although in a complete column design A must be determined based on pressure drop considerations. The column, which is in countercurrent flow with only liquid feed and vapor product at the top, and vapor feed and liquid product at the bottom (absorber, stripper, column section), is deflned as follows ... 

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