Barreling down, direct

When wines are barreled down directly, without blending beforehand, the wine batches may be heterogeneous. Yeasts and bacteria participate in these differences and they govern the completion of the fermentations. As a result, wine composition (residual sugar, alcohol and tannin concentrations) may be affected. The less the grapes are crushed and the fewer the pumping-over operations, the greater the difference between barrels of wine. 

Figure 7.9 Topological structures of a-amylase A. Two-dimensional representation of the secondary and domain structures of porcine pancreatic a-amylase. Alpha helices are represented as circles and (3-strands in the up-direction as squares, and in the down direction as double squares. The (a/(3)g—TIM barrel comprises domain A. Hydrogen bonds between (3-strands are shown by dashed lines. The a-helices and (3-strands are identified in the various domains by A, B and C. (Reprinted by permission ofthe authors M. Qian et al.120) Two-dimensional representation ofthe secondary and domain structures of barley malt a-amylase (AMY2-2). Alpha helices are represented as cylinders and (3-strands as arrows. The (a/(3)g—TIM barrel comprises domain A, with eight (3-strands and an equivalent of eight a-helices. The active-site is composed ofthe loops that connect the C-termini ofthe (3-strands to the N-termini ofthe peripheral a-helices. (Adapted from A. Kadziola et al.121)...

As before, the relationship between angle p and the pressure gradient in the barrel down-groove direction is obtained by a force balance on the solid bed element in the down-groove direction ... 

Simple pressure/drag flow. Here we treat an idealization of the down-channel flow in a melt extruder, in which an incompressible viscous fluid constrained between two boundaries of infinite lateral extent (2). A positive pressure gradient is applied in the X-direction, and the upper boundary surface at y - H is displaced to the right at a velocity of u(H) - U this velocity is that of the barrel relative to the screw. This simple problem was solved by a 10x3 mesh of 4-node quadrilateral elements, as shown in Figure 1. 

When devolatilization processes are conducted in screw extruders, the screw channels are only partially filled with the polymeric solution to be stripped of the volatile component (see Fig. 5) while the unoccupied portion of the screw channel serves to carry away the evaporated liquid. Because the barrel has a component of motion Vbz in the down channel direction, the solution is caused to flow from the extruder inlet to the outlet, which, in this case, is out of the plane of the paper. The crosschannel component of the barrel motion, Vtx, has two effects. First, it causes a circulation of the fluid in the nip and because of the continual... 

A visco-seal must be designed into the shank of the screw to prevent resin from flowing out of the barrel and onto the floor. These seals are relatively simple and consist of a small channel that is spiral cut into the shank and in the same direction as the main flights of the screw, as shown in Fig. 15.12. The pressure in the feed channel causes the resin to flow out of the extruder through the annular region between the shank of the screw and the barrel wall and also down the chan-... 

VR measured by the radar will at any point in space equal the actual projectile velocity Vp multiplied by the cosine of the angle 0, ie, VR = Vp cos 0. In recoilless firing experiments, it obviously is not possible tp locate the radar directly behind the gun. It, therefore, is necessary to locate the radar as close to the side of the gun as possible, considering blast effects on the equipment, to obtain good down range measurements. For accurate muzzle velocities or velocity of the projectile while in the barrel, the radar... 

Fig 15 Schematic diagram of the system used for initiation studies. The foil-fiver laminate is connected to an appropriate capacitor bank and the barrel and HE holder are clamped directly over the foil. When the foil explodes it drives the flyer down the barrel to impact the sample. The cross-sectional view shows how the flash produced by flyer impact can be viewed around the sample... 

The solids conveying zone. The task of the solids conveying zone is to move the polymer pellets or powders from the hopper to the screw channel. Once the material is in the screw channel, it is compacted and transported down the channel. The process to compact the pellets and to move them can only be accomplished if the friction at the barrel surface exceeds the friction at the screw surface. This can be visualized if one assumes the material inside the screw channel to be a nut sitting on a screw. As we rotate the screw without applying outside friction, the nut (polymer pellets) rotates with the screw without moving in the axial direction. As we apply outside forces (barrel friction), the rotational speed of the nut is less than the speed of the screw, causing it to slide in the axial direction. Virtually, the solid polymer is then "unscrewed" from the screw. To maintain a... 

Most screws of SSEs are single flighted, with Ls = Ds, referred to as square-pitched screws. The radial distance between the root of the screw and the barrel surface is the channel depth, H. The main design variable of screws is the channel depth profile that is H(z), where z is the helical, down-channel direction, namely, the direction of net flow of the material. The angle formed between the flight and the plane normal to the axis is called the helix angle, 0, which, as is evident from Fig. 6.8, is related to lead and diameter... 

The barrel surface becomes a flat plate covering the channel and moving at constant velocity of Vh at an angle 6b to the down channel direction... 

Comparing the present flow configuration to that in Example 2.5 of flow between two infinite parallel plates in relative motion, we note two important differences. First, the flow in the down-channel z direction is two-dimensional due to the stationary side walls created by the flight [i.e., vz (x, y), and the barrel surface has a velocity component in the x direction that results in a circulatory flow in the cross-channel direction. 

Perhaps the most severe assumption in the Darnell and Mol model is the isotropic stress distribution. Recalling the discussion on compaction in Section 4.5, the stress distribution in the screw channel is expected to be complex. The first attempt to account for the nonisotropic nature of the stress distribution was made by Schneider (36). By assuming a certain ratio between compressive stresses in perpendicular directions and accounting for the solid plug geometry, he obtained a more realistic stress distribution, where the pressure exerted by the solids on the flights, the root of the screw, and the barrel surface are all different and less than the down-channel pressure. The ratio between the former and the latter is of the order of 0.3-0.4. 

As mentioned earlier, the melting mechanism in screw extruders was first formulated by Tadmor (29) on the basis of the previously described visual observations pioneered by Bruce Maddock. The channel cross section and that of the solid bed are assumed to be rectangular, as in Fig. 9.26. The prediction of the solid bed width profile (SBP), that is the width of the solid bed X as a function of down-channel distance z, is the primary objective of the model, which can be experimentally verified by direct observation via the cooling experiment of the kind shown in Figs. 9.20-9.25. As shown by Zhu and Chen (40), the solid bed can also be measured dynamically during operation by equipping the extruder with a glass barrel. 

If Zi is the location of the beginning of the melting zone, then Xi = W. The SBP can be computed from Eq. 9.3-22. If conditions change in the down-channel direction (e.g., the barrel temperature), computations can be made in small, down-channel increments. 

Similar in some respects to an Exploding BridgeWire Detonator, the Exploding Foil Initiator uses a high electrical current to vaporize a foil and accelerate a dielectric flyer down a short barrel (typically about 0.2 mm long). The kinetic energy of the flyer is sufficient to initiate high density secondary explosives such as HNS directly. Invented in 1965 by John Stroud of the Lawrence Livermore National Laboratory. 

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