Cooling spinning

Research at Leeds University in the UK (Dunn, 2007) that studied the pouring of liquids onto heated or cooled spinning discs and collection of them at the periphery suggested that the phenomenon could provide the food industry with more efficient and shorter mixing and processing times. It was demonstrated that mixing and... 

Thus, the polarization bias of the cooled spin is bounded by... 

As an alternative to Scheme 2, the 3B-Comp operation depicted in Scheme 3 is similar to the CNOT-CSWAP combination (Scheme 2) and cools spin C to the same degree. This gate is known as the MAJORITY gate since the resulting value of bit C indicates whether the majority of the bits had values of 0) or 1) prior to the operation of the gate. 

Example 1 Cooling spin C to the 1 purification level by PACl... 

Example 2 Cooling spin C and bypassing Shannon s entropy hound by PACl... 

RESET(rs,rc) the outcome is shown in (d). The 3-bit-compression applied in the first step operates on the three computation spins, increasing the bias of spin A by a factor of 3/2, while heating the other two spins. The 3B-Comp step cools spin A, and the following PT and RESET steps restore the initial biases of the other spins, thus the entire system is cooled. 

Reset spins may also be used for compression, thus replacing the 3B-Comp and PT steps above by a generalized RPC. The corresponding algorithm, termed PAC2, has an improved space complexity relative to PACl. We explicitly show how this is achieved. Let q be the polarization bias of the reset spin. In order to cool a single spin to ei, start with two computation spins, CB, and one reset spin. A, and perform the sequence shown in Example 4 to cool spin C. 

Example 5 Cooling spin E in EDCBA to the 2" purification level by PAC2... 

C-H bonds are spinning around tire vertical axis in tire acetate species, so tliat an almost equal probability of H emission exists in all azimutlial directions. If tlie surface is cooled to very low temperatures, tlie rotation of tlie -... 

Extrusion Processes. Polymer solutions are converted into fibers by extmsion. The dry-extmsion process, also called dry spinning, is primarily used for acetate and triacetate. In this operation, a solution of polymer in a volatile solvent is forced through a number of parallel orifices (spinneret) into a cabinet of warm air the fibers are formed by evaporation of the solvent. In wet extmsion, a polymer solution is forced through a spinneret into a Hquid that coagulates the filaments and removes the solvent. In melt extmsion, molten polymer is forced through a multihole die (pack) into air, which cools the strands into filaments. 

Flow processes iaside the spinneret are governed by shear viscosity and shear rate. PET is a non-Newtonian elastic fluid. Spinning filament tension and molecular orientation depend on polymer temperature and viscosity, spinneret capillary diameter and length, spin speed, rate of filament cooling, inertia, and air drag (69,70). These variables combine to attenuate the fiber and orient and sometimes crystallize the molecular chains (71). 

EOY speeds are the most recent development in PET spinning (78). Properties are similar to HOY and appear to be limited by the differential cooling rate from filament surface to filament core. This leads to radial distribution of viscosity, stress, and, consequentiy, molecular orientation (75). Eiber tensde strength is limited. Nevertheless, speeds up to 7000 m /min are commercial and forecasts are for speeds up to 9000 m /min by the year 2000 (79). Speeds to 9000 m/min have been studied (68,80,81). 

On the other hand, water-soluble PVA fibers are available on the market. They are stable in cool water but shrink in warm water and dissolve at 40 to 90°C. The dissolution temperature is controlled by the degree of polymerization and hydrolysis of PVA, he at-treatment conditions after spinning, etc. 

Fig. 6. Schematic of dry-jet wet spinning employing tube-in-orifice spinneret A, bore injection medium (liquid, gas, or suspended soHds) B, pump C, spinneret D, polymer spinning solution E, micrometer ( -lm) "dope" filter F, coagulation or cooling bath G, quench bath and H, collection spool.

HoUow-fiber fabrication methods can be divided into two classes (61). The most common is solution spinning, in which a 20—30% polymer solution is extmded and precipitated into a bath of a nonsolvent, generally water. Solution spinning allows fibers with the asymmetric Loeb-Soufirajan stmcture to be made. An alternative technique is melt spinning, in which a hot polymer melt is extmded from an appropriate die and is then cooled and sohdified in air or a quench tank. Melt-spun fibers are usually relatively dense and have lower fluxes than solution-spun fibers, but because the fiber can be stretched after it leaves the die, very fine fibers can be made. Melt spinning can also be used with polymers such as poly(trimethylpentene), which are not soluble in convenient solvents and are difficult to form by wet spinning. 

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