Giving a Blow

Oxford Gazette (an official university publication) and Oxford Magazine (a publication of views, non-official, by members of the University) in the years 2006-2007, give a blow-by-blow account of recent conflict. 

Design a die which will produce plastic film 0.52 mm thick at a linear velocity of 20 mm/s. The lay-flat widfli of the film is to be 450 mm and it is known that a blow-up ratio of 1.91 will give the necessary orientation in the film. Assume that there is no draw-down. 

There are two points of the cycle at which velocity decreases very rapidly from a high value to zero. To give a.familiar analogy, the van der Pol oscillator for this value of y. behaves not as a decent oscillator but rather as a pneumatic hammer, which idles for some time while the air pressure builds up, delivers a hammer blow, losing its kinetic energy, and then begins a similar half-cycle. 

Now Richard of Gloucester has used his cleverness to turn on his own kin. I know—I pray—that Louis is still free, but such hope as that gives me is a small, weak thing, and on its heels comes always fear for him. But chief of my terrors, waking and sleeping, are those for my boy Ned, who is my son in all but name. When I think of his head stooped under who knows what pain, my heart cramps my breath is stopped painfully by grief, as if I have been struck a blow in the throat. 

Chemical blowing agents (CBAs). These are solids that decompose to give a gas at the processing temperature. In addition to the demands above, the CBA must possess the following ... 

Foams are commercially produced several ways. Some polymerization processes produce their own foam. Polyurethanes, for example, are very exothermic. When they are formed, if a little water is present, CO2 will be a by-product. As the polymer forms, the CO2 will cause closed cell foam. As another example, a blowing agent can be injected into the molten polymer. The agent will later decompose, giving off a gas when the polymer is heated to melting. Epoxy resins are expanded into foams this way. 

Fordham (1966), pp 113-14 (Description of Esop s, lead plate and nail tests used for plain detonators. The first two tests measure only the end blow of detonators, while the 3rd test can give a rough indication of its side blow. These tests are more fully described in Vol 1 of Encycl, listed here as Ref 30)... 

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