Effect of hydrogen and neutron irradiation on the failure of flawed Zircaloy-2 pressure tubes

Experiments were made with Zircaloy-2 tubes containing axial slits. Failure stress at 20 and 300 °C is increased by neutron irradiation: hydride precipitates reduce failure stress at 20 °C but not at 300 °C. There is evidence that stress applied during irradiation, and neutron dose, affect failure stress.

Crack opening displacement measurements on notched bend specimens predicted within 20% the critical crack lengths measured on full size tubes.     

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Recognition experiments with typed numerals from envelopes in the mail

Statistically weighted mask, multiple weighted mask, and n-tuple recognition methods were applied to typed numerals taken from envelopes in the mail. The experiments, all on a fairly small scale, were carried out in computer simulation. With one weighted mask per class, one practicable system achieved 0.35 per cent substitution errors with 17 per cent reject errors.