Analysis of Stiffened Penstock External Pressure Stability Based on Immune Algorithm and Neural Network

Table 4

Appropriate range of  𝑏/𝑎 value in the conditions of different 𝑎.

𝑎 (mm)	With maximum 𝑃cr; corresponding 𝑏/𝑎	Appropriate range of  𝑏/𝑎
20	12.7	10–14
30	6.9	5–8
40	4.5	3.5–5.5
60	2.5	1.5–3.5
80	1.7	1.5–2.5