Valve opening area ratio

at-the-opening (opening only) order

crack opening area

crack opening area COA

crack opening ratio

fire area opening and closing

hole opening ratio

large opening ratio

opening area

opening area of the Yangtze River to sea

opening area of window

Opening ratio

Opening Ratio of the Infiltration Well

small opening ratio

valve opening ratio

air to surface area ratio

amidships area ratio

anode-to-cathode area ratio

area ratio