fire area opening and closing
opening area of the Yangtze River to sea
Opening ratio
开口率
井中压力与打开防喷器心子的操作液压比
开松比
开孔率
开洞面积
Opening Ratio of the Infiltration Well
air to surface area ratio
anode-to-cathode area ratio
area ratio between wall and window
area ratio of outside to inside crevice
Area ratio of Window to wall
area ratio of windows and wall