"advance speed" is a grammatically correct phrase and can be used in written English.
It refers to the increase in speed or rate of progress. Example: The runners were instructed to advance their speed in the last leg of the race.
The face advance speed also significantly affected wall spalling.
The relationship between spalling length, depth, ratio and the face advance speed displayed a significant range.
If the advance speed is too high, the coal spalling might increase.
But generally, the values tended to increase with the face advance speed.
However, in general, the spalling ratio reduced with the increase of face advance speed.
The spalling length and ratio presented a trend of gradual reduction with the face advance speed.
During the periodical pressure period, under different face advance speeds, the coal wall spalling ratio and depth are at different positions of the face.
Based on the finding, the nitrogen injection method and the amount of nitrogen injection were given at different face advance speeds.
During the non-periodical pressure period, under different face advance speeds, the coal wall spalling ratio and depth are at different positions of the face.
(2) During the periodical pressure period, under different face advance speeds, the coal wall spalling ratio and depth are at different positions of the face. .
Open image in new window Fig. 33 Comparison of average spalling depth at different ground pressure periods under different face advance speeds Open image in new window Fig. 34 Comparison of spalling ratio at different ground pressure periods under different face advance speeds.
