Through the seismic wave exploration by us in A2 and A3 working faces, the conditions, velocity, frequency and penetrating distance of seismic wave in the main mining seams are understood preliminary.

Preliminary test and study showed that phased array ultrasonic system was better in signal-to-noise ratio, more sensitive to defects, wider in testing range and higher in working efficiency...

While working in the preliminary stage, the designer will also have to consider that many of the golfers will not be able to execute the preferred shot to a particular green.