Presently, a large apparatus provided with a multi-segments rotary boom, such as a concrete pump arranged on a truck chassis or a concrete distributing boom arranged on a mobile lifting platform, is widely used in construction sites for distributing concrete from the pump truck to desired job sites. The apparatus generally comprises a pump truck chassis, a concrete pump, a pipe and a boom which is also referred to as a “distributing boom”. Concrete is alternatively fed into the transporting pipe by means of a connecting mechanism by a double feeding cylinder mounted on the truck chassis. The pipe follows the movement of the multi-segments rotary boom in a certain and constant way such that concrete may be transported to a desired job site. The boom usually comprises 2-5 segments. Referring to FIG. 1, which shows a side view of a boom of a concrete pump truck when the truck is running or the boom is in its retracted position, a first boom segment 3, a second boom segment 4, a third boom segment 5, a fourth boom segment 6 and a fifth boom segment 7 are folded together through retraction movement of the pistons of boom cylinders 2. Each segment of the boom rotates with respect to one another about pivots 9 so as to be folded and unfolded. Due to the restriction of the available space and the configuration, the rotation of these boom segments about the pivots 9 is limited within a certain range. A driving means, i.e. a boom cylinder 2, is required to drive each segment of the boom to rotate. With a movement of the piston in the boom cylinder 2, the next neighborhood segment of the boom is driven to rotate by a linkage 8. A rotating platform 1 is mounted on the truck chassis or the mobile lifting platform. When operated, the rotating platform 1 and components thereon may rotate about a vertical axis, and concrete is transported to a hose 10 located at the end of the boom through a pipe attached to the boom and then discharged from the outlet of the hose 10 to prescribed sites. Since the segments of the boom may rotate with respect to one another, the concrete transporting pipe attached thereon is also capable of rotating about pivots 9. Considerable resonance may be developed at the hose 10 attached to the end of the boom if concrete is intermittently supplied. Since such apparatus usually employs a double-piston feeding cylinder to supply concrete circularly, a pulsed impulsion is easily induced during supplying concrete such that the boom may vibrate. Such a vibration is especially disadvantageous in that it may cause a misalignment of the end of the boom as well as a cracking of the boom. If a supply frequency of the double-pistons feeding cylinder for supplying concrete is close to one half of the current natural frequency of the boom or approximate to the current natural frequency of the boom, considerable resonance, which will have an amplitude above 1000 mm under certain circumstance, may be developed in the boom. Therefore, to reduce damages and dangers caused by the resonance to the boom and the operator, the supply frequency of the pump has to be reduced such that the vibration of the end of the boom is limited within a certain range.