Abstract: Disclosed is a soft-start circuit for power-up, which includes a reference value generation circuit, a protection threshold generation circuit and a control circuit. The reference value generation circuit outputs a reference value, which increases slowly, during a start-up process for power-up. The protection threshold generation circuit outputs a protection threshold, which increases slowly, during the start-up process for power-up. The control circuit controls an output voltage to increase slowly along with the reference value based on the reference value, during the start-up process for power-up, and to limit an output current based on the protection threshold to limit the output voltage, during the start-up process for power-up. In this way, even if the output current must operate at the peak current, a smoother current output is realized, and operation at the maximum peak current for a long-time during start-up is not allowed.

Abstract: The present invention discloses a heat exchanger and a heat exchange method, which can recover heat from a high-temperature fluid during transport. The heat exchanger includes a closed heat exchange region and a heat-receiving fluid coil mounted therein. The heat exchange method is to pass the high-temperature fluid through a heat exchange base plate in contact therewith so as to transfer heat to the heat-receiving fluid. According to the design of the heat exchanger in the present invention, modification of the original transport pipeline and mounting of a new apparatus are very convenient, the heat exchange area can be increased while saving the cost, and the heat exchange efficiency is improved.

Abstract: The present invention provides a crane boom with multi main chord consisting of an underpart boom sections, an insert jib section and a boom head connected in turn. Said underpart boom sections and insert jib section are multi-main-chord boom sections, there is a main-chord on each of the angle part of the cross-section of the multi-main-chord boom section. Said main-chords are connected one another by several belly bars. Add at least one main-chord on the angle part of the cross section along the width or the height of said multi-main-chord boom, and the added main-chord parallels to the original main-chord. The crane boom with multi main chord of the present invention, without changing the size of the boom sections during transporting, the cross-sectional area of the main-chord is increased and the integral stiffness of the boom is strengthened by increasing main-chord number of boom, thus fold increasing the structural carrying capacity of the boom which is suitable for large crane.