This essay introduces the methods how to solve the problems that the cage stops at the first stop and then was lifted quickly and directly without the second stop or it even can't release the brake at the second stop by innovating the electric control system of friction-wheel winch.

In view that large top torque and negative torque are produced when crank balance (primary balance) is adopted, we present the secondary balance of beam pumping unit.

The newly-designed energy-efficient beam pumping unit adopted the spring energy storage device to achieve the secondary balance,whose structure,principle and main features were also analyzed.

In this paper, the plane two-dimension numerical simulation is used to study the scour in a river whose bed is mostly cracked bedrock at the lower reaches of a spillway.

The plane two-dimension numerical simulation is used to study the simulation and calculation of the scour in a river whose bed is mostly cracked bedrock at the lower reaches of a spillway.

Based on curvilinear grids,plane two-dimension flow mo.

The Structure and Characteristic of Commonly Used 2-finger-parallel Grippers;