The article research the relation about the towing speed and the overhanging depth of the towing cable based on the relation about the towing speed and the towing power,the towing power and the overhanging depth of the towing cable.

A new criterium based on the ratio of local spray dragging force to local smoke buoyancy was proposed to analyze the stability of smoke under sprinkler spray.

The orientation the bow of gold dredger must face to when taking up berth in flood season and the method to estimate the dragging force of gold dredger produced by the pounding of flood water are explained and introduced in this paper.

Discussion on the problem of theory divorcing from practice in present electric drive teaching material of institutions of higher education;

Achieving of PWM machine tool electric drive system based on FPGA and DSP technique;

This article presents the application of IGBT-PWM regulating speed system in machine tool's electric drive.

Based on theoretical analysis,the ratio of the maximal drag force of unit area D0 to the maximal buoyancy force of unit area B0 in the spray region is proposed as a new criterion for predicting the stability of smoke layer under sprinkler spray.

After analyzing the mechanism of the sand entry of perforated well,based on the theory of linear elasticity and considering the effect of temperature-change stress and drag force of the fluid flow through porous medium,a new model for forecasting the sand production of perforated well is established.

Under the hypothesis of steady uniform flow,the depth-integrated turbulence time-averaged momentum equation for the main flow direction is simplified by considering the effect of the vegetation on the flow as the drag force item as well as the secondary flows.