针对现有钻头心部破岩效率不高的情况，提出一种旋风状井底模型的新型钻头（旋切钻头）。通过研究旋切钻头的运动行为，分析钻头自转坐标系......

The purposes of the paper are threefold: 1) to show the fundamental possibility of physical simulation of non-stationary......

During the Mw9 Tohoku-Oki earthquake, gradual increases in both ionosphere total electron content (TEC) and geomagnetic ......