Ion temperature and rotation velocity measurements of carbon and boron ions using VUV spectroscopy on EAST.

A space-resolved vacuum ultraviolet spectroscopy is employed to measure impurity emission profiles (500-3200 Å) on EAST. This study successfully captures C IV (1548.20 and 1550.77 Å) lines emitted from carbon ions and derives ion temperatures using Doppler broadening and a collision model based on their intensity ratios. Both the emission intensity and ion temperature profiles are determined. However, the calculated results reveal a lower temperature of around 10-20 eV with the collision model, suggesting a potential need for further correction in subsequent calculations. Furthermore, this study explores relative rotation velocities from the Doppler shift, indicating an increase in toroidal rotation velocity with applied neutral beam injection. The measured results exhibit concordance with the charge exchange recombination spectrometer data. Furthermore, during boron powder dropping discharges on EAST, B II (1623.60, 1623.79, 1623.95, 1624.02, 1624.17, and 1624.38 Å) emission lines exhibiting a similar time behavior trend with boron powder injection are identified. Ion temperatures are measured using B II (1362.46 Å) through the Doppler broadening method. These techniques hold significant promise for future impurity analysis at the edge of EAST, providing valuable insights into the behavior of carbon and boron ions.

Three-dimensional biomechanical modeling and simulation of trephine cutting cornea for keratoplasty.

PURPOSE: Trephination is one of the basic operations of keratoplasty, and the biomechanical mechanism of the operation can be revealed based on three-dimensional modeling and simulation of trephine cutting cornea. METHODS: Based on the analysis of the physical and biomechanical characteristics of corneal trephination, a three-dimensional numerical model of corneal trephination is built, where the cornea can be simplified to two layers structure including stroma and epithelium, and the trephine cuts the cornea under the vertical motion load and the rotational motion load. A three-dimensional failure criterion of corneal material is proposed based on the yield strength theory. On this basis, trephination simulation is carried out, and the units of corneal material are removed from the model when they meet the defined failure criterion. RESULTS: Under the given parameters including the velocity, the angle and the angular velocity, the trephine force curves, include the linear cutting force and the rotary cutting force are obtained, and show the change of the forces with displacement during the process of trephination simulation. The maps of the equivalent stress show the destruction and deformation of the cornea. Then, the experiment of robotic trephination is carried out under the same parameters and the effectiveness of the simulation is evaluated. CONCLUSIONS: Based on mechanics theory and finite element method, the process of trephine cutting cornea has been reproduced, and the interaction mechanism is revealed, which lays the foundation for the development of real-time simulation and virtual system of the corneal surgery.