A Methodology of Three-Dimensional Medical Image Registration Based on Conformal Geometric Invariant

A three-dimensional multimodality medical image registration method using geometric invariant based on conformal geometric algebra (CGA) theory is put forward for responding to challenges resulting from many free degrees and computational burdens with 3D medical image registration problems. The mathematical model and calculation method of dual-vector projection invariant are established using the distribution characteristics of point cloud data and the point-to-plane distance-based measurement in CGA space. The translation operator and geometric rotation operator during registration operation are built in Clifford algebra (CA) space. The conformal geometrical algebra is used to realize the registration of 3D CT/MR-PD medical image data based on the dual vector geometric invariant. The registration experiment results indicate that the methodology proposed in this paper is of stronger commonality, less computation burden, shorter time consumption, and intuitive geometric meaning. Both subjective evaluation and objective indicators show that the methodology proposed here is of high registration accuracy and suitable for 3D medical image registration.</jats:p

Influence of a groove-structured vortex generator on the drag reduction characteristics of a multiphase pump

The oil–gas mixture pump significantly contributes to marginal oil field extraction and remote transportation of deep-sea oil. Nevertheless, during the operation of the mixture pump, it is inevitable to encounter problems like the separation of the mixed media from the hydraulic components as well as the gas phase from the liquid phase, which leads to enhancing the flow resistance of the mixed media. Therefore, this study investigates the influence of a groove-structure vortex generator on the drag reduction characteristics of a helical axial-flow gas–liquid multiphase pump under the design flow rate condition and various inlet gas content rates. The findings show that the vortex generator with diverse groove depths can prevent the separation of the mixed media from the blade suction surface effectively and minimize the flow resistance of the media in the 1/10 of the blade inlet. In particular, excellent drag reduction results were gained with a maximum drag reduction rate of 36.7% when the relative depth was 3/40. In addition, the efficiency of the mixture pump increased by a maximum of 2.1%, and the head increased by a maximum of 4.3%. The significance of this study lies in its potential to further optimize the design and performance of gas–liquid multiphase pumps. It provides new insights into the design and application of vortex generators. It offers robust support for the optimization and enhancement of gas–liquid multiphase pumps