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Three-dimensional finite element analysis of a novel interzygapophyseal fusion device for lower cervical spine

Wang Qi, Yuan Hong, Guo Mingming, Meng Lingzhi, Long Zuoyao, Long Yu, Yang Huifeng

Acta of Bioengineering and Biomechanics

2022

Vol. 24, no. 2

187--193

A three-dimensional finite element model of the lower cervical spine was established to evaluate the biomechanical stability and stress distribution of the new lower cervical interzygapophyseal fusion device (IZFD) developed by ourselves under different construct. The aim of this study was to provide theoretical basis for further clinical application. Methods: A normal fresh cadaveric specimen (male, 35 years old) was used to establish an intact three-dimensional finite element model of C3–C6. On this basis, the comparative finite element models of the lateral mass screw rod (LMSR) system and LMSR+IZFD were established. Only C4–C5 is fixed in the lateral mass. The range of motion (ROM) and stress distribution in the flexion,extension, lateral bending and rotation of the C4–C5 segment under the three constructs were analyzed. Results: The ROM and stress distribution of the three-dimensional finite element model under load construct were within a reasonable range, which proved the validity and reliability of the model. The ROM and stress distribution of C4–C5 segment was significantly decreased in both LMSR and LMSR+IZFD constructs than those in the intact construct. The ROM and stresss distribution were even smaller in LMSR+IZFD construct than in LMSR construct. Conclusions: The IZFD combined with LMSR system can provide satisfactory stability for the lower cervical spine, and the IZFD can further improve the fixation effect of the LMSR system.

A study of distortion correction algorithms based on aspheric fisheye lens design

Li Dan, Zhang Baolong, Zhu Jiawei, Wang Qi, Zhu Zhenwei

Optica Applicata

2020

Vol. 50, nr 4

579--592

A design method of aspheric fisheye lens has been proposed in this paper, based on the requirements of automobile surround view system. The study has designed a kind of ultra-wide-angle fisheye lens, which only consists of a spherical glass lens and three aspherical plastic lenses. The maximum diameter of imaging aperture is 15. 3 mm; the working distance behind is 2.158 mm; the total length of system is 11.44 mm; the focal length is 0.97 mm; the viewing angle is 210°, and the modulation transfer function (MTF) curve is 0.35 at 60 lp/mm. Furthermore, a kind of a distortion correction algorithm for fisheye lens has been created, which calculates the position of the ideal image point with the actual image point and the obtained distortion curve and distortion model. The algorithm can correct the distorted image taken by a fisheye lens to an image without distortion, which is suitable for the human eye. The algorithm, which is simple and effective, has been applied to the automobile surround view system. It has been verified to be accurate and reasonable, after the comparison is made between the real image taken by a fisheye lens and the corrected image.