Abstract. The aim of this paper was to determine the effect of using cobalt and titanium-based alloys as implant materials for the lumbar vertebrae with an artificial intervertebral disc on the stress distribution. The lumbar vertebrae were chosen for the study because they carry considerably higher loads, especially while standing or sitting. Finite element method (FEM) simulations were conducted for three standard loads reflecting three patient's positions: recumbent, standing and sitting. The FEM analysis was performed using the SolidWorks Simulation module. Artificial units containing a pair of vertebrae with a prosthesis between them were designed by the Solid Edge software, based on micro-computed tomography CT scans of the patient's spine. The implant model was designed with its shape based on the geometry of surrounding vertebrae, consisting of an upper pad, a bottom pad and an insert (intervertebral disc). Two implant material configurations were studied. One involved the use of titanium alloy for the upper and bottom pads, while in the other, these pads were made of cobalt alloy. In both cases, a polyethylene insert was used. The FEM results demonstrate that both material configurations meet the requirements for prosthesis design. In both material configurations, the maximum stresses in each prosthesis element are almost twice higher in a sitting posture than in a recumbent position.
Dermatoscopic images are also increasingly used to train artificial neural networks for the future to provide fully automatic diagnostic systems capable of determining the type of pigmented skin lesion. Therefore, fractal analysis was used in this study to measure the irregularity of pigmented skin lesion surfaces. This paper presents selected results from individual stages of preliminary processing of the dermatoscopic image on pigmented skin lesion, in which fractal analysis was used and referred to the effectiveness of classification by fuzzy or statistical methods. Classification of the first unsupervised stage was performed using the method of analysis of scatter graphs and the fuzzy method using the Kohonen network. The results of the Kohonen network learning process with an input vector consisting of eight elements prove that neuronal activation requires a larger learning set with greater differentiation. For the same training conditions, the final results are at a higher level and can be classified as weaker. Statistics of factor analysis were proposed, allowing for the reduction in variables, and the directions of further studies were indicated.
Magnetic resonance imaging (MRI) is a widely used non-invasive imaging modality that provides a variety of high-resolution soft-tissue contrast and functional information. The development of imaging technique employing the phenomenon of nuclear magnetic resonance is focused on obtaining the best possible tissue contrast, maximisation of ratio defined by signal-to-noise-ratio (SNR) and improving the image quality. SNR can be improved by the use of contrast agents and higher-field scanners, however these are better RF coils that often provide more significant gains. Using full-wave analysis and design tools becomes especially important when the coil dimensions approach a significant fraction of a wavelength. In this paper, modelling of RF coil is presented by using special-purpose software for electromagnetic simulations. The methodology of the research assumes making numerical calculations of RF coil. The presented approach of a design of radiofrequency (RF) coils for MRI scanners using lumped circuit modelling based techniques begins to fail at high frequencies, and therefore more accurate models based on the electromagnetic field calculations must be used. This paper presents simple simulations of the electric and magnetic field in LP birdcage coil.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.