Papers by Keyword: Periodic Structures

Abstract: Generation of coupled vacancy-relief ordered structures on titanium surface induced by laser millisecond pulses irradiation was studied. To explain the geometric features of the structures the model of vacancy-deformation instability was proposed. Numerical calculation performed in accordance with the theoretical model provided good quantitative agreement with experimental results.

Abstract: With the advancement in telecommunication in indoor environment, the use of wireless technology for information systems has drastically increased. The intensive use of indoor wireless devices in 2.4GHz and 5.8GHz ISM bands causes mutual interference in neighboring networks which degrades the system performance. Secure personal communication within such wireless networks is also another important problem. A band-stop frequency selective surface (operating in the WLAN frequency band) which is attached to the walls of buildings can provide a solution for these interference and security problems. In this work, a new band-stop hybrid frequency selective surface element consisting of two circular looped type geometries is introduced which is capable of attenuating the incoming 2.4GHz and 5.8GHz ISM signals minimum 13dB for all polarizations and incident angles varies from 0⁰ to 45⁰. Besides, a periodic cell size (p=26,5mmm) which is almost one fifth of the first resonance wavelength is obtained.

Abstract: Coronary stents have been more and more widely used in clinic over the past decade. There have been a large number of stents made of different biocompatible materials available commercially in the market. It is however unclear which is more suitable to specific patients. This raises a major concern whether the choice of stents could be assessed before a delivery surgery. This paper aims to provide a computational approach for evaluating the effect of stent materials on biomechanical outcomes of the deployments of stents in different patient. It will review the typical biomaterials being used for coronary stents, seeking to qualitatively assess them for use as coronary stents. Non-linear explicit finite element (FE) procedure is carried out using the Palmaz-Schatz stent geometry to quantitatively predict the effect of mechanical properties of these biomaterials on stent and coronary artery behavior during stent deployment. A quantitative comparison is made for exploring the effect of different materials on the deployment of stents. The study is considered significant in understanding the role how stent materials affect biomechanical responses to the coronary stenting. It provides a new methodology to promote a patient-specific assessment before surgery.

Abstract: We studied several cases of dynamical problems, where the motion is driven by a concentrated force or distributed load applied at a moving position. The velocity of motion is assumed as constant. In particular, we studied interactions with periodic structure of the medium. Earlier results on one-dimensional structuresare extended to the case of an array of plates.