Three‐dimensional design of a geometric model for an ocular prosthesis in ex vivo anophthalmic socket models

2020 ◽  
Author(s):  
Sébastien Ruiters ◽  
Sohaib Shujaat ◽  
Karla Faria Vasconcelos ◽  
Eman Shaheen ◽  
Reinhilde Jacobs ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Geometric Model ◽  
Three Dimensional ◽  
Ocular Prosthesis ◽  
Anophthalmic Socket

A Methodology to Analyze Changes in Lipid Core and Calcification Onto Fibrous Cap Vulnerability: The Human Atherosclerotic Carotid Bifurcation as an Illustratory Example

2009 ◽  
Vol 131 (12) ◽  
Author(s):  
Dimitrios E. Kiousis ◽  
Stephan F. Rubinigg ◽  
Martin Auer ◽  
Gerhard A. Holzapfel
Keyword(s):  
Ex Vivo ◽  
Geometric Model ◽  
Three Dimensional ◽  
Carotid Bifurcation ◽  
Vulnerability Index ◽  
Patient Specific ◽  
Lipid Core ◽  
Fibrous Cap ◽  
Treatment And Prevention ◽  
Morphological Criteria

A lipid core that occupies a high proportion of the plaque volume in addition to a thin fibrous cap is a predominant indicator of plaque vulnerability. Nowadays, noninvasive imaging modalities can identify such structural components, however, morphological criteria alone cannot reliably identify high-risk plaques. Information, such as stresses in the lesion’s components, seems to be essential. This work presents a methodology able to analyze the effect of changes in the lipid core and calcification on the wall stresses, in particular, on the fibrous cap vulnerability. Using high-resolution magnetic resonance imaging and histology of an ex vivo human atherosclerotic carotid bifurcation, a patient-specific three-dimensional geometric model, consisting of four tissue components, is generated. The adopted constitutive model accounts for the nonlinear and anisotropic tissue behavior incorporating the collagen fiber orientation by means of a novel and robust algorithm. The material parameters are identified from experimental data. A novel stress-based computational cap vulnerability index is proposed to assess quantitatively the rupture-risk of fibrous caps. Nonlinear finite element analyses identify that the highest stress regions are located at the vicinity of the shoulders of the fibrous cap and in the stiff calcified tissue. A parametric analysis reveals a positive correlation between the increase in lipid core portion and the mechanical stress in the fibrous cap and, hence, the risk for cap rupture. The highest values of the vulnerability index, which correlate to more vulnerable caps, are obtained for morphologies for which the lipid cores were severe; heavily loaded fibrous caps were thus detected. The proposed multidisciplinary methodology is able to investigate quantitatively the mechanical behavior of atherosclerotic plaques in patient-specific stenoses. The introduced vulnerability index may serve as a more quantitative tool for diagnosis, treatment and prevention.

A New Geometric Model of Laid-in Weft-Knitted Fabrics

2021 ◽  
pp. 004051752199276
Author(s):  
Ki Wai Fong ◽  
Si Qing Li ◽  
Rong Liu
Keyword(s):  
Cost Estimation ◽  
Geometric Model ◽  
Three Dimensional ◽  
Wearable Electronics ◽  
Material Consumption ◽  
Knitted Fabrics ◽  
Functional Textiles ◽  
Loop Pattern ◽  
Spatial Configurations ◽  
Consumption Prediction

Inlay yarn and laid-in structures are important technical knitting elements that have been increasingly applied in the structural design of functional textiles in industrial, medical, and wearable electronics fields. However, there is no currently established geometric model to numerically analyze their spatial morphologies and structural properties. This study presents a new geometric model and numerical analysis approach to characterize spatial configurations of inlay yarn and ground yarn in a three-dimensional scenario for laid-in weft-knitted fabrics. Loop lengths of the inlay and ground yarn materials were calculated and analyzed under different contact and deformation conditions to estimate material consumption in this complex interlooping layout. Series of laid-in weft-knitted fabrics made of different combinations of ground and inlay yarns were fabricated with the 1 × 1 laid-in loop pattern and tested for the model validation. The comparisons between the experimental and calculated results indicated that the newly developed geometric model favorably agreed with the experimental measurements regarding the ground loop lengths and inlay loop lengths applied in the laid-in weft-knitted structures. The results indicated the applicability of the developed geometric model of laid-in weft-knitted fabrics with similar structural patterns in practical use. The output of this study provides a theoretical and practical reference for structural and physical properties analysis, material consumption prediction, even cost estimation of laid-in weft-knitted fabrics.

scholarly journals Recurrent contracted sockets treated with personalized, three-dimensionally printed conformers and buccal grafts

2021 ◽  
pp. 112067212110000
Author(s):  
Annabel LW Groot ◽  
Jelmer S Remmers ◽  
Roel JHM Kloos ◽  
Peerooz Saeed ◽  
Dyonne T Hartong
Keyword(s):  
Three Dimensional ◽  
Case Series ◽  
Secondary Outcome ◽  
Retrospective Case ◽  
Upper Eyelid ◽  
Ocular Prosthesis ◽  
Buccal Mucosal Graft ◽  
Custom Made ◽  
3D Printed

Purpose: Recurrent contracted sockets are complex situations where previous surgeries have failed, disabling the wear of an ocular prosthesis. A combined method of surgery and long-term fixation using custom-made, three-dimensional (3D) printed conformers is evaluated. Methods: Retrospective case series of nine patients with recurrent excessive socket contraction and inability to wear a prosthesis, caused by chemical burns ( n = 3), fireworks ( n = 3), trauma ( n = 2) and enucleation and radiotherapy at childhood due to optic nerve glioma ( n = 1) with three average previous socket surgeries (range 2–6). Treatment consisted of a buccal mucosal graft and personalized 3D-printed conformer designed to be fixated to the periosteum and tarsal plates for minimal 2 months. Primary outcome was the retention of an ocular prosthesis. Secondary outcome was the need for additional surgeries. Results: Outcomes were measured at final follow-up between 7 and 36 months postoperatively (mean 20 months). Eight cases were able to wear an ocular prosthesis after 2 months. Three cases initially treated for only the upper or only the lower fornix needed subsequent surgery for the opposite fornix for functional reasons. Two cases had later surgery for cosmetic improvement of upper eyelid position. Despite pre-existing lid abnormalities (scar, entropion, lash deficiency), cosmetic outcome was judged highly acceptable in six cases because of symmetric contour and volume, and reasonably acceptable in the remaining two. Conclusions: Buccal mucosal transplant fixated with a personalized 3D-designed conformer enables retention of a well-fitted ocular prosthesis in previously failed socket surgeries. Initial treatment of both upper and lower fornices is recommended to avoid subsequent surgeries for functional reasons.

scholarly journals Simulation and Analysis of Floodlighting Based on 3D Computer Graphics

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1042
Author(s):  
Rafał Krupiński
Keyword(s):  
Computer Graphics ◽  
External Surface ◽  
Geometric Model ◽  
Three Dimensional ◽  
Fold Increase ◽  
Luminance Level ◽  
Object Model ◽  
Geometric Mesh ◽  
Average Luminance ◽  
To Receive

The paper presents the opportunities to apply computer graphics in an object floodlighting design process and in an analysis of object illumination. The course of object floodlighting design has been defined based on a virtual three-dimensional geometric model. The problems related to carrying out the analysis of lighting, calculating the average illuminance, luminance levels and determining the illuminated object surface area are also described. These parameters are directly tied with the calculations of the Floodlighting Utilisation Factor, and therefore, with the energy efficiency of the design as well as the aspects of light pollution of the natural environment. The paper shows how high an impact of the geometric model of the object has on the accuracy of photometric calculations. Very often the model contains the components that should not be taken into account in the photometric calculations. The research on what influence the purity of the geometric mesh of the illuminated object has on the obtained results is presented. It shows that the errors can be significant, but it is possible to optimise the 3D object model appropriately in order to receive the precise results. For the example object presented in this paper, removing the planes that do not constitute its external surface has caused a two-fold increase in the average illuminance and average luminance. This is dangerous because a designer who wants to achieve a specific average luminance level in their design without optimizing the model will obtain the luminance values that will actually be much higher.

Insight into Bile Duct Reaction to Obstruction from a Three-dimensional Perspective Using ex Vivo Phase-Contrast CT

Radiology ◽  
2021 ◽  
pp. 203967
Author(s):  
Wen-Juan Lv ◽  
Xin-Yan Zhao ◽  
Dou-Dou Hu ◽  
Xiao-Hong Xin ◽  
Li-Li Qin ◽  
...  
Keyword(s):  
Bile Duct ◽  
Phase Contrast ◽  
Ex Vivo ◽  
Three Dimensional ◽  
Contrast Ct ◽  
Insight Into

The Vehicle Dynamical Analysis of a High-Speed Train Passing through a Tunnel

2010 ◽  
Vol 29-32 ◽  
pp. 835-840 ◽  
Author(s):  
Zhi Peng Feng ◽  
Ji Ye Zhang ◽  
Wei Hua Zhang
Keyword(s):  
High Speed ◽  
Stokes Equations ◽  
Geometric Model ◽  
Three Dimensional ◽  
Grid Method ◽  
Dynamical Analysis ◽  
High Speed Train ◽  
Flow Induced Vibration ◽  
Running Safety ◽  
Dynamics Calculation

As the speed of train increases, flow-induced vibration of trains passing through tunnels has become a subject of discussion, to investigate this phenomenon, a simplified geometric model and a vehicle dynamics model of a high-speed train traveling through a tunnel were built. To analyze the unsteady three-dimensional flow around the train, the 3-D, transient, viscous, compressible Reynolds-averaged Navier-Stokes equations combined with the k- two-equation turbulence model were solved with the finite volume method. The motion of the train was carried out using the technique of sliding grid method. The dynamics response of the train was obtained by means of the computational multi-body dynamics calculation. Meanwhile the running safety and riding comfort of the train were analyzed. With the numerical simulation, the variation of aerodynamic forces was obtained. The research founds that, vibration of the train increases drastically during it passing through a tunnel. The running safety and riding quality of the train are reduced greatly but they are in the safe range.

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