scholarly journals Iterative Methods for the Biomechanical Evaluation of Corneal Response. A Case Study in the Measurement Phase

2021 ◽  
Vol 11 (22) ◽  
pp. 10819
Author(s):  
Carmelo Gómez ◽  
David P. Piñero ◽  
Manuel Paredes ◽  
Jorge L. Alió ◽  
Francisco Cavas
Keyword(s):  
Stress Distribution ◽  
Geometric Model ◽  
Patient Specific ◽  
Biomechanical Models ◽  
Secondary Interventions ◽  
Key Factor ◽  
Mechanical Models ◽  
Biomechanical Evaluation ◽  
Stress And Strain Distribution

the number of corneal surgeries steadily grew in recent years and boosted the development of corneal biomechanical models. These models can contribute to simulating surgery by reducing associated risks and the need for secondary interventions due to ectasias or other problems related to correcting other diseases. Biomechanical models are based on the geometry obtained with corneal topography, which is affected by intraocular pressure and material properties. Knowledge of stress distribution in the measurement phase is a key factor for improving the accuracy of in silico mechanical models. In this work, the results obtained by two different methods: prestress method and displacements method were compared to evaluate the stress and strain distribution in a general geometric model based on the Navarro eye geometry and two real corneal geometries. The results show that both methods are equivalent for the achievement of the stress distribution in the measurement phase. Stress distribution over the corneal geometry in the measurement phase is a key factor for accurate biomechanical simulations, and these simulations could help to develop patient-specific models and reduce the number of secondary interventions in clinical practice.

scholarly journals Complex wall modeling for hemodynamic simulations of intracranial aneurysms based on histologic images

2021 ◽  
Vol 16 (4) ◽  
pp. 597-607
Author(s):  
Annika Niemann ◽  
Samuel Voß ◽  
Riikka Tulamo ◽  
Simon Weigand ◽  
Bernhard Preim ◽  
...  
Keyword(s):  
Wall Thickness ◽  
Vessel Wall ◽  
Intracranial Aneurysms ◽  
Geometric Model ◽  
Image Data ◽  
Outer Wall ◽  
3D Models ◽  
Patient Specific ◽  
Intracranial Vessel ◽  
Hemodynamic Simulations

Abstract Purpose For the evaluation and rupture risk assessment of intracranial aneurysms, clinical, morphological and hemodynamic parameters are analyzed. The reliability of intracranial hemodynamic simulations strongly depends on the underlying models. Due to the missing information about the intracranial vessel wall, the patient-specific wall thickness is often neglected as well as the specific physiological and pathological properties of the vessel wall. Methods In this work, we present a model for structural simulations with patient-specific wall thickness including different tissue types based on postmortem histologic image data. Images of histologic 2D slices from intracranial aneurysms were manually segmented in nine tissue classes. After virtual inflation, they were combined into 3D models. This approach yields multiple 3D models of the inner and outer wall and different tissue parts as a prerequisite for subsequent simulations. Result We presented a pipeline to generate 3D models of aneurysms with respect to the different tissue textures occurring in the wall. First experiments show that including the variance of the tissue in the structural simulation affect the simulation result. Especially at the interfaces between neighboring tissue classes, the larger influence of stiffer components on the stability equilibrium became obvious. Conclusion The presented approach enables the creation of a geometric model with differentiated wall tissue. This information can be used for different applications, like hemodynamic simulations, to increase the modeling accuracy.

scholarly journals Optimize Design of Run-Flat Tires by Simulation and Experimental Research

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 474
Author(s):  
Huaqiao Liu ◽  
Yiren Pan ◽  
Huiguang Bian ◽  
Chuansheng Wang
Keyword(s):  
Stress Distribution ◽  
Energy Loss ◽  
Successful Implementation ◽  
Performance Tests ◽  
Key Factors ◽  
Heat Accumulation ◽  
Factors Affecting ◽  
Structural Rigidity ◽  
Key Factor ◽  
Durability Testing

In this study, the two key factors affecting the thermal performance of the insert rubber and stress distribution on the tire sidewall were analyzed extensively through various performance tests and simulations to promote the development of run-flat tires. Four compounds and two structures of insert rubber were designed to investigate the effects of heat accumulation and stress distribution on durability testing at zero pressure. It was concluded that the rigidity and tensile strength of the compound were negatively correlated with temperature. The deformation was a key factor that affects energy loss, which could not be judged solely by the loss factor. The stress distribution, however, should be considered in order to avoid early damage of the tire caused by stress concentration. On the whole, the careful balance of mechanical strength, energy loss, and structural rigidity was the key to the optimal development of run-flat tires. More importantly, the successful implementation of the simulations in the study provided important and useful guidance for run-flat tire development.

scholarly journals A model order reduction approach to create patient-specific mechanical models of human liver in computational medicine applications

2019 ◽  
Vol 170 ◽  
pp. 95-106 ◽  
Author(s):  
Nathan Lauzeral ◽  
Domenico Borzacchiello ◽  
Michael Kugler ◽  
Daniel George ◽  
Yves Rémond ◽  
...  
Keyword(s):  
Human Liver ◽  
Model Order Reduction ◽  
Order Reduction ◽  
Patient Specific ◽  
Model Order ◽  
Mechanical Models ◽  
Reduction Approach

scholarly journals Procedure for the Selection of Rubber Compound in Rubber-Metal Springs for Vibration Isolation

Polymers ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 1737
Author(s):  
Milan Banić ◽  
Dušan Stamenković ◽  
Aleksandar Miltenović ◽  
Dragan Jovanović ◽  
Milan Tica
Keyword(s):  
Numerical Simulation ◽  
Constitutive Model ◽  
Vibration Isolation ◽  
Correct Selection ◽  
Virtual Experiment ◽  
Rubber Compound ◽  
Key Factor ◽  
Railway Engineering ◽  
Selection Of

The selection of a rubber compound has a determining influence on the final characteristics of rubber-metal springs. Therefore, the correct selection of a rubber compound is a key factor for development of rubber-metal vibration isolation springs with required characteristics. The procedure for the selection of the rubber compound for vibration isolation of rubber-metal springs has been proposed, so that the rubber-metal elements have the necessary characteristics, especially in terms of deflection. The procedure is based on numerical simulation of spring deflection with Bergström-Boyce constitutive model in virtual experiment, with a goal to determine which parameters of the constitutive model will lead to spring required deflection. The procedure was verified by case study defined to select rubber compound for a rubber–metal spring used in railway engineering.

scholarly journals An Optimization Workflow in Design for Additive Manufacturing

2021 ◽  
Vol 11 (6) ◽  
pp. 2572
Author(s):  
Stefano Rosso ◽  
Federico Uriati ◽  
Luca Grigolato ◽  
Roberto Meneghello ◽  
Gianmaria Concheri ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Structural Optimization ◽  
Geometric Model ◽  
Complex Geometries ◽  
Design Phase ◽  
Design For Additive Manufacturing ◽  
Engineering Software ◽  
Embodiment Design ◽  
Pros And Cons

Additive Manufacturing (AM) brought a revolution in parts design and production. It enables the possibility to obtain objects with complex geometries and to exploit structural optimization algorithms. Nevertheless, AM is far from being a mature technology and advances are still needed from different perspectives. Among these, the literature highlights the need of improving the frameworks that describe the design process and taking full advantage of the possibilities offered by AM. This work aims to propose a workflow for AM guiding the designer during the embodiment design phase, from the engineering requirements to the production of the final part. The main aspects are the optimization of the dimensions and the topology of the parts, to take into consideration functional and manufacturing requirements, and to validate the geometric model by computer-aided engineering software. Moreover, a case study dealing with the redesign of a piston rod is presented, in which the proposed workflow is adopted. Results show the effectiveness of the workflow when applied to cases in which structural optimization could bring an advantage in the design of a part and the pros and cons of the choices made during the design phases were highlighted.

scholarly journals Why We Go Where We Go: Profiling User Decisions on Choosing POIs

2020 ◽  
Author(s):  
Renjun Hu ◽  
Xinjiang Lu ◽  
Chuanren Liu ◽  
Yanyan Li ◽  
Hao Liu ◽  
...  
Keyword(s):  
Key Factors ◽  
Real World Data ◽  
Decision Factors ◽  
Point Of Interest ◽  
Learning Factor ◽  
Poi Recommendation ◽  
Key Factor ◽  
Selection Of ◽  
Decision Structures

While Point-of-Interest (POI) recommendation has been a popular topic of study for some time, little progress has been made for understanding why and how people make their decisions for the selection of POIs. To this end, in this paper, we propose a user decision profiling framework, named PROUD, which can identify the key factors in people's decisions on choosing POIs. Specifically, we treat each user decision as a set of factors and provide a method for learning factor embeddings. A unique perspective of our approach is to identify key factors, while preserving decision structures seamlessly, via a novel scalar projection maximization objective. Exactly solving the objective is non-trivial due to a sparsity constraint. To address this, our PROUD adopts a self projection attention and an L2 regularized sparse activation to directly estimate the likelihood of each factor to be a key factor. Finally, extensive experiments on real-world data validate the advantage of PROUD in preserving user decision structures. Also, our case study indicates that the identified key decision factors can help us to provide more interpretable recommendations and analyses.

scholarly journals MOTIF PEREMPUAN BERKENDARA SEPEDA MOTOR TANPA HELM: STUDI KASUS DI KOTA SIDOARJO, JAWA TIMUR

2018 ◽  
Vol 1 (2) ◽  
pp. 72
Author(s):  
Irvan Rifai ◽  
Fajar Santoso
Keyword(s):  
Focus Group ◽  
Group Discussion ◽  
Primary Data ◽  
Focus Group Discussions ◽  
Group Discussions ◽  
Social Rules ◽  
Online Newspapers ◽  
Primary Data Analysis ◽  
Key Factor

This case study is aimed at revealing motives of women riding motor bike without helmet in Sidoarjo, East Java. The data in this study are garnered through interviews, focus group discussions, observation, and artefact including online newspapers, whilst thematic analysis is utilised as a primary data analysis. The findings of the study indicate that; first, distance from home to school is a most salient motive of women riding bike without helmet. Second, the absence of policeman on the street is a key factor of not wearing helmet. Third, social identity is another reason for not wearing helmet. Fourth, styles and its influence of feeling discomfort of wearing helmet. Fifth, social rules and its impracticality of not wearing helmet. The findings of this study are expected to have contributions of the ways to educate people about safety riding by involving students, students’ parents, teachers and or stakeholders. This study, however, cannot represent all women perspectives of not wearing helmet when riding motor bike within Indonesia. Further research, therefore, is expected to consider areas and characteristics which might differ from the present study. Penelitian ini bertujuan untuk mengungkap motif perempuan pengendara sepeda motor tanpa helm di daerah Kabupaten Sidoarjo, Jawa Timur, dengan menggunakan metode wawancara, Focus Group Discussion, observasi, dan analisis terhadap tulisan-tulisan yang ada di media sosial, seperti koran online. Analisis yang dilakukan menggunakan metode analisis tematik. Dari hasil analisis data diperoleh 5 tema yang menjadi pembahasan pada penelitian ini, yaitu: pertama, Jarak dari rumah ke sekolah menjadi pertimbangan utama responden tidak memakai helm; kedua, Kehadiran aparat kepolisian dan motif tidak memakai helm; ketiga, Identitas sosial sebagai alasan tidak memakai helm; keempat, style dan pengaruh ketidaknyamanan memakai helm; dan ke lima, aturan sosial dan ketidakpraktisan memakai helm. Hasil penelitian ini diharapkan bisa memberikan kontribusi informasi terhadap upaya mengedukasi masyarakat dalam keselamatan berkendara sepeda motor dengan melibatkan peran serta siswa, orang tua siswa, guru dan pemangku kepentingan. Namun demikian, dikarenakan penelitian ini terbatas pada studi kasus di Kota Sidoarjo, terdapat kemungkinan bahwa hasil yang diperoleh tidak dapat merepresentasikan perspektif perempuan pengendara sepeda motor di kota-kota lain di Indonesia. Untuk itu, penelitian ini diharapkan dapat dilanjutkan untuk kota-kota yang mempunya karakteristik berbeda dengan lokasi penelitian ini.

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