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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
291

Deformačně napěťová analýza femuru s distrakčním intramedulárním hřebem / Strain and stress analysis of the femur with distraction intramedullary nail

Konvalinka, Jan January 2017 (has links)
This master's thesis is focused on determination and analysis of stress and strain in femur with distraction intramedullary nail for treating leg length discrepancy with the method of distraction osteogenesis. Thesis is mainly focused on states after distraction when the callus consolidates. Problem of determining stress and strain is solved by computational modeling using FEM. Detailed description of modeling is included in this thesis, complicated 3D geometry of bone was acquired from segmentation of CT images. Computational model is solve with 4 different types of callus geometry and also material properties of callus are varied. The influence on stress and strain when the middle distal screw is not applied is also analyzed.
292

Tepelná analýza servo motoru / Thermal analyses of servo motor

Kratochvila, Lukáš January 2017 (has links)
This Master’s thesis is focused on thermal analyses of servomotors per computational modeling with finite element method. The goal was to set the model for the analyses and verify it with experiment and evaluate achieved results.
293

Deformačně napěťová analýza tumorózní totální endoprotézy kyčelního kloubu / Stress-strain analysis of tumorous total endoprosthesis of hip joint

Vystrk, Tomáš January 2018 (has links)
Tumorous total endoprosthesis of hip joint is used for reconstruction of the limb affected by bone tumor and to regain its functnion. Longterm load conditions must be considered by the reconstruction and the joint mobility must be enabled. Suitability of the endoprosthesis depends on its construction considering shape, material and with this related mechanical properties. This thesis deals with creation of computational model and stress-strain analysis of tumorous total endoprosthesis of hip joint. There are two different types of endoprosthesis modeled in this thesis, each with three different length of resected bone replacement. Based on stress-strain analysis an assessment of possible limit states is made.
294

Deformačně-napěťová analýza fixace kostí palce nohy / Strain-stress analysis of fixed bone of foot

Zapletal, Jakub January 2018 (has links)
This diploma thesis deals with analysis of the rigidity of different variations of foot fixations. In the thesis there is a description of elementary anatomy of foot and its patology. Furthermore the possible corrections of hallux deformities and chosen fixators are described. The problem of analysis is soluted by the method of finite elements. The thesis also includes steps of geometery model creation based on 3D scanning. Three differents types of fixations are compared in this thesis and each of them is created in two different levels of details. There is a comparation, analysis of final solutions and chosen influences on the rigidity in the conclusion.
295

Deformační a napěťová analýza dlahy fixující zlomeninu vřetenní kosti / Stress-strain analysis of internal plate fixator of distal radius fracture

Hussliková, Veronika January 2020 (has links)
Distal radius fractures are one of the most common fractures. In case of a complicated fracture, it is necessary to proceed with surgical treatment using an internal plate fixator. The aim of this thesis was to perform a stress-strain analysis of an internal plate fixator attached to the distal radius using bone screws. Computational modeling using finite element method was used to assess the mechanical interactions among the individual elements of this system. The stress-strain analysis was performed for three different types of fixation in geometry models including a distal radius fracture and a healed distal radius and for three different types of loads. In the evaluation of the results, the influence of the type of load and the influence of the healing of the bone tissue were assessed. For the bending load, which was the most critical, the yield strength was not exceeded in the plate or in the bone screws, and therefore irreversible plastic deformation of the material did not occur.
296

Výpočtové modelování mechanických zkoušek živočišné buňky / Computational modelling of mechanical tests of animal cell

Orlová, Lucie January 2021 (has links)
Předkládaná diplomová práce se zabývá stavbou živých živočišných buněk a jejich odezvou na mechanické zatěžování. Zobecněným zaměřením práce je popis mechanického chování buňky nejenom ve fyziologickém, ale i v patologickém stavu. Výchozím předpokladem pro úspěšné řešení zadané úlohy je vysoce interdisciplinární přístup kombinující výpočtové přístupy mechaniky těles (v~tomto případě metodu konečných prvků) s lékařským výzkumem. Nejdůležitějším bodem při tvorbě výpočtového modelu, pomocí něhož je možné aproximovat chování živé buňky při zatížení, je zejména identifikace mechanicky významných komponent a~jejich materiálových parametrů. V tomto případě jsou jako mechanicky význačné identifikovány spojité součásti jádro, membrána a cytoplazma, které jsou nově propojeny s prvky diskrétními (mitochondriální sítí) v hybridním modelu, jehož platnost je ověřena pomocí experimentálních dat. Tento model slouží jako podklad k vyhodnocení míry vlivu mitochondrií na celkovou tuhost buňky.
297

Výpočtové modelování interakce proudící krve s trubicí tepny s ateromem / Computational modeling of the interaction of flowing blood with the artery tube with the atheroma

Freiwald, Michal January 2021 (has links)
Předložená diplomová práce se zabývá interakcí mezi proudící krví a krční tepnou, obsahující aterosklerotický plat, za pomoci konečnoprvkové fluid-structure interaction analýzy. První část práce obsahuje souhrn teoretických poznatků, sestávající z kardiovaskulárního systému, cév, souvisejících konstitutivních modelů, reologie krve a úvodu do teorie proudění. Dále je v práci obsažen stručný souhrn současného poznání výpočtového modelování v této oblasti, s důrazem na strukturní a fluid-structure interaction analýzy v oblasti krční tepny, a na použité konstitutivní modely. Experimentální část se soustředí na tvorbu zjednodušeného modelu krční tepny, obsahující aterosklerotický plat, a na tvorbu odpovídajícího modelu krve. Oba modely poté společně vstupují do fluid-structure interaction analýzy, která si klade za cíl pochopit důsledky pulzujícího toku krve na stěnu tepny a na růst aterosklerotického plátu; primárními zkoumanými veličinami jsou první hlavní napětí na stěně tepny, celková deformace stěny tepny, časově zprůměrovaná hodnota smykového napětí na stěně tepny a oscilační smykový index. Všechny výsledky jsou porovnány napříč několika typy analýz, tak aby bylo možné zhodnotit rozdíly a důsledky zvoleného přístupu. Součástí práce je také zjednodušená parametrická studie, která porovnává vliv rostoucího procenta stenózy na vyhodnocované veličiny. V poslední částí práce jsou zhodnoceny výsledky, její limitace a další možnosti výzkumu v této oblasti.
298

Cognitive Modeling for Human-Automation Interaction: A Computational Model of Human Trust and Self-Confidence

Katherine Jayne Williams (11517103) 22 November 2021 (has links)
Across a range of sectors, including transportation and healthcare, the use of automation to assist humans with increasingly complex tasks is also demanding that such systems are more interactive with human users. Given the role of cognitive factors in human decision-making during their interactions with automation, models enabling human cognitive state estimation and prediction could be used by autonomous systems to appropriately adapt their behavior. However, accomplishing this requires mathematical models of human cognitive state evolution that are suitable for algorithm design. In this thesis, a computational model of coupled human trust and self-confidence dynamics is proposed. The dynamics are modeled as a partially observable Markov decision process that leverages behavioral and self-report data as observations for estimation of the cognitive states. The use of an asymmetrical structure in the emission probability functions enables labeling and interpretation of the coupled cognitive states. The model is trained and validated using data collected from 340 participants. Analysis of the transition probabilities shows that the model captures nuanced effects, in terms of participants' decisions to rely on an autonomous system, that result as a function of the combination of their trust in the automation and self-confidence. Implications for the design of human-aware autonomous systems are discussed, particularly in the context of human trust and self-confidence calibration.
299

Napjatostní analýza keramické hlavice totální kyčelní endoprotézy zatížené dle ISO 7206-5 / Stress analysis of the total hip joint endoprosthesis head under ISO 7206-5 loading

Varga, Jozef January 2008 (has links)
The aim of this work is to analyse axisymetric tasks by norm ISO 7206-5, which is used to determination of static strength of ceramic heads. In the numeric analysis there will be considered form variances from nominal conicalness and circularity of stem sections i.e. possible variances caused by production. Furthermore form changes of recess inside of the head measured on real samples will be considered. All these variances from nominal values are necessary to analyse in more details, because they can participate in destruction of ceramic heads. The stem system, ceramic head and load cone (DHK) will be simulated as a 2D axisymetric task and 3D quarter symetrical task. That is why is necessary to undertake also comparing analysis of 2D and 3D tasks and compare results or eventually evaluate the error. This problem is solved using of Finite element System ANSYS 11.0.
300

Analýza zbytkových napětí ve stěně tepny / Analysis of residual stresses in arterial wall

Novák, Kamil January 2013 (has links)
This thesis deals with computational modeling of the influence of residual stresses in idealized geometry of blood vessels and subsequent application of acquired knowledge to abdominal aortic aneurysm. In the terms of quality of the computational model, we reduced the uncertainties that are included in the computational model without considering the influence of residual stresses. The basic assumption of homogenization significant peaks of the stress between inner and outer vessel wall was met for each level of the computational model Methods that have been used are: deformation method (opening angle method), inverse mechanics of large deformations, fictitious temperature – for linear elastic material and hyperelastic material defined by the constitutive model. Numerical verification was carried out using program ANSYS.

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