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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.
1

Quantification et modélisation des forces et des moments appliqués à l'intérieur des attaches orthodontiques placées sur une arcade dentaire dans les trois dimensions de l'espace / Experimental and numerical quantification of forces and moments applied into orthodontic brackets placed on a 3D-dental arch

Wagner, Delphine 03 July 2018 (has links)
Les appareils orthodontiques appliquent une force prolongée sur les dents, conduisant au mouvement dentaire provoqué, à l'aide d'arcs insérés à l'intérieur d'attaches. Le déplacement dentaire résulte de la biomécanique mais également des réponses biologiques des tissus de soutien. Notre problématique porte sur les efforts mécaniques présents à l'intérieur des attaches orthodontiques, lors de l'insertion d'un fil à mémoire de forme. Nous souhaitons quantifier les forces et moments à l'échelle d'une arcade dentaire en trois dimensions. Notre travail présente un protocole alliant expérimentation et modélisation numérique. Cette méthodologie innovante permet de mettre en évidence les forces et moments appliqués lors de la première phase d'un traitement orthodontique à l'insertion d'un arc nickel-titane de diamètre 0,356 mm (0 .014 inch) dans des gorges de diamètre 0,457x0,635 mm (0.018x0.025) sur une arcade maxillaire, obtenue après segmentation d'une imagerie tridimensionnelle d'un patient. Cette première étape ouvre les portes vers une individualisation des traitements orthodontiques par l'application des efforts mécaniques nécessaires sans être délétères. / Prolonged forces are applied on the teeth by orthodontie deviees, using arch wires inserted into brackets, leading to the orthodontie teeth movements. This displacement is the result of biomechanics but also the biological responses of the surrounding periodontal tissues. Our aim is to quantify the forces and moments applied on the orthodontie brackets, during the insertion of a shape memory alloy, at the scale of a three-dimensional dental arch. Our work presents a protocol combining experimentation and numerical modelling. This innovative methodology enables measuring the forces and moments applied during the first stage of an orthodontie treatment, when a 0.014-inch nickel-titanium arch wire is inserted into a maxillary arch. This first step will help in the definition of individualized treatments, applying the necessarymechanical forces without being iatrogenic.
2

Is my musculoskeletal model complex enough? The implications of six degree of freedom lower limb joints for dynamic consistency and biomechanical relevance

Pearl, Owen Douglas January 2020 (has links)
Studies have shown that modeling errors due to unaccounted for soft-tissue deformations – known as soft-tissue artifact (STA) – can reduce the efficacy and usefulness of musculoskeletal simulations. Recent work has proven that adding degrees of freedom (DOF) to the joint definitions of a musculoskeletal model’s lower limbs can significantly change the prediction of an individual’s kinematics and dynamics while simultaneously improving estimates of their mechanical work. This indicates that additional modeling complexity may mitigate the effects of STA. However, it remains to be determined whether adding DOF to the lower limb joints can impact a model’s satisfaction of Newton’s Second Law of Motion, or whether a specific number of DOF must be incorporated in order to produce the most biomechanically accurate simulations. To investigate these unknowns, I recruited ten subjects of variable body-mass-indices (BMI) and recorded subject walking data at three speeds normalized by Froude number (Fr) using optical motion capture and an instrumented treadmill (eight male, two females; mean ± s.d.; age 21.6 ± 2.87 years; BMI 25.1 ± 5.1). Then, I added DOF to the lower limb joints of OpenSim’s 23 DOF lower body and torso model until it minimized the magnitude of the pelvis residual forces and moments for a single, representative subject trial (BMI = 24.0, Fr = 0.15). These artificial residual forces and moments are applied at the pelvis to maintain the model’s orientation in space by satisfying Newton’s Second Law. Finally, I simulated all 30 trials with both the original and the edited model and observed how the biomechanical predictions of the two models differed over the range of subject BMIs and walking speeds. After applying both the original and the edited model to the entire data set, I found that the edited model resulted in statistically lower (α = 0.05) residual forces and moments in four of the six directions. Then, after investigating the impact of changes in BMI and Froude number on these residual reductions, I found that two of the six directions exhibited statistically significant correlations with Froude number while none of the six possessed correlations with BMI. Therefore, adding DOF to the lower limb joints can improve a model’s dynamic consistency and combat the effects of STA, and simulations of higher speed behaviors may benefit more from additional DOF. For BMI, it remains to be determined if a higher BMI indicates greater potential for residual reduction, but it was shown that this method of tuning the model for one representative subject was agnostic to BMI. Overall, the method of tuning the model for one representative subject was found to be quite limited. There were multiple subject trials for which reduced residuals corresponded to drastic changes in kinematic and dynamic estimates until they were no longer representative of normal human walking. Therefore, it is possible to improve dynamic consistency by adding DOF to the lower limb joints. But, for biomechanically relevant estimates to be consistently preserved and soft-tissue artifact to be completely minimized, subject-specific model tuning is likely necessary. / Mechanical Engineering
3

Comparison of Strain Gage and Fiber Optic Sensors On A Sting Balance In A Supersonic Wind Tunnel

Edwards, Alex T. 05 January 2001 (has links)
Force and moment balances have proved to be essential in the measurement and calculation of aerodynamic properties during wind tunnel testing. With the recent advancements of technology, new fiber optic sensors have been designed to replace the conventional foil strain gage sensors commonly found on balances, thereby offering several distinct advantages. The use of fiber optic sensors on a balance brings with it some potential advantages over conventional strain gage balances including increased resolution and accuracy, insensitivity to electromagnetic interference, and the capability of use at high temperatures. By using the fiber optic sensors, some of the limitations of the conventional balance can be overcome, leading to a better overall balance design. This thesis considers an initial trial application of new fiber optic sensors on a conventional, six-component sting balance while retaining the original foil strain gage sensors for comparison. Tests were conducted with a blunt, 10º half-angle cone model in the Virginia Tech 9x9 inch Supersonic Wind Tunnel at Mach 2.4 with a total pressure of 48 psia and ambient total temperature of 25.3ºC. Results showed a close comparison between the foil strain gages and the fiber optic sensor measurements, which were set up to measure the normal force and pitching moment on the blunt cone model. A Finite Element Model (FEM) of the sting balance was produced in order to determine the best locations for the fiber optic sensors on the sting balance. Computational Fluid Dynamics (CFD) was also used in order to predict and compare the results acquired from all of the sensors. / Master of Science
4

Forças, momentos e coeficiente de atrito em teste de três pontos e em teste de resistência ao deslizamento com braquetes autoligáveis e fios 0.014\" utilizando um novo dispositivo / Forces, moments and coefficient of friction in three-bracket bending test and in resistance to sliding test with self-ligating brackets and wires 0.014\'\' using a new device

Freitas, Ana Carolina Carneiro de 26 January 2016 (has links)
O objetivo principal do estudo é comparar o teste em 3 pontos com braquetes com o teste de resistência ao deslizamento utilizando um novo dispositivo que realiza a mensuração simultânea do coeficiente de atrito, das forças e dos momentos nos braquetes de ancoragem e da força de desativação no braquete desalinhado, exercidos por fios ortodônticos. Os objetivos secundários foram desenvolver o dispositivo e comparar, no teste em 3 pontos: (i) a influência, nas grandezas e no coeficiente de atrito cinético, da variação da simetria nas distâncias inter-braquetes, do tipo de braquete de ancoragem (canino ou 2º pré-molar), do deslocamento (3 ou 5mm) do braquete central, do sentido do desalinhamento (vestibular ou lingual) do braquete central e da marca de fio-braquete; (ii) as 3 formas de cálculo do coeficiente de atrito cinético; (iii) os 10 ciclos, para vestibular ou lingual, para verificar se eles são semelhantes ou não entre si. Foram utilizados braquetes autoligáveis (dentes 13, 14 e 15) e fios 0.014\'\' NiTi e CuNiTi das marcas Aditek e Ormco. O teste de resistência ao deslizamento foi realizado no desalinhamento lingual, nos dois deslocamentos e na configuração simétrica. O teste em 3 pontos com braquetes foi realizado no desalinhamento lingual e vestibular, nos dois deslocamentos e na configuração simétrica e assimétrica. Por meio da ANOVA, foram comparados, entre os dois tipos de teste: (A) as grandezas e o coeficiente de atrito e (B) o coeficiente de atrito gerado apenas no braquete de 2º pré-molar. Utilizando-se do mesmo teste estatístico foram comparados, no teste em 3 pontos com braquetes: (A) na configuração simétrica, algumas grandezas e o coeficiente de atrito advindos da variação da marca de fio-braquete, do deslocamento, do desalinhamento e do tipo de braquete; (B) algumas grandezas e o coeficiente de atrito gerados na configuração simétrica e assimétrica; (C) os valores das 3 formas de cálculo do coeficiente de atrito na configuração simétrica; e (D) algumas grandezas e o coeficiente de atrito encontrados nos 10 ciclos. Resultados: (A) a maioria dos valores das grandezas e do coeficiente de atrito gerados pelos dois tipos de teste foram diferentes estatisticamente; (B) o braquete de 2º pré-molar apresentou valores de coeficiente de atrito diferentes entre os dois tipos de teste; (C) na configuração simétrica, as variáveis foram estatisticamente significantes na maioria dos casos para as grandezas analisadas e para o coeficiente de atrito; (D) houve diferença entre a configuração simétrica e assimétrica; (E) o coeficiente de atrito baseado nas duas normais e na força de atrito se aproximou mais da realidade clínica e foi sensível à variação da geometria da relação fio-braquete; e (F) os 10 ciclos para lingual foram semelhantes entre si em 70% dos casos e os 10 ciclos para vestibular foram diferentes em 57% dos casos. Conclusões: o teste em 3 pontos com braquetes é diferente do teste de resistência ao deslizamento; a variação das configurações geométricas e da marca de fio-braquete pode influenciar nos valores das grandezas e do coeficiente de atrito cinético; os 10 ciclos para lingual foram mais semelhantes entre si que os 10 ciclos para vestibular. / The main objective of the study is to compare the three-bracket bending test with the resistance to sliding test using a new device that performs simultaneous measurement of coefficient of friction, the forces and moments on the anchor brackets and deactivation force in misaligned bracket, exercised by orthodontic wires. Secondary objectives were to develop the device and compare, in the three-bracket bending test: (i) the influence, on the physical quantities and on the kinetic friction coefficient, of the variation of the symmetry in the inter-bracket distance, of the type of anchor bracket (canine or 2nd premolar), of displacement (3 or 5mm) and misalignment (buccal or lingual) of the central bracket, and of the wire and bracket brand; (ii) the three ways to calculate the coefficient of kinetic friction; (iii) the 10 cycles, for buccal or lingual, to see if they are similar or not. Self-ligating brackets were used (teeth 13, 14 and 15) and wires 0.014 \'\' NiTi and CuNiTi of Aditek and Ormco brands. The resistance to sliding test was conducted on the lingual misalignment, on both displacements and on symmetrical configuration. The three-bracket bending test was held at the lingual and vestibular misalignment, at both displacements and at the symmetrical and asymmetrical configuration. Through ANOVA, were compared, between the two types of tests: (A) the quantities and the coefficient of friction and (B) the coefficient of friction generated only in the second premolar bracket. Using the same statistical test were compared, in three-bracket bending test: (A) in symmetrical configuration, the quantities and the coefficient of friction arising from the variation in the wire and bracket brands, displacement, misalignment and the type of bracket; (B) the quantities and the coefficient of friction generated by the symmetric and asymmetric configuration; (C) the values of the three ways of calculating friction coefficient; and (D) the quantities and the coefficient of friction encountered in 10 cycles. Results: (A) most of the values of the quantities and the coefficient of friction generated by the two types of test were statistically different; (B) the 2nd premolar bracket showed different friction coefficient values between the two types of test; (C) in the symmetrical configuration, the variables were statistically significant in the most of cases for quantities and the friction coefficient; (D) was found difference between symmetric and asymmetric configuration; (E) the friction coefficient based on both normal forces and frictional force was closer to the clinical reality and was sensitive to variations in the geometry of the wire-bracket relationship; and (F) the 10 cycles for lingual were similar in 70% of cases and the 10 cycles for buccal desalignment were different in 57% of cases. Conclusions: The three-bracket bending test is different from the resistance to sliding test; the variation of geometric configurations and wire and bracket brands may influence the values of the quantities and the coefficient of kinetic friction; the 10 cycles for lingual were more similar to each other than the 10 cycles for buccal.
5

Forças, momentos e coeficiente de atrito em teste de três pontos e em teste de resistência ao deslizamento com braquetes autoligáveis e fios 0.014\" utilizando um novo dispositivo / Forces, moments and coefficient of friction in three-bracket bending test and in resistance to sliding test with self-ligating brackets and wires 0.014\'\' using a new device

Ana Carolina Carneiro de Freitas 26 January 2016 (has links)
O objetivo principal do estudo é comparar o teste em 3 pontos com braquetes com o teste de resistência ao deslizamento utilizando um novo dispositivo que realiza a mensuração simultânea do coeficiente de atrito, das forças e dos momentos nos braquetes de ancoragem e da força de desativação no braquete desalinhado, exercidos por fios ortodônticos. Os objetivos secundários foram desenvolver o dispositivo e comparar, no teste em 3 pontos: (i) a influência, nas grandezas e no coeficiente de atrito cinético, da variação da simetria nas distâncias inter-braquetes, do tipo de braquete de ancoragem (canino ou 2º pré-molar), do deslocamento (3 ou 5mm) do braquete central, do sentido do desalinhamento (vestibular ou lingual) do braquete central e da marca de fio-braquete; (ii) as 3 formas de cálculo do coeficiente de atrito cinético; (iii) os 10 ciclos, para vestibular ou lingual, para verificar se eles são semelhantes ou não entre si. Foram utilizados braquetes autoligáveis (dentes 13, 14 e 15) e fios 0.014\'\' NiTi e CuNiTi das marcas Aditek e Ormco. O teste de resistência ao deslizamento foi realizado no desalinhamento lingual, nos dois deslocamentos e na configuração simétrica. O teste em 3 pontos com braquetes foi realizado no desalinhamento lingual e vestibular, nos dois deslocamentos e na configuração simétrica e assimétrica. Por meio da ANOVA, foram comparados, entre os dois tipos de teste: (A) as grandezas e o coeficiente de atrito e (B) o coeficiente de atrito gerado apenas no braquete de 2º pré-molar. Utilizando-se do mesmo teste estatístico foram comparados, no teste em 3 pontos com braquetes: (A) na configuração simétrica, algumas grandezas e o coeficiente de atrito advindos da variação da marca de fio-braquete, do deslocamento, do desalinhamento e do tipo de braquete; (B) algumas grandezas e o coeficiente de atrito gerados na configuração simétrica e assimétrica; (C) os valores das 3 formas de cálculo do coeficiente de atrito na configuração simétrica; e (D) algumas grandezas e o coeficiente de atrito encontrados nos 10 ciclos. Resultados: (A) a maioria dos valores das grandezas e do coeficiente de atrito gerados pelos dois tipos de teste foram diferentes estatisticamente; (B) o braquete de 2º pré-molar apresentou valores de coeficiente de atrito diferentes entre os dois tipos de teste; (C) na configuração simétrica, as variáveis foram estatisticamente significantes na maioria dos casos para as grandezas analisadas e para o coeficiente de atrito; (D) houve diferença entre a configuração simétrica e assimétrica; (E) o coeficiente de atrito baseado nas duas normais e na força de atrito se aproximou mais da realidade clínica e foi sensível à variação da geometria da relação fio-braquete; e (F) os 10 ciclos para lingual foram semelhantes entre si em 70% dos casos e os 10 ciclos para vestibular foram diferentes em 57% dos casos. Conclusões: o teste em 3 pontos com braquetes é diferente do teste de resistência ao deslizamento; a variação das configurações geométricas e da marca de fio-braquete pode influenciar nos valores das grandezas e do coeficiente de atrito cinético; os 10 ciclos para lingual foram mais semelhantes entre si que os 10 ciclos para vestibular. / The main objective of the study is to compare the three-bracket bending test with the resistance to sliding test using a new device that performs simultaneous measurement of coefficient of friction, the forces and moments on the anchor brackets and deactivation force in misaligned bracket, exercised by orthodontic wires. Secondary objectives were to develop the device and compare, in the three-bracket bending test: (i) the influence, on the physical quantities and on the kinetic friction coefficient, of the variation of the symmetry in the inter-bracket distance, of the type of anchor bracket (canine or 2nd premolar), of displacement (3 or 5mm) and misalignment (buccal or lingual) of the central bracket, and of the wire and bracket brand; (ii) the three ways to calculate the coefficient of kinetic friction; (iii) the 10 cycles, for buccal or lingual, to see if they are similar or not. Self-ligating brackets were used (teeth 13, 14 and 15) and wires 0.014 \'\' NiTi and CuNiTi of Aditek and Ormco brands. The resistance to sliding test was conducted on the lingual misalignment, on both displacements and on symmetrical configuration. The three-bracket bending test was held at the lingual and vestibular misalignment, at both displacements and at the symmetrical and asymmetrical configuration. Through ANOVA, were compared, between the two types of tests: (A) the quantities and the coefficient of friction and (B) the coefficient of friction generated only in the second premolar bracket. Using the same statistical test were compared, in three-bracket bending test: (A) in symmetrical configuration, the quantities and the coefficient of friction arising from the variation in the wire and bracket brands, displacement, misalignment and the type of bracket; (B) the quantities and the coefficient of friction generated by the symmetric and asymmetric configuration; (C) the values of the three ways of calculating friction coefficient; and (D) the quantities and the coefficient of friction encountered in 10 cycles. Results: (A) most of the values of the quantities and the coefficient of friction generated by the two types of test were statistically different; (B) the 2nd premolar bracket showed different friction coefficient values between the two types of test; (C) in the symmetrical configuration, the variables were statistically significant in the most of cases for quantities and the friction coefficient; (D) was found difference between symmetric and asymmetric configuration; (E) the friction coefficient based on both normal forces and frictional force was closer to the clinical reality and was sensitive to variations in the geometry of the wire-bracket relationship; and (F) the 10 cycles for lingual were similar in 70% of cases and the 10 cycles for buccal desalignment were different in 57% of cases. Conclusions: The three-bracket bending test is different from the resistance to sliding test; the variation of geometric configurations and wire and bracket brands may influence the values of the quantities and the coefficient of kinetic friction; the 10 cycles for lingual were more similar to each other than the 10 cycles for buccal.
6

Statické řešení dostavby nemocnice v Písku / Static solution of hospital completion in Pisek

Kukla, Radim January 2017 (has links)
In this diploma thesis „Static solution of hospital completion in Pisek“ I study statical solution of one new building of hospital. Statical solution includes the design and dimensioning of reinforced concrete floor structures and peripheral beams. The floor structure consists of point supported reinforced concrete slab. The floor slab is supported by columns and walls. The aim of the project is to desing and evaluate the ultimate limit state of reinforced concrete slab and beams. Also was created 3D computational model to analysis the construction, model was created in software Scia Engineer. To verify the resulting values of internal forces was used to the method of replacement frames. The thesis includes an analysis of internal forces in the structure, while based on different types of soil. Individual values are compared. Finally was made drawings of solved part of the building.

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