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The aim of this thesis is to create a low-cost sensor equipped glove using commercially available components that can be used to obtain position, velocity and acceleration data for individual fingers of a hand within an optical motion capture environment. Tracking the full degrees of freedoms of the hand and finger motions without any hindrances is a challenging task in optical motion capture measurements. Attaching markers on every finger and hand joint makes motion capture systems troublesome due to practical problems such as blind spots and/or obtaining higher derivative motion constraints, such as velocities and accelerations. To alleviate this, we propose a method to capture the hand and finger kinematics with a reduced set of optical markers. Additionally inertial sensors are attached to the fingertips to obtain linear acceleration measurements. For optimal velocity estimation, a Kinematic Kalman Filter (KKF) is implemented and its result is compared to the time derivative of the Motion Capture System measurement. The higher derivative specifications are related to contact and curvature constraints between the fingers and the grasped object and are later used in formulating the synthesis task for the design of robotic fingers and hands. A preliminary prototype device has been developed to obtain position, velocity and acceleration information of each fingertip by incorporating multiple accelerometers into the basic design of reduced marker set.

Concussion and repetitive head impact exposure are significant media, clinical, and research topics. Long-term symptomatic outcomes of sub-injurious head impact exposure have become a topic of concern for professional and youth contact sport athletes alike. Vulnerable populations such as females and pediatric athletes deserve special attention but are understudied. It is known that females tend to be diagnosed with concussions more frequently and incur them at lower peak head kinematic values than their male counterparts. Sex-specific symptom presentation has been demonstrated, but little is known about the effect of athlete perception of head impact exposure or skill level on symptom reporting. Injury biomechanics research has begun to converge on using instrumented mouthguards to monitor head impact exposure in various sports. These devices offer six-degree-of-freedom head kinematic measurements and direct coupling to the measurement point of interest, the skull, by connecting to the upper dentition. However, published post-processing recommendations for these devices differ from one another and manufacturer practices. This lack of commonization makes cross-study comparison difficult. Additionally, the devices are plagued by relative motion artifacts that can leak into reported kinematic signals. The research presented in this dissertation aimed to first address a lack of common post-processing methods available for instrumented mouthguard measurements made with three linear accelerometers and three gyroscopes. We developed an optimal combination of cutoff frequencies for filters applied to these instruments by quantifying the minimal error from a transformation function. We then applied those same methods to instrumented mouthguards, minimizing error based on sport-specific impact duration. Next, mouthguard decoupling artifacts were described in a laboratory study. Decoupling increased kinematic error relative to ground truth measurements from an instrumented headform. We used these data to develop a classification algorithm that found signal features related to mouthguard decoupling while recording an acceleration event in an instrumented mouthguard. We proceeded to salvage impacts with decoupling artifacts. When decoupling was identified, the primary head acceleration signal could be salvaged by wavelet deconstruction. We removed high-frequency content that was representative of decoupling artifacts. We applied these optimized post-processing techniques to instrumented mouthguard data from a group of adolescent female ice hockey players. Their documented head impact exposure was correlated to symptom outcomes and ocular motor evaluation scores. Their sleep and menstrual cycle patterns were included as potential confounding factors. In this sample of athletes, sleep was more strongly associated with symptom presentation than head impact exposure. Ocular motor results showed a possible association with head acceleration exposure severity and menstrual cycle phase, but further study is warranted. Finally, a self-reported association between symptoms and head impact exposure appears to be individual- and skill-level specific, as we saw many variations between individuals of the same sex in what they called a "memorable" head impact. / Doctor of Philosophy / Concussion and repetitive head impact exposure are significant media, clinical, and research topics. Additionally, the long-term outcomes of sub-injurious head impact exposure have become a topic of concern for professional and youth contact sport athletes alike. Vulnerable populations such as females and pediatric athletes deserve special attention but are understudied. Sex-specific symptom presentation has been demonstrated, but little is known about the effect of athlete perception of head impact exposure or skill level on symptom reporting. Instrumented mouthguards are used to monitor head impact exposure in various sports. These devices measure linear and rotational head motion and couple directly to the measurement point of interest, the skull, by connecting to the upper dentition. However, published post-processing recommendations for these devices differ from one another and manufacturer practices. This lack of commonization makes cross-study comparison difficult. Additionally, the devices are plagued by relative motion (decoupling) artifacts that can leak into reported head motion signals. The research presented in this dissertation aimed to first address a lack of common post-processing methods available for instrumented mouthguard measurements made with three linear accelerometers and three gyroscopes. We developed an optimal combination of cutoff frequencies for filters applied to these instruments by quantifying the minimal error from a transformation function. We then applied those same methods to instrumented mouthguards, minimizing error based on sport-specific impact duration. Next, mouthguard decoupling artifacts were described in a laboratory study. Decoupling increased mouthguard error relative to ground truth measurements from an instrumented dummy headform and was direction dependent. We used these data to develop a classification algorithm that found signal features related to mouthguard decoupling while recording an acceleration event in an instrumented mouthguard. We proceeded to salvage impacts with decoupling artifacts through wavelet deconstruction. We applied these optimized post-processing techniques to instrumented mouthguard data from a group of adolescent female ice hockey players. Their documented head impact exposure was correlated to symptom outcomes and eye movement evaluation scores. In this sample of athletes, sleep was more strongly associated with symptom presentation than head impact exposure. Finally, a self-reported association between symptoms and head impact exposure appears to be individual- and skill-level specific, as we saw many variations between individuals of the same sex in what they called a "memorable" head impact.

The evaluation of freeway service quality is crucial work, and thus, transportation professionals have developed numerous measures including traffic volume, speed, and density. However, recent research efforts have indicated that such traditional measures may not fully reflect the quality of roadway service from the perspective of individual drivers, necessitating the development of alternative approaches that complement or replace the current service quality measures. As an alternative approach, the speed variation of a vehicle has been suggested as a promising indicator of traffic flow quality perceived by individual drivers. In particular, acceleration noise, defined by the standard deviation of the acceleration of a vehicle, has been often studied as a measure of the degree of speed variation. However, previous studies have been limited to the experimental level due to the difficulty in collecting high-resolution vehicle speed profiles for computing acceleration noise. In this dissertation, the characteristics of speed variation, measured by acceleration noise, are investigated using the rich set of GPS data collected from the instrumented vehicles driven by the participants of the Commute Atlanta research program. The employment of the real-world vehicle activity data, composed of every second of vehicle operation, renders this research effort unique and provides an opportunity to investigate the various aspects of acceleration noise in the real-world context. The investigation is performed by relating acceleration noise to its three influential factors: traffic conditions, roadway, and driver/vehicles. In addition, a fuzzy inference system-based methodology, combining vehicle speed and acceleration noise from instrumented vehicles, is proposed as an approach to evaluating traffic flow quality.

Gait assessments can help identify individuals at an elevated risk of falling. Gait variability and local dynamic stability (LDS) are considered the most valid measures to assess gait stability and predict gait-related falls. Specifically, LDS of the trunk is most often used to assess gait stability given its important contribution to the centre of mass and the ability to discriminate between fallers and non-fallers using its kinematics. Reliable wearable sensors can be implemented in real-world gait assessments to actively screen for fall risk. Instrumented insoles are an example of unobtrusive wearable technology that can perform accurate gait assessments in real-world settings; however, they have not been validated for gait stability assessments, and cannot directly measure trunk LDS. The purpose of this thesis was to develop a framework to estimate gait stability using instrumented insoles. Fifteen participants were recruited to walk on a treadmill for seven minutes at their preferred walking speed while wearing instrumented insoles and a full-body inertial measurement unit suit. The reliability of foot LDS calculated from instrumented insole data was evaluated against the inertial measurement unit suit using intraclass correlation coefficients. Trunk LDS, measured via the IMU suit, was then predicted by applying linear regressions to the insole-derived metrics. A simple linear regression was used to establish the base amount of variance in trunk LDS that could be explained by foot LDS. Subsequently, a multiple linear regression model consisting of the standard deviation of stride time, standard deviation of double support time, mean single support time, mean yaw variability, and median absolute deviation of yaw variability was used to estimate trunk LDS. Results show that instrumented insoles can reliably measure foot LDS (ICC₃,₁ = 0.860). Moreover, the multiple linear regression explained 47.7% more variance than the simple linear regression (adjusted R² of 0.845 versus 0.368). This thesis demonstrates that instrumented insoles are an appropriate measurement tool for foot stability and that they can be used to predict trunk LDS with good accuracy during gait.

This study evaluates the dynamic interaction between rail vehicles and the track on which they travel. The measurements were analyzed in the time and frequency domain. The effects of external parameters such as the vehicle design, subgrade stiffness, and degree of curvature were analyzed and compared for both the vehicle response and the track geometry data. This study was conducted in close cooperation with the Transportation Technology Center, Inc. (TTCI) in Pueblo, Colorado. The track and vehicle response data was collected on the High Tonnage Loop at TTCI over a span of approximately ten years. For the purpose of this study, TTCI provided this data to the Advanced Vehicle Dynamics Laboratories (AVDL) at Virginia Tech. The analysis of the data was first completed for the vehicle response and track geometry measurements separately. In this manner, the effects of the subgrade stiffness, the degree of curvature, and the vehicle design could be evaluated for each of the measurements. The analysis of the track and rail vehicle response was successfully completed, and the results from this analysis are presented in the following chapters. The analysis showed that the subgrade stiffness had a significant effect on the vertical wheel loads, the track crosslevel, and the track gauge. For an increase in the degree of curvature, the variation of the crosslevel increased. The dynamic response of the vertical and lateral wheel loads showed a significant dependence on the alignment of the rails. Improvements for future studies of the interaction between the track and rail vehicles have been recommended. / Master of Science

Ce travail de thèse a pour but de développer et de caractériser de nouveaux systèmes d'assurance qualité en curiethérapie, à base de sondes dosimétriques en Nitrure de Gallium (GaN). L'étude comprend d'une part la caractérisation et la simulation du transducteur GaN et de la sonde dosimétrique, et d'autre part la mise en œuvre et les tests de 2 systèmes d'assurance qualité.Les propriétés de radioluminescence du transducteur GaN ont été étudiées afin d'optimiser le signal dosimétrique des sondes. La sonde dosimétrique encapsulant un petit volume de cristal GaN a ensuite été caractérisée en vue de son intégration dans des systèmes d'assurance qualité. Des simulations Monte Carlo sur la sonde GaN ont également été effectuées et comparées aux mesures.Pour l'assurance qualité en curiethérapie, nous avons proposé une méthode utilisant plusieurs sondes GaN, pour permettre de déterminer en temps réel les principaux paramètres physiques d'un projecteur de source : la position, le temps de pause et l'activité de la source. Nous avons conçu et réalisé deux prototypes de systèmes d'assurance qualité mettant en œuvre cette méthode : un fantôme instrumenté pour le contrôle prétraitement et un applicateur gynécologique instrumenté pour le contrôle pendant le traitement. Ces deux prototypes ont été testés en conditions cliniques, et leurs principales caractéristiques sont satisfaisantes. Ils répondent aux besoins applicatifs et offrent une perspective intéressante pour de nouveaux outils de contrôle qualité en curiethérapie / This work aims to develop and characterize novel quality assurance systems based on Gallium Nitride (GaN) dosimeter probe for brachytherapy. It includes characterization and simulation studies of the GaN transducer and of the dosimeter probe as well as the implementation and testing of two quality assurance system prototypes.The radioluminescence properties of the GaN transducer have been studied for optimization of the dosimeter response. Characterization studies of dosimeter probes incorporating miniaturized GaN transducers have been carried out in the frame of the quality assurance systems development. Monte Carlo simulations of the GaN probe under irradiation has also been performed and compared with measurements.A method which processes simultaneously the output signals from several GaN probes has been proposed for real time determination of the projector’s physical parameters (dwell position, dwell time and activity of the source). Two quality assurance system prototypes implementing this method have been designed and fabricated: an instrumented phantom for pre-treatment quality assurance and an instrumented gynecological applicator for in vivo quality control. These two prototypes have been tested and evaluated in clinical conditions and their main characteristics are satisfactory. Both systems are in line with the application requirements and offers new perspectives for quality assurance in brachytherapy

[pt] Neste trabalho apresenta-se a avaliação do desempenho de ferramentas de inspeção em linha (ILI) ou pig instrumentado na medição de defeitos causados por corrosão e estudam-se diferentes métodos para o cálculo da confiabilidade estrutural ou cálculo da probabilidade de falha (POF) de um duto corroído, baseada na análise do relatório do pig. O relatório de inspeção do pig é avaliado através de comparações de seus resultados com as medições dos defeitos feitas por ferramentas de referência (medições em campo). Os erros associados a cada sistema de medição podem ser encontrados a partir de métodos estatísticos como os métodos da raiz do erro quadrático médio, dos estimadores de Grubbs, de Thompson e de Jaech. As medições das duas ferramentas são também avaliadas através de testes estatísticos para a linha de tendência e o coeficiente de correlação linear (r). O número mínimo de medições de campo necessárias para verificar o desempenho do pig no dimensionamento dos defeitos de corrosão é determinado pela implementação de um teste baseado na análise seqüencial. Uma vez que o relatório do pig é avaliado e aceito, a POF de um duto corroído é calculada usando os métodos analíticos de primeira ordem (FORM) e propagação de incertezas, e o método de simulação de Monte Carlo. A POF do duto é calculada em função de modelos de pressão de falha onde suas variáveis são definidas como funções de probabilidade (fdp). No caso das dimensões do defeito, a fdp e seus parâmetros estatísticos são obtidos a partir da exatidão do pig. A comparação entre a POF calculada e a POF admissível permite determinar quando será necessário fazer uma nova re-inspeção. Quando a POF calculada atinge um valor maior que a POF admissível, antes de se completar um tempo desejado para a próxima inspeção, o procedimento desenvolvido permite decidir qual o número de reparos que deverá ser feito para que este tempo seja alcançado. / [en] This work presents: i) the assessment of in line inspection (ILI) tools performance in the measurement of defects caused by corrosion; ii) differents methods to calculate structural reliability and probability of failure (POF) of corroded pipeline based in the ILI report. The inspection report of the ILI (or instrumented pig) is compared with the the geometry of defects measured by a reference tool (field measurements) and the erros associated to each measurement system are analyzed and assessed from statistical methods. The statistical analysis emploies methods such as the root mean square error/diffrential, and the Grubbs s, Thompson s and Jaech s estimators. The measurements taken by both tools (pig and field) are compared and analyzed through statistical tests that consider the tendency line and the coefficient of linear correlation (r). The minimum number of field measurements necessary to verify the performance of the ILI in sizing of corrosion defects is determined by the implementation of a test based on the sequential analysis. POF of a pipeline is calculated using three different methods: i) first order reliability methods (FORM); ii) propagation of uncertainties and iii) the method Monte Carlo. The POF of the pipeline is calculated as a function of different failure models whose variables (such as pressure, geometric and material parameters) are defined by their probability functions (pdf). The pdf and statistical parameters of the defect dimensions are determined from the accuracy of the pig measurements. The comparison between calculated and acceptable POF allows the determination of next reinspection period. When the calculated POF exceeds the acceptable POF before completing the amount of time desired for the next inspection, the developed procedure allows to know the number of repairs that must be made to reach the desired time when the next ILI will be carried out.

L’indentation instrumentée est largement utilisée pour la détermination des propriétés mécaniques des matériaux, principalement la dureté et le module d’élasticité. Pour obtenir des données fiables, plusieurs corrections comme la prise en compte du défaut de pointe et la complaisance de l’instrument doivent être apportées dans la méthodologie d’analyse des données de l’essai. Malgré tout, ces corrections ne suffisent plus pour la caractérisation de matériaux fragiles et poreux, qu’ils soient sous une forme massive ou de revêtement. En effet, d’autres sources d’erreurs peuvent provenir de la fragilité de ces matériaux, mais aussi de la représentativité des mesures locales dans le cas des matériaux hétérogènes, ou de l'influence du substrat dans le cas des revêtements. Pour limiter ces effets, l’indenteur Knoop semble être un bon candidat car, à charge équivalente, sa surface de contact est plus grande et la profondeur d’indentation plus faible. Toutefois, par rapport aux indenteurs habituels, le retour élastique du matériau au voisinage de l'empreinte Knoop, qui doit être pris en compte dans les calculs des propriétés, n’est pas bien connu. Ceci constitue donc un frein à son utilisation. C’est pourquoi, nous proposons d’adapter la méthodologie conventionnelle proposée par Oliver et Pharr pour obtenir des résultats fiables par indentation Knoop. Pour atteindre cet objectif, nous analysons d’abord des résultats obtenus par indentation de différents matériaux céramiques denses en comparant les indentations Knoop et Vickers, ce dernier étant utilisé comme référence. Tout d’abord, nous analysons le retour élastique en indentation Knoop et nous montrons qu’il est possible de retrouver les mêmes valeurs qu’en indentation Vickers en intégrant un facteur correctif lié simplement à des grandeurs géométriques de l’empreinte. Cette approche est valable qu’il s’agisse de la détermination du module d’élasticité ou de la dureté. Toutefois, pour cette dernière propriété, il est nécessaire de bien préciser la définition utilisée pour son calcul. Nous en justifions le choix. Ensuite nous appliquons la méthodologie d’analyse ainsi établie pour l’étude de la réponse mécanique des matériaux poreux sous forme massive et de revêtement où non seulement le paramètre de porosité joue un rôle important sur la réponse du matériau, mais aussi son hétérogénéité, sa rugosité et son épaisseur. De manière générale, nous montrons que l’indenteur Knoop présente un intérêt certain par rapport aux indenteurs habituels, tout au moins dans le cas des céramiques. / Instrumented indentation is widely used for the assessment of mechanical properties, mainly hardness and elastic modulus. In order to obtain reliable results, analysis methodology has to refer several corrections, such as tip defect and frame compliance. However, these corrections are insufficient for the characterization of brittle and porous materials, whether bulk or coatings. Not only brittleness but also local surrounding in the case of heterogeneous materials and substrate influence in the case of coatings raise error concerns. To limit these unwanted effects, the Knoop indenter appears to be a favorable candidate because of the larger contact area and lower indentation depth at equivalent loads. However, compared to other commonly used indenters, radial elastic recovery near Knoop indent that has to be taken into account in the analysis methodology, is not well known. This constitutes therefore an obstacle for its use. Thereof, we propose to adapt the conventional methodology proposed by Oliver and Pharr to obtain reliable results with Knoop indentation. To achieve this purpose, we analyze the indentation data of different dense ceramic materials by comparing Knoop and Vickers indentations, this latter being used as a reference. First, we analyze the elastic recovery using Knoop indenter. We show that correlation to Vickers indentation results is possible using a geometric correction factor. This approach is valid for the determination of elastic modulus and hardness. However, for the latter property, it is necessary to specify the definition used for its calculation. The established analysis methodology was applied for studying the mechanical response of porous bulk materials and coatings, with respect to material porosity, roughness and thickness. It was confirmed that Knoop indenter may be favorable compared to the commonly used indenters, at least in the case of ceramics.

Na indústria automobilística há uma grande preocupação em relação ao custo e ao peso das peças utilizadas em projetos e os adesivos vem sendo utilizados para substituir a solda ponto com esta finalidade. Neste contexto o adesivo epóxi estrutural Betamate 1496 vem sendo empregado pela Volkswagen do Brasil S.A para substituição de solda a ponto na fabricação da porta dianteira do veículo Pólo Hatch. O adesivo Betamate 1496 é utilizado na fabricação da carroçaria do veículo Pólo Hatch da Volkswagen do Brasil SA com essa finalidade. O objetivo do presente trabalho é propor e testar uma metodologia para avaliar o estado de cura do adesivo epóxi Betamate 1496 por meio da determinação do seu módulo de elasticidade e de sua dureza, quando este é empregado na fabricação das portas dianteiras do veículo Pólo Hatch. Estas propriedades foram determinadas pela medição das propriedades mecânicas do adesivo em amostras retiradas em seis posições da porta em duas fases de processamento: estado pré-curado, durante a montagem da porta e estado curado, após a cura final na estufa de pintura. O estudo foi realizado através do ensaio de indentação instrumentada, utilizando os procedimentos experimentais propostos por Franco Jr. e colaboradores e Pintaúde e colaboradores na avaliação das propriedades do polímero. O estado de cura do polímero foi avaliado de modo qualitativo também pela técnica de calorimetria diferencial exploratória (Differential Scanning Calormetry). Os resultados obtidos pela metodologia proposta por Franco Jr. e colaboradores apresentaram grande dispersão de valores, provavelmente pelo fato do método propagar erros de arredondamento na aplicação do algoritmo. Conforme observado nos resultados experimentais obtidos pela metodologia proposta por Pintaúde e colaboradores, no estado pré-curado todas as amostras apresentam valores de módulo de elasticidade muito próximos, em torno de 1,0 + 0,1. GPa, independentemente da posição na porta ou do tempo de descarregamento, já no estado curado observa-se uma diferença significativa dos valores de módulo de elasticidade, E, e dureza H dependendo da posição original da amostra na porta, com as amostras retiradas das posições inferiores apresentando E=0,8 + 0,1 GPa, enquanto que as demais apresentam E=1,0+0,1 GPa, os valores de dureza, H, para todas as amostras curadas foi H=0,03 GPa. A analise qualitativa do ensaio térmico pelas as curvas obtidas no ensaio térmico de DSC mostra que as curvas da amostra no estado pré-curado e curado são idênticas, indicando o ciclo de cura do polímero já se completa na fase de montagem da porta, antes mesmo da cura final na estufa de pintura. / Cost and weight reduction are major concerns of the automobilist industry, this leads to the increasing substitution of spot weld by adhesives in the assembling of automobile parts. In this context Volkswagen do Brazil S.A uses the Betamate 1496 structural epoxy adhesive in the manufacture of the chassis of the Polo v. Hatch. The aim of the present work is to suggest and to test a methodology to evaluate the state of cure of this adhesive by means of the determination of its hardness and elastic modulus when used in the manufacture of the front doors of the Polo v. Hatch vehicle. These properties have been determined by the measurement in six samples removed from different positions at the two phases of processing: after assembling of the chassis and cured state, after final cure at painting. The study was carried through instrumented indentation testing, which used the experimental procedures suggested by Franco Jr. and collaborators and Pintaúde and collaborators. The state of cure of polymer was evaluated also in qualitative way by Differential Scanning Calorimetry. The results obtained by the Franco Jr. methodology show great dispersion of values, probable due to the fact that the method propagates rounding errors in the application of the algorithm. The experimental results obtained by the Pintaúde methodology show that, in the state after assembling of the chassis all samples present elastic modulus, E, around 1,0 + 0.1 GPa, independently of the position in the door. In the cured state is observed depending on the sample’s position at the door: samples taken from the bottom of the door shaved E=0,8 + 0,1 GPa, while the remaining showed E= 1,0 + 0,8 GPa. The hardness, H, of the adhesive is constant (H=0,03 GPa) for all samples. The comparison of DSC curves obtained from the incurred and cured samples, showed that they are very similar, suggesting that the cure cycle of the polymer is already completed at assembling stage of the door.