Monitoring an individual’s mobility with a modern smartphone can have a profound impact on rehabilitation in the community. The thesis objective was to develop and evaluate a third-generation Wearable Mobility Monitoring System (WMMS) that uses features from inertial measurement units to categorize activities and determine user changes-of-state in daily living environments. A custom suite of MATLAB® software tools were developed to assess the previous WMMS iteration and aid in third-generation WMMS algorithm construction and evaluation. A rotation matrix was developed to orient smartphone accelerometer components to any three-dimensional reference, to improve accelerometer-based activity identification. A quaternion-based rotation matrix was constructed from an axis-angle pair, produced via algebraic manipulations of acceleration components in the device’s body-fixed reference frame. The third-generation WMMS (WMMS3) evaluation was performed on fifteen able-bodied participants. A BlackBerry Z10 smartphone was placed at a participant’s pelvis, and the device was corrected in orientation. Acceleration due to gravity and applied linear acceleration signals on a BlackBerry Z10 were then used to calculate features that classify activity states through a decision tree classifier. The software tools were then used for offline data manipulation, feature generation, and activity state prediction. Three prediction sets were conducted. The first set considered a “phone orientation independent” mobility assessment of a person’s mobile state. The second set differentiated immobility as sit, stand, or lie. The third prediction set added walking, climbing stairs, and small standing movements classification. Sensitivities, specificities and -Scores for activity categorization and changes-of-state were calculated. The mobile versus immobile prediction set had a sensitivity of 93% and specificity of 97%, while the second prediction set had a sensitivity of 86% and specificity of 97%. For the third prediction set, the sensitivity and specificity decreased to 84% and 95% respectively, which still represented an increase from 56% and 88% found in the previous WMMS. The third-generation WMMS algorithm was shown to perform better than the previous version in both categorization and change-of-state determination, and can be used for rehabilitation purposes where mobility monitoring is required.

Thesis (M.S.)--Brigham Young University. Dept. of Mechanical Engineering, 2007. / Includes bibliographical references (p. 127-130).

Techn., University, Diss., 2003--Berlin.

No description available.

Monitoring an individual’s mobility with a modern smartphone can have a profound impact on rehabilitation in the community. The thesis objective was to develop and evaluate a third-generation Wearable Mobility Monitoring System (WMMS) that uses features from inertial measurement units to categorize activities and determine user changes-of-state in daily living environments. A custom suite of MATLAB® software tools were developed to assess the previous WMMS iteration and aid in third-generation WMMS algorithm construction and evaluation. A rotation matrix was developed to orient smartphone accelerometer components to any three-dimensional reference, to improve accelerometer-based activity identification. A quaternion-based rotation matrix was constructed from an axis-angle pair, produced via algebraic manipulations of acceleration components in the device’s body-fixed reference frame. The third-generation WMMS (WMMS3) evaluation was performed on fifteen able-bodied participants. A BlackBerry Z10 smartphone was placed at a participant’s pelvis, and the device was corrected in orientation. Acceleration due to gravity and applied linear acceleration signals on a BlackBerry Z10 were then used to calculate features that classify activity states through a decision tree classifier. The software tools were then used for offline data manipulation, feature generation, and activity state prediction. Three prediction sets were conducted. The first set considered a “phone orientation independent” mobility assessment of a person’s mobile state. The second set differentiated immobility as sit, stand, or lie. The third prediction set added walking, climbing stairs, and small standing movements classification. Sensitivities, specificities and -Scores for activity categorization and changes-of-state were calculated. The mobile versus immobile prediction set had a sensitivity of 93% and specificity of 97%, while the second prediction set had a sensitivity of 86% and specificity of 97%. For the third prediction set, the sensitivity and specificity decreased to 84% and 95% respectively, which still represented an increase from 56% and 88% found in the previous WMMS. The third-generation WMMS algorithm was shown to perform better than the previous version in both categorization and change-of-state determination, and can be used for rehabilitation purposes where mobility monitoring is required.

The physical behavior of crystalline solids is very closely related to the internal symmetry of the crystal structure. For this reason it is desirable to represent mathematically this symmetry in such a way that the actual physical problems can be handled as they arise. In the case of this thesis the research has been guided by a list of desired properties for such a representation. No claim is made that the list is complete.

The Grassmannian space GC(2, 4) embedded in CP5 as the Klein quadric of twistor theory has a natural interpretation in terms of the geometry of “round” 2-spheres in S4. The incidence of two lines in CP3 corresponds to the contact properties of two 2- spheres, where contact is generalized from tangency to include “half-tangency:” 2-spheres may be in contact at two isolated points. There is a connection between the contact properties of 2-spheres and soliton geometry through the classical Ribaucour and Darboux transformations. The transformation theory of surfaces in S4 is investigated using the recently developed theory of “Discrete Differential Geometry” with results leading to the conclusion that the discrete conformal maps into C of Hertrich-Jeromin, McIntosh, Norman and Pedit may be defined in terms a discrete integrable system employing halftangency in S4.

No description available.

En recherche d’information, les documents sont le plus souvent considérés comme des "sacs-de-mots". Ce modèle ne tient pas compte de la structure temporelle du document et est sensible aux bruits qui peuvent altérer la forme lexicale. Ces bruits peuvent être produits par différentes sources : forme peu contrôlée des messages des sites de micro-blogging, messages vocaux dont la transcription automatique contient des erreurs, variabilités lexicales et grammaticales dans les forums du Web. . . Le travail présenté dans cette thèse s’intéresse au problème de la représentation de documents issus de sources bruitées.La thèse comporte trois parties dans lesquelles différentes représentations des contenus sont proposées. La première partie compare une représentation classique utilisant la fréquence des mots à une représentation de haut-niveau s’appuyant sur un espace de thèmes. Cette abstraction du contenu permet de limiter l’altération de la forme de surface du document bruité en le représentant par un ensemble de caractéristiques de haut-niveau. Nos expériences confirment que cette projection dans un espace de thèmes permet d’améliorer les résultats obtenus sur diverses tâches de recherche d’information en comparaison d’une représentation plus classique utilisant la fréquence des mots.Le problème majeur d’une telle représentation est qu’elle est fondée sur un espace de thèmes dont les paramètres sont choisis empiriquement.La deuxième partie décrit une nouvelle représentation s’appuyant sur des espaces multiples et permettant de résoudre trois problèmes majeurs : la proximité des sujets traités dans le document, le choix difficile des paramètres du modèle de thèmes ainsi que la robustesse de la représentation. Partant de l’idée qu’une seule représentation des contenus ne peut pas capturer l’ensemble des informations utiles, nous proposons d’augmenter le nombre de vues sur un même document. Cette multiplication des vues permet de générer des observations "artificielles" qui contiennent des fragments de l’information utile. Une première expérience a validé cette approche multi-vues de la représentation de textes bruités. Elle a cependant l’inconvénient d’être très volumineuse,redondante, et de contenir une variabilité additionnelle liée à la diversité des vues. Dans un deuxième temps, nous proposons une méthode s’appuyant sur l’analyse factorielle pour fusionner les vues multiples et obtenir une nouvelle représentation robuste,de dimension réduite, ne contenant que la partie "utile" du document tout en réduisant les variabilités "parasites". Lors d’une tâche de catégorisation de conversations,ce processus de compression a confirmé qu’il permettait d’augmenter la robustesse de la représentation du document bruité.Cependant, lors de l’élaboration des espaces de thèmes, le document reste considéré comme un "sac-de-mots" alors que plusieurs études montrent que la position d’un terme au sein du document est importante. Une représentation tenant compte de cette structure temporelle du document est proposée dans la troisième partie. Cette représentation s’appuie sur les nombres hyper-complexes de dimension appelés quaternions. Nos expériences menées sur une tâche de catégorisation ont montré l’efficacité de cette méthode comparativement aux représentations classiques en "sacs-de-mots". / In the Information Retrieval field, documents are usually considered as a "bagof-words". This model does not take into account the temporal structure of thedocument and is sensitive to noises which can alter its lexical form. These noisescan be produced by different sources : uncontrolled form of documents in microbloggingplatforms, automatic transcription of speech documents which are errorprone,lexical and grammatical variabilities in Web forums. . . The work presented inthis thesis addresses issues related to document representations from noisy sources.The thesis consists of three parts in which different representations of content areavailable. The first one compares a classical representation based on a term-frequencyrepresentation to a higher level representation based on a topic space. The abstractionof the document content allows us to limit the alteration of the noisy document byrepresenting its content with a set of high-level features. Our experiments confirm thatmapping a noisy document into a topic space allows us to improve the results obtainedduring different information retrieval tasks compared to a classical approach based onterm frequency. The major problem with such a high-level representation is that it isbased on a space theme whose parameters are chosen empirically.The second part presents a novel representation based on multiple topic spaces thatallow us to solve three main problems : the closeness of the subjects discussed in thedocument, the tricky choice of the "right" values of the topic space parameters and therobustness of the topic-based representation. Based on the idea that a single representationof the contents cannot capture all the relevant information, we propose to increasethe number of views on a single document. This multiplication of views generates "artificial"observations that contain fragments of useful information. The first experimentvalidated the multi-view approach to represent noisy texts. However, it has the disadvantageof being very large and redundant and of containing additional variability associatedwith the diversity of views. In the second step, we propose a method based onfactor analysis to compact the different views and to obtain a new robust representationof low dimension which contains only the informative part of the document whilethe noisy variabilities are compensated. During a dialogue classification task, the compressionprocess confirmed that this compact representation allows us to improve therobustness of noisy document representation.Nonetheless, during the learning process of topic spaces, the document is consideredas a "bag-of-words" while many studies have showed that the word position in a7document is useful. A representation which takes into account the temporal structureof the document based on hyper-complex numbers is proposed in the third part. Thisrepresentation is based on the hyper-complex numbers of dimension four named quaternions.Our experiments on a classification task have showed the effectiveness of theproposed approach compared to a conventional "bag-of-words" representation.

Cette thèse est située dans le contexte des applications de la capture de mouvement humain dont le but est d'inférer la position du corps humain. Les systèmes de capture de mouvement sont des outils "software" et hardware " qui permettent le traitement en temps réel ou en temps différé de données permettant de retrouver le mouvement (position, orientation) d'un objet ou d'un humain dans l'espace. Différents systèmes de capture de mouvement existent sur le marché. Ils diffèrent essentiellement par leur technologie mais nécessitent une adaptation de l'environnement et parfois l'équipement de la personne. Dans cette thèse, on présente un nouveau système de capture de mouvement permettant d'obtenir l'orientation 3D ainsi que l'accélération linéaire d'un mobile à partir des mesures fournies par une minicentrale, développée au sein du CEA-LETI. Cette minicentrale utilise une configuration minimale, à savoir un triaxe magnétomètre et un triaxe accéléromètre. Dans ce travail, on propose différents algorithmes d'estimation de l'attitude et des accélérations recherchées. La rotation est modélisée à l'aide d'un quaternion unitaire. Dans un premier temps, on a considéré le cas d'une seule centrale d'attitude. On s'est intéressé au problème à 6DDL, dont le but est d'estimer l'orientation d'un corps rigide et ses trois accélérations linéaires à partir des mesures fournies par la minicentrale et d'un algorithme d'optimisation. Dans un second temps, on s'est intéressé au cas de la capture de mouvement de chaînes articulées (bras et jambe). A partir d'hypothèses ad-hoc sur les accélérations au niveau des liaisons pivot, on reconstruit le mouvement de la chaîne articulé (orientation) du segment ainsi que l'accélération en des points particuliers du segment. Ces différentes approches ont été validées avec des données simulés et réelles.