Dissertations / Theses: 'Longitudinal force'

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Stahl, Aaron L. "Experimental Measurements of Longitudinal Load Distributions on Friction Stir Weld Pin Tools." Diss., CLICK HERE for online access, 2005. http://contentdm.lib.byu.edu/ETD/image/etd1018.pdf.

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2

Kavanaugh, Ashley A. "Longitudinal Changes in Strength and Explosive Performance Characteristics in NCAA Division I Women’s Volleyball Athletes." Digital Commons @ East Tennessee State University, 2014. https://dc.etsu.edu/etd/2315.

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The purpose of this dissertation was to determine if a periodized strength and conditioning program resulted in long-term adaptations in NCAA Division I women’s volleyball athletes, and if these changes related to the team’s competitive performance. Specifically, this dissertation serves to: 1.) describe the changes in body composition and performance variables of 2 female volleyball athletes over a 4-year collegiate career, 2.) determine the degree and magnitude of change in performance variables after about 1, 2, and 3 years of periodized resistance training, and 3.) infer if volleyball performance characteristics are related to a team’s competitive success. The following are major findings of this dissertation. 1.) Positive changes in vertical jump height, strength, and explosiveness may be possible throughout 4 years of collegiate volleyball training even with increased body mass and percent body fat. Moreover, impaired ability to perform heavy lower-body resistance training exercises due to chronic injury negatively impacts long-term physical performance adaptations over 4 years. 2.) A combination of traditional resistance training exercises and weightlifting variations at various loads, in addition to volleyball practice, appear to be effective at increasing maximal strength by 44% and vertical jump height by 20%-30% in NCAA Division I women’s volleyball athletes after about two and half years of training. Furthermore, these characteristics can be improved in the absence of additional plyometric training outside of normal volleyball-specific practice. 3.) A rating percentage index RPI ranking ratio and unweighted match score ratio appear to be better predictors of overall team competitive season success than a weighted match score ratio. On the contrary, a weighted match score ratio may be better for determining an association between team match performance and volleyball-specific fitness. A considerable amount of research is needed to develop a volleyball-specific performance index that best quantifies team performance and whether or not a measurable association exists between improved fitness characteristics and increased overall team competitive success. The findings of this dissertation provide evidence that analyzing and monitoring volleyball-related performance variables over time can assist the sport performance group in making training based decisions as well as promote the successful development of an athlete.

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3

Castelo, Paula Midori 1978. "Variaveis morfologicas e funcionais do sistema estomatognatico em crianças com oclusão normal e mordida cruzada posterior : estudo longitudinal." [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/287960.

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Orientador: Maria Beatriz Duarte Gavião
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
Made available in DSpace on 2018-08-09T05:11:25Z (GMT). No. of bitstreams: 1 Castelo-Ferrua_PaulaMidori_D.pdf: 3586308 bytes, checksum: 1ca8ad5652e9e92a602e954daadbf136 (MD5) Previous issue date: 2007
Resumo: A manutenção de condições normais da função mastigatória é determinante para o correto crescimento e desenvolvimento de suas estruturas. Assim, três estudos foram desenvolvidos com o objetivo de avaliar crianças na fase de dentição decídua completa e mista inicial com oclusão normal e mordida cruzada posterior funcional. As variáveis estudadas foram: máxima força de mordida, espessura ultra-sonográfica dos músculos masseter e porção anterior do temporal no repouso (RE) e máxima intercuspidação (MI), morfologia e assimetria facial por meio de fotografias frontais padronizadas; correlacionando-as entre si e com o índice de massa corporal (IMC) e buscando determinar as mudanças decorrentes do desenvolvimento da dentição e do tratamento da maloclusão. O primeiro estudo (transversal, n=67) buscou avaliar a influência de hábitos de sucção na presença de mordida cruzada e sua correlação com a força de mordida, morfologia e assimetria facial e variáveis corporais. Observou-se que crianças na fase inicial da dentição mista com mordida cruzada apresentaram menor força de mordida em comparação àquelas com oclusão normal. Na dentição decídua, crianças com mordida cruzada apresentaram faces proporcionalmente mais longas; não foi observada assimetria facial significativa entre os dois tipos de oclusão (teste ¿t¿ Student). Variáveis corporais apresentaram correlação significativa com a força de mordida apenas no grupo de dentição decídua com mordida cruzada (correlação de Pearson). Na dentição decídua, a tendência ao padrão de face longa e a ausência de aleitamento natural por pelo menos seis meses associou-se significativamente à ocorrência de mordida cruzada (regressão logística múltipla). Na dentição mista, a menor força de mordida e ausência de aleitamento natural apresentaram associação positiva com a presença da maloclusão (regressão logística univariada). Já a sucção não-nutritiva mostrou estar relacionada à ocorrência de mordida cruzada em ambas as dentições. ... Observação: O resumo, na íntegra, poderá ser visualizado no texto completo da tese digital
Abstract: Masticatory function is able to influence directly the craniofacial growth and development. In this way, three studies were carried out to evaluate morphological and functional variables of the stomatognatic system in young children with normal occlusion and functional posterior crossbite. Maximum bite force, ultrasonographic thickness of masseter and anterior portion of the temporalis muscles during rest (RE) and maximal intercuspation (MI), and facial morphology and asymmetry by frontal photographs were evaluated, and correlations with body mass index (BMI) were performed to determine morphological and functional changes during normal occlusion development and the correction of the malocclusion. The first one (transversal, n=67) evaluated the influence of sucking habits in the presence of crossbite and its correlation with bite force, facial morphology and asymmetry and body variables. Children in the early mixed dentition with crossbite showed lower bite force magnitude than those with normal occlusion. In the deciduous dentition, children with crossbite showed a long-face tendency, but it was not observed significant facial asymmetry between normal and crossbite groups (t-test). Body variables only presented significant correlation with bite force in the deciduous group with crossbite (Pearson correlation test). In the deciduous dentition, the long-face tendency and the absence of breast-feeding for at least 6 months were significantly associated with crossbite (logistic multiple regression). In the mixed dentition, lower bite force and absence of breast-feeding showed positive association with malocclusion (univariate logistic regression). In both stages of the dentition, nonnutritive sucking habit that persisted up to the age of three years showed to be associated with crossbite (multiple logistic regression). ... Note: The complete abstract is available with the full electronic digital thesis or dissertations
Doutorado
Fisiologia Oral
Doutor em Odontologia

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4

Fileni, Renan Hollanda. "\"Estudo longitudinal da força de mordida em pacientes portadores de próteses parciais fixas sobre implantes osseointegrados: comparação entre áreas dentadas e implantadas\"." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/23/23137/tde-11052007-140243/.

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A proposta deste estudo foi analisar o desenvolvimento da força máxima de mordida em um grupo de pacientes que recebeu próteses parciais fixas sobre implantes (PPFSI) nas regiões de molares, pré-molares até caninos e incisivos antagonizando com dentes naturais e comparar os resultados obtidos com as áreas dentadas do mesmo grupo de pacientes, durante um período de 64 meses (5,3 anos). As forças de mordida foram medidas em cinco regiões da boca: molares em ambos os lados, pré-molares ou caninos em ambos os lados e incisivos; nas áreas de próteses sobre implantes e também nas áreas de dentes naturais. Para tanto, foi usado um transdutor medidor de força de mordida, que tem como princípio de funcionamento uma célula de força colada a um garfo de mordida, amplamente usado na literatura e sempre operado pelo pesquisador. As medições foram feitas imediatamente após a instalação das próteses, 3, 30 e 64 meses depois. Comparando o desenvolvimento das forças de mordida entre as áreas implantadas e de dentes naturais encontra-se já no primeiro controle, após 3 meses de instalação, um aumento das forças de mordida nas próteses sobre implantes instaladas na região de molares que supera as forças desenvolvidas por dentes naturais na mesma região. Para as próteses instaladas na área de incisivos, ao contrário, não foi registrado aumento estatístico destas forças, havendo uma tendência em permanecerem menores quando comparadas às forças desenvolvidas nas mesmas regiões por dentes naturais. Na região de pré-molares ou caninos não houve aumento estatístico de força nas PPFSI. Quando analisadas as áreas dentadas dos pacientes, não houve mudança estatística de força de mordida em nenhuma das regiões durante todo o experimento.
This study proposal was to analyse the changes on the maximal bite force on a patients sample who had implant-supported partial fixed prosthesis (FPP) installed and the results were compared to the ones obtained from the dentate areas on the same sample. Sixteen patients were followed for sixty-four months (5.3 years) and the bite forces were measured on the mouth regions which the prosthesis were installed (molars and premolars up to canines and incisors regions). This measured occurred on five regions of the mouth: both side molars, pre-molars or canines and incisives; either on the places it had a implant as well as on the natural teeth area. In order to do that, it was used as a measuring device, a largely used apparatus which consisted of a biting fork provided with a strain gauge. The bite forces recordings were made at the time of prosthesis installation, after 3, 30 and 64 months thereafter. It was found a bite force increase in the initial period of 3 months after the prosthesis installation in the area of FPP in the molar regions. In this period the bite forces became higher than in dentate situation in the same region and it manteined on this level until the final of the experiment. Comparing the bite straight development between the implanted areas and the natural teeth areas, we found a bite force increased on the prostheses installed over the molars region that overcome the straight development for natural teeth on the same area. On the other hand, for the prostheses installed on the incisive areas, we had not found a statistical straight increased. Actually, it was a tendency to keep smaller than the straight developed on the same regions by natural teeth. On premolars regions or canines, there was not a straight statistical increased on PPFSI. When we analyze the patients? teeth areas, there was not a statistical bite increase on any of the premolars or canines regions during the entire experiment.

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5

Widarda, Dina Rubiana. "Longitudinal forces in continuously welded rails due to nonlinear track-bridge interaction for loading sequences." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2009. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1238081328011-05497.

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The use of continuously welded rails (CWR) governs the longitudinal stress caused by seasonal temperature changes, bending of supporting structure and braking/accelerating due to passing trains. Those three loads have been regulated in Eurocode1 and accomplished by the national codes like DIN Fb-101 in Germany. An additional loading case identified and treated in this thesis is the load due to a change of the coupling stiffness in longitudinal direction between the track and bridge. This additional load occurs as a consequence of the employment of a nonlinear stiffness law which increases the restoring force by a factor of 3 when the situation of the track changes from ‘unloaded’ to ‘loaded’ due to a passing train. This particular phenomenon has not been mentioned in the codes so far though it is a natural consequence of fundamental conditions in those codes. For CWR the longitudinal coupling between the rail and bridge plays an important role. This coupling interface is created either by a ballast, for a ballasted track, or by a fastening system in the case of slab track. The deformation state of the coupling interface characterizes the behaviour of the system, whether elastic or plastic. Therefore, the nonlinear behaviour is valid for the system. To accommodate the nonlinear nature, a sequential loading analysis is used, taking into account the loading history. As the change situation due to a passing train happens in a short time, the influence of the mass acceleration should be taken into account in the system’s equilibrium. This aspect is investigated by treating the dynamic load as an impulse-like load. However, a realistic load needs some time to affect the whole bridge, thus the continuous change of stiffness is used to simulate the dynamic analysis. There is a lack of information on determining the value of coupling stiffness in longitudinal direction caused by a passing train. Therefore, it is important to evaluate the coupling stiffness from field measurements in order to find reliable values. The implementation of the load onto several typical bridges shows that the change of the coupling stiffness increases the stresses and it should not be neglected. The evaluation of the load due to a change of the coupling stiffness accompanied by bending of the supporting structure gives satisfactory results by using the static analysis only. Thus, a dynamic analysis can be avoided. Multiple cycles of passing trains occurring after seasonal temperature change indicate a significant increase of elastic parts along the track-bridge coupling interface and a decrease in stresses in the rails. Thus the danger of deterioration is reduced significantly
Die Verwendung von durchgehend geschweißten Schienen auf Brücken führt zu zusätzlichen Längsspannungen infolge der Lastfälle jahreszeitliche Temperaturänderung, Brückendurchbiegung und Bremsen/Anfahren. Diese drei Lasten sind durch den Eurocode 1 vorgegeben und in die nationale deutsche Norm DIN Fb-101 integriert. In dieser Arbeit wird erstmals ein weiterer Lastfall identifiziert und behandelt, der durch den Wechsel der Koppelsteifigkeit in Längsrichtung zwischen Gleis und Tragwerk bei der Zugüberfahrt begründet wird. Dieser Lastfall wird hier mit „Ruck“ bezeichnet und ist eine zwangsläufige Konsequenz des nichtlinearen Längsverschiebewiderstandes, wie er im EC 1 und im DIN Fb-101 vorgegeben ist. Dennoch wurden die Auswirkungen auf das Systemverhalten bisher nicht untersucht. Bei einem Wechsel vom unbelasteten Gleis zum belasteten Gleis während einer Zugüberfahrt erhöht sich zum Beispiel der Längsverschiebewiderstand für ein Schottergleis um den Faktor 3! Die dadurch bedingte Veränderung des Zusammenwirkens zwischen Gleis und Tragwerk führt zu einer Veränderung des Systemzustandes und damit zu veränderten Schienenspannungen. Für durchgehend geschweißte Schienen spielt die Längskopplung zwischen Schiene und Brücke eine wesentliche Rolle. Beim Schottergleis wird sie dargestellt durch die Einbettung des Gleisrostes im Schotterbett im Zusammenwirken mit der Schienenbefestigung. Bei der festen Fahrbahn durch das Befestigungssystem. Für kleine Deformationen ist die Koppelsteifigkeit proportional zur Relativverschiebung zwischen Gleis und Brücke. Darüberhinaus geht das linear elastische Verhalten in ein quasi plastisches Verhalten mit konstanter Koppelkraft über. Folgerichtig ist die Behandlung einer Lastenfolge nur in inkrementeller Weise unter Einbeziehung der Verformungsgeschichte mechanisch korrekt. Die Lastfälle Bremsen/Anfahren, Brückendurchbiegung und Ruck ereignen sich nur während der Zugüberfahrt; also in relativ kurzer Zeit, dann allerdings mit einem erheblichen Lastgradienten. Somit stellt sich die Frage nach dem Einfluss der Massenbeschleunigungen, die in dieser Arbeit geklärt wird. Die im Fachbericht genanntenWerte für den Längsverschiebewiderstand des belasteten Gleises basieren auf einer relativ geringen Datenmenge. Aus diesem Grund werden die Messdaten einer umfangreichen Feldmessung mit Zugüberfahrten zu Aussagen über den Längsverschiebewiederstand herangezogen und die Problematik derartiger Messungen beleuchtet. Die unterschiedlichen Modellierungen des Lastfalls „Ruck“, einmal rein statisch und zum anderen dynamisch, ergeben übereinstimmende Schienenlängsspannungen für die statische und die kontinuierliche dynamische Variante. Somit kann auf die aufwändige dynamische Analyse verzichtet werden. Mehrere Zyklen von Zugüberfahrten im Anschluss an eine jahreszeitliche Temperaturänderung bewirken einen signifikanten Abbau der Durchrutschbereiche, also eine Erhöhung der elastischen Abschnitte in der Koppelfuge zwischen Bauwerk und Gleis verbunden mit einer Abnahme der Schienendruckspannungen. Somit hilft dieser Effekt dem System, der jahreszeitlichen Temperaturänderung zu widerstehen

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6

Widarda, Dina Rubiana. "Longitudinal forces in continuously welded rails due to nonlinear track-bridge interaction for loading sequences." Doctoral thesis, Technische Universität Dresden, 2008. https://tud.qucosa.de/id/qucosa%3A23616.

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The use of continuously welded rails (CWR) governs the longitudinal stress caused by seasonal temperature changes, bending of supporting structure and braking/accelerating due to passing trains. Those three loads have been regulated in Eurocode1 and accomplished by the national codes like DIN Fb-101 in Germany. An additional loading case identified and treated in this thesis is the load due to a change of the coupling stiffness in longitudinal direction between the track and bridge. This additional load occurs as a consequence of the employment of a nonlinear stiffness law which increases the restoring force by a factor of 3 when the situation of the track changes from ‘unloaded’ to ‘loaded’ due to a passing train. This particular phenomenon has not been mentioned in the codes so far though it is a natural consequence of fundamental conditions in those codes. For CWR the longitudinal coupling between the rail and bridge plays an important role. This coupling interface is created either by a ballast, for a ballasted track, or by a fastening system in the case of slab track. The deformation state of the coupling interface characterizes the behaviour of the system, whether elastic or plastic. Therefore, the nonlinear behaviour is valid for the system. To accommodate the nonlinear nature, a sequential loading analysis is used, taking into account the loading history. As the change situation due to a passing train happens in a short time, the influence of the mass acceleration should be taken into account in the system’s equilibrium. This aspect is investigated by treating the dynamic load as an impulse-like load. However, a realistic load needs some time to affect the whole bridge, thus the continuous change of stiffness is used to simulate the dynamic analysis. There is a lack of information on determining the value of coupling stiffness in longitudinal direction caused by a passing train. Therefore, it is important to evaluate the coupling stiffness from field measurements in order to find reliable values. The implementation of the load onto several typical bridges shows that the change of the coupling stiffness increases the stresses and it should not be neglected. The evaluation of the load due to a change of the coupling stiffness accompanied by bending of the supporting structure gives satisfactory results by using the static analysis only. Thus, a dynamic analysis can be avoided. Multiple cycles of passing trains occurring after seasonal temperature change indicate a significant increase of elastic parts along the track-bridge coupling interface and a decrease in stresses in the rails. Thus the danger of deterioration is reduced significantly.
Die Verwendung von durchgehend geschweißten Schienen auf Brücken führt zu zusätzlichen Längsspannungen infolge der Lastfälle jahreszeitliche Temperaturänderung, Brückendurchbiegung und Bremsen/Anfahren. Diese drei Lasten sind durch den Eurocode 1 vorgegeben und in die nationale deutsche Norm DIN Fb-101 integriert. In dieser Arbeit wird erstmals ein weiterer Lastfall identifiziert und behandelt, der durch den Wechsel der Koppelsteifigkeit in Längsrichtung zwischen Gleis und Tragwerk bei der Zugüberfahrt begründet wird. Dieser Lastfall wird hier mit „Ruck“ bezeichnet und ist eine zwangsläufige Konsequenz des nichtlinearen Längsverschiebewiderstandes, wie er im EC 1 und im DIN Fb-101 vorgegeben ist. Dennoch wurden die Auswirkungen auf das Systemverhalten bisher nicht untersucht. Bei einem Wechsel vom unbelasteten Gleis zum belasteten Gleis während einer Zugüberfahrt erhöht sich zum Beispiel der Längsverschiebewiderstand für ein Schottergleis um den Faktor 3! Die dadurch bedingte Veränderung des Zusammenwirkens zwischen Gleis und Tragwerk führt zu einer Veränderung des Systemzustandes und damit zu veränderten Schienenspannungen. Für durchgehend geschweißte Schienen spielt die Längskopplung zwischen Schiene und Brücke eine wesentliche Rolle. Beim Schottergleis wird sie dargestellt durch die Einbettung des Gleisrostes im Schotterbett im Zusammenwirken mit der Schienenbefestigung. Bei der festen Fahrbahn durch das Befestigungssystem. Für kleine Deformationen ist die Koppelsteifigkeit proportional zur Relativverschiebung zwischen Gleis und Brücke. Darüberhinaus geht das linear elastische Verhalten in ein quasi plastisches Verhalten mit konstanter Koppelkraft über. Folgerichtig ist die Behandlung einer Lastenfolge nur in inkrementeller Weise unter Einbeziehung der Verformungsgeschichte mechanisch korrekt. Die Lastfälle Bremsen/Anfahren, Brückendurchbiegung und Ruck ereignen sich nur während der Zugüberfahrt; also in relativ kurzer Zeit, dann allerdings mit einem erheblichen Lastgradienten. Somit stellt sich die Frage nach dem Einfluss der Massenbeschleunigungen, die in dieser Arbeit geklärt wird. Die im Fachbericht genanntenWerte für den Längsverschiebewiderstand des belasteten Gleises basieren auf einer relativ geringen Datenmenge. Aus diesem Grund werden die Messdaten einer umfangreichen Feldmessung mit Zugüberfahrten zu Aussagen über den Längsverschiebewiederstand herangezogen und die Problematik derartiger Messungen beleuchtet. Die unterschiedlichen Modellierungen des Lastfalls „Ruck“, einmal rein statisch und zum anderen dynamisch, ergeben übereinstimmende Schienenlängsspannungen für die statische und die kontinuierliche dynamische Variante. Somit kann auf die aufwändige dynamische Analyse verzichtet werden. Mehrere Zyklen von Zugüberfahrten im Anschluss an eine jahreszeitliche Temperaturänderung bewirken einen signifikanten Abbau der Durchrutschbereiche, also eine Erhöhung der elastischen Abschnitte in der Koppelfuge zwischen Bauwerk und Gleis verbunden mit einer Abnahme der Schienendruckspannungen. Somit hilft dieser Effekt dem System, der jahreszeitlichen Temperaturänderung zu widerstehen.

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7

Lakhmi, Riadh. "Étude de micropoutres sérigraphiées pour des applications capteurs." Thesis, Bordeaux 1, 2011. http://www.theses.fr/2011BOR14358/document.

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Dans cette thèse, des structures MEMS de type micropoutre ont été conçues pour des applications capteurs. Un procédé de fabrication alternatif au silicium, associant la technique de sérigraphie à l'utilisation d’une couche sacrificielle (SrCO3), a été utilisé pour la réalisation de micropoutres piezoélectriques (PZT, matériau servant à la fois d’actionneur et de transducteur) dans un premier temps. Des tests de détection en phase gazeuse ont été réalisés avec et sans couche sensible avec succès à l’aide du mode de vibration non conventionnel 31-longitudinal. Le toluène a notamment pu être détecté à des concentrations voisines de 20ppm avec une couche sensible PEUT. D’autres espèces telles que l’eau, l’éthanol ou l’hydrogène ont été détectés sans couches sensibles afin de s’affranchir des contraintes liées à celle-ci (vieillissement notamment). Des tests préliminaires de caractérisation en milieu liquide ont également été réalisés avec dans l’optique la détection d’espèces en phase liquide. Par ailleurs, un capteur de force a été conçu et réalisé avec le même procédé de fabrication. Ce dernier est composé d’une micropoutre en matériau diélectrique sur laquelle est intégrée une piezorésistance servant à la transduction du signal associé à la déformation subie par la micropoutre. Des détections de force en mode statique (sans actionneurs) ont permis de caractériser les capteurs, notamment en termes de sensibilité, de gamme de force et de force minimale détectable ou encore de linéarité
The project concerns the conception, fabrication and characterization of cantilever-type MEMS structures for sensors applications. An alternative process to silicon related ones, associating the screen-printing technique to a sacrificial layer (SrCO3), was used to realize piezoelectric cantilevers (PZT material utilized as actuator and transducer) in a first time. Detections in gas phase were performed successfully with and without sensitive layer thanks to the unusual 31-longitudinal vibration mode. Namely, we were able to detect toluene at concentrations as low as 20ppm with a PEUT sensitive layer. Other species like water, ethanol or hydrogen could be detected without sensitive layer in order to get rid of the sensitive layer-related issues (ageing for example). Preliminary characterizations were carried out in liquid phase in a view to perform liquid phase detection. Besides, a cantilever-based force sensor, fabricated thanks to the same fabrication process was designed. This last one integrates a piezoresistor allowing the transduction of the mechanical signal linked to the strain overcome by the microcantilever. Force detections in static mode (without any actuator) permitted the sensors’ characterization. Indeed, their sensitivity, force range, minimal detectable force and linearity were carried out

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Hosseini, SayedMohammad. "A Statistical Approach to Modeling Wheel-Rail Contact Dynamics." Thesis, Virginia Tech, 2021. http://hdl.handle.net/10919/101864.

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The wheel-rail contact mechanics and dynamics that are of great importance to the railroad industry are evaluated by applying statistical methods to the large volume of data that is collected on the VT-FRA state-of-the-art roller rig. The intent is to use the statistical principles to highlight the relative importance of various factors that exist in practice to longitudinal and lateral tractions and to develop parametric models that can be used for predicting traction in conditions beyond those tested on the rig. The experiment-based models are intended to be an alternative to the classical traction-creepage models that have been available for decades. Various experiments are conducted in different settings on the VT-FRA Roller Rig at the Center for Vehicle Systems and Safety at Virginia Tech to study the relationship between the traction forces and the wheel-rail contact variables. The experimental data is used to entertain parametric and non-parametric statistical models that efficiently capture this relationship. The study starts with single regression models and investigates the main effects of wheel load, creepage, and the angle of attack on the longitudinal and lateral traction forces. The assumptions of the classical linear regression model are carefully assessed and, in the case of non-linearities, different transformations are applied to the explanatory variables to find the closest functional form that captures the relationship between the response and the explanatory variables. The analysis is then extended to multiple models in which interaction among the explanatory variables is evaluated using model selection approaches. The developed models are then compared with their non-parametric counterparts, such as support vector regression, in terms of "goodness of fit," out-of-sample performance, and the distribution of predictions.
Master of Science
The interaction between the wheel and rail plays an important role in the dynamic behavior of railway vehicles. The wheel-rail contact has been extensively studied through analytical models, and measuring the contact forces is among the most important outcomes of such models. However, these models typically fall short when it comes to addressing the practical problems at hand. With the development of a high-precision test rig—called the VT-FRA Roller Rig, at the Center for Vehicle Systems and Safety (CVeSS)—there is an increased opportunity to tackle the same problems from an entirely different perspective, i.e. through statistical modeling of experimental data. Various experiments are conducted in different settings that represent railroad operating conditions on the VT-FRA Roller Rig, in order to study the relationship between wheel-rail traction and the variables affecting such forces. The experimental data is used to develop parametric and non-parametric statistical models that efficiently capture this relationship. The study starts with single regression models and investigates the main effects of wheel load, creepage, and the angle of attack on the longitudinal and lateral traction forces. The analysis is then extended to multiple models, and the existence of interactions among the explanatory variables is examined using model selection approaches. The developed models are then compared with their non-parametric counterparts, such as support vector regression, in terms of "goodness of fit," out-of-sample performance, and the distribution of the predictions. The study develops regression models that are able to accurately explain the relationship between traction forces, wheel load, creepage, and the angle of attack.

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Bianchi, Renzo. "Le burnout est-il une forme de dépression ? Approches psychométrique et expérimentale." Thesis, Besançon, 2014. http://www.theses.fr/2014BESA1014.

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La singularité nosologique du burnout vis-à-vis de la dépression n’est pas établie à ce jour. L’objectif de cette thèse de doctorat était d’examiner si burnout et dépression font référence à une même réalité pathologique ou constituent des phénomènes distincts. Nos travaux ont articulé approches dimensionnelles et catégorielles, et études transversales et longitudinales. Empiriquement, ces travaux ont révélé que burnout et dépression sont associés à des symptômes similaires, fluctuent à travers le temps de manière concomitante, et prédisent les mêmes altérations du traitement attentionnel de l’information émotionnelle – tel qu’indexé par l’enregistrement des mouvements oculaires des participants. En parallèle, notre analyse des fondements théoriques de la distinction burnout-dépression a montré que cette dernière est fragile et requiert une clarification. En effet, l’idée selon laquelle le burnout serait « spécifique du contexte de travail » tandis que la dépression serait « indépendante du contexte » n’est pas nosologiquement discriminante en soi. Saisis dans leur ensemble, ces résultats suggèrent que burnout et dépression pourraient couvrir une même réalité pathologique et renvoyer à une même catégorie nosologique, questionnant ainsi la vision actuellement dominante du chevauchement burnout-dépression
To date, the nosological singularity of burnout with respect to depression remains controversial. The aim of this doctoral dissertation was to examine whether burnout and depression refer to a single pathological realm or constitute distinct phenomena. Both dimensional and categorical approaches were adopted, and both cross-sectional and longitudinal designs were used. At an empirical level, our work revealed that burnout and depression are associated with similar symptoms, fluctuate concomitantly over time, and predict the same alterations in the attentional processing of emotional information—as indexed by eye movement recording of participants’ gaze. At a theoretical level, our analyses showed that the grounds of the burnout-depression distinction are fragile and require clarification. Indeed, the idea that burnout is “work-specific” whereas depression is “context-free” is not nosologically discriminating per se. Overall, these results suggest that burnout and depression may cover a single pathological realm and belong to a single nosological category, thus questioning the currently-dominant view of the burnout-depression overlap

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Lakhmi, Riadh. "Etude de micropoutres sérigraphiées pour des applications capteurs." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2011. http://tel.archives-ouvertes.fr/tel-00671386.

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Dans cette thèse, des structures MEMS de type micropoutre ont été conçues pour des applications capteurs. Un procédé de fabrication alternatif au silicium, associant la technique de sérigraphie à l'utilisation d'une couche sacrificielle (SrCO3), a été utilisé pour la réalisation de micropoutres piezoélectriques (PZT, matériau servant à la fois d'actionneur et de transducteur) dans un premier temps. Des tests de détection en phase gazeuse ont été réalisés avec et sans couche sensible avec succès à l'aide du mode de vibration non conventionnel 31-longitudinal. Le toluène a notamment pu être détecté à des concentrations voisines de 20ppm avec une couche sensible PEUT. D'autres espèces telles que l'eau, l'éthanol ou l'hydrogène ont été détectés sans couches sensibles afin de s'affranchir des contraintes liées à celle-ci (vieillissement notamment). Des tests préliminaires de caractérisation en milieu liquide ont également été réalisés avec dans l'optique la détection d'espèces en phase liquide. Par ailleurs, un capteur de force a été conçu et réalisé avec le même procédé de fabrication. Ce dernier est composé d'une micropoutre en matériau diélectrique sur laquelle est intégrée une piezorésistance servant à la transduction du signal associé à la déformation subie par la micropoutre. Des détections de force en mode statique (sans actionneurs) ont permis de caractériser les capteurs, notamment en termes de sensibilité, de gamme de force et de force minimale détectable ou encore de linéarité.

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11

Kim, Mihyun Esther. "A study on pulsation in Runehamar Tunnel fire tests with forced longitudinal ventilation." Link to electronic thesis, 2006. http://www.wpi.edu/Pubs/ETD/Available/etd-100506-112551/.

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Thesis (M.S.) -- Worcester Polytechnic Institute.
Keywords: pulsation; FDS; fire dynamics simulator; oscillation; fluctuation; tunnel fire; forced ventilation. Includes bibliographical references (p.65-66).

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12

Belagod, Trivikram Srinivasan. "ALTERNATING LONGITUDINAL WEDGED COULOMB FORCES MINIMIZE TRANSVERSE TUBE VIBRATIONS THROUGH NON-LINEAR COUPLING." Case Western Reserve University School of Graduate Studies / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=case1250624800.

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13

Lucas, Matthieu. "Influence du sillage de l’installation motrice sur un écoulement d’extrados en configuration de vol de basse vitesse et de forte incidence. Recherche de stratégies de contrôle de l’écoulement." Thesis, Toulouse, ISAE, 2014. http://www.theses.fr/2014ESAE0022/document.

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Lors des phases de vol à basse vitesse et à forte incidence, les effets d’installation motrice sontpilotés par une dynamique tourbillonnaire complexe, instationnaire et en interaction pariétaleforte. Il en résulte en particulier, à la jonction du mât réacteur et de la voilure, l’apparition d’untourbillon de type trombe qui est advecté proche de l’extrados de la voilure. Son interaction avecla couche limite d’extrados a tendance à dégrader les performances aérodynamiques de l’aile etpeut favoriser son décrochage prématuré. Dans ces conditions de vol, l’écoulement autour del’installation motrice est alors régi par la concomitance de décollements locaux, d’interactionstourbillon / couche limite et tourbillon / tourbillon, ainsi que le développement d’instabilitéstelles que l’éclatement tourbillonnaire, le tout en présence d’un gradient de pression défavorableimposé par la voilure.Les travaux menés au cours de cette thèse visent dans un premier temps, par une recherchebibliographique ciblée, à identifier et à analyser les mécanismes tourbillonnaires imposés par laprésence d’une installation motrice proche de voilure afin d’améliorer la compréhension de leurimpact sur les performances aérodynamiques de l’avion. Une attention particulière est portéesur l’analyse des phénomènes d’interaction tourbillon / couche limite qui se produisent sur l’extradosde la voilure.En se basant sur les formes tri-dimensionnelles complexes d’un avion de transport commercial,une simplification géométrique du système Nacelle/Mât/Voilure est proposée. Dans certainesconditions d’angle d’incidence et de dérapage, cette géométrie de référence permet de reproduireune dynamique tourbillonnaire analogue à celle rencontrée sur un avion. Plus spécifiquement,l’accent est porté sur la capacité de cette géométrie à générer un tourbillon de type trombe.Sur cette base, les travaux menés au cours de cette thèse s’intéressent ensuite à caractériserl’influence de modifications locales de la forme du mât sur cette dynamique tourbillonnaire,et notamment sur le tourbillon de type trombe naissant à la jonction mât/voilure. Afin de répondreà ces objectifs, deux approches complémentaires de la mécanique des fluides sont mises enœuvre : d’une part, une approche numérique menée à travers des calculs chimères stationnaireset instationnaires de types RANS et URANS; d’autre part une approche expérimentale conduitepar le biais d’essais en soufflerie mettant en œuvre des visualisations par enduit pariétal ainsique de la PIV bi-composante et stéréoscopique. Une cartographie exhaustive de l’écoulement estainsi obtenue autour de la géométrie de référence et des différents effets de forme. Combiné àun algorithme de suivi des structures cohérentes, les phénomènes tourbillonnaires en interactionpariétale forte sont alors précisément caractérisés. En l’absence de dérapage, l’écoulement autourde la géométrie de référence en incidence est symétrique. Deux structures tourbillonnairescontra-rotatives, générées de part et d’autres des flancs du mât simplifié sont advectés sur l’extradosde la voilure. Cette topologie d’écoulement, partiellement connue de la littérature, a enpartie permis de valider les méthodes expérimentales et numériques mises en place ici. La miseen dérapage de la géométrie en incidence complique l’écoulement et permet de restituer uneorganisation tourbillonnaire analogue à celle rencontrée sur un avion réel, avec en particulier lagénération d’un tourbillon trombe. Le bon accord des résultats expérimentaux et numériques, etla complémentarité des méthodes ont ainsi apporté des éléments de réponse sur les mécanismesà l’origine des décollements locaux d’extrados, qui favorise le décrochage prématuré de la voilure
At low speed/high angle of attack flight conditions, the presence of the powerplant installationunder the wing initiates a complex and unsteady vortical flow field at the nacelle/pylon/wingjunctions. In particular, it results the occurrence of a tornado-like vortex on the pylon crestwhich is advected close to the upper wing. The interaction of this vortical flow with the upperwing boundary layer causes a drop of aircraft performances and can promote a premature stallmechanism. In this flight conditions, the flow field around the engine installation is led by theconcomitance of local boundary layer separations, vortex-wall and vortex-vortex interactions,instabilities like vortex breakdown as well as a strong adverse pressure gradient imposed by thewing.First, thanks to a targeted bibliographic research the present thesis work aims at identifyand analyse the vortical flow field imposed by the presence of the engine installation close tothe wing, in order to have a more comprehensive knowledge of the complex physics. So, it isinitially proposed to simplify the nacelle/pylon/wing configuration of a real transport aircraftby isolating some fundamental mechanisms responsible for this vortical physics, highly designsensitive.In certain conditions of angle of attack and side-slip angle, this simplified geometry isable to recover this particular vortex dynamics interacting with the upper wing boundary layer.Second, based on this previous work, the influence of different local changes of pylon designas well as the influence of the swept wing on the vortex dynamics, and more particularly on thetornado-like vortex are characterised.In order to fulfil these objectives, this thesis work relies on Reynolds Averaged Navier Stokes(RANS) and unsteady Reynolds Averaged Navier Stokes (URANS) computations, oil flow visualizationsand stereoscopic Particle Image Velocimetry (3C-PIV) measurements. An exhaustivecartography of the flow field is then obtained around the simplified geometry and the differentdesign effects. The vortex dynamics thus produced is described in terms of vortex core position,intensity, size, tangential velocity and fluctuating intensity thanks to a vortex trackingapproach. Without side-slip angle, the flow field around the simplified geometry at incidence issymmetric and is characterized by the separation and the longitudinal rolling-up of the cylinderboundary layer into two main counter-rotating vortices distributed on both sides of the cylinder.This vortical topology, partially known in the literature, enables to validate numerical andexperimental methods used here. With a certain side-slip angle, the analysis of the simplifiedgeometry brought to light a more complex vortex dynamics, close to a real aircraft in high-liftflight conditions. This analysis, obtained from the computations and the PIV measurements,highlights the influence of the tornado-like vortex initiated at the pylon/wing junction on theseparation process of the boundary layer near the upper wing leading-edge, which can lead tothe premature stall mechanism

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Plaks, Dmitriy Vital. "Dynamics of longitudinally forced bluff body flames with varying dilatation ratios." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31767.

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Thesis (M. S.)--Aerospace Engineering, Georgia Institute of Technology, 2010.
Committee Chair: Tim Lieuwen; Committee Member: Jeff Jagoda; Committee Member: Suresh Menon. Part of the SMARTech Electronic Thesis and Dissertation Collection.

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Trimeche, Azer. "Décélération Zeeman-Stern Gerlach d'un jet supersonique de particules paramagnétiques par une onde de champ magnétique progressive." Phd thesis, Université Paris Sud - Paris XI, 2013. http://tel.archives-ouvertes.fr/tel-00935655.

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Ce travail porte sur l'étude et la réalisation d'une nouvelle technique de décélération d'un jet supersonique de particules paramagnétiques en utilisant une onde de champ magnétique progressive co-mobile. Cette technique repose sur une méthode de ralentissement basée sur les forces de type Stern Gerlach agissant sur un système paramagnétique en mouvement en présence d'un champ magnétique co-propageant. Cette méthode très innovatrice a l'avantage de pouvoir s'appliquer à une grande palette d'espèces ouvrant ainsi de nouvelles possibilités d'applications. On décrit une approche théorique adaptée qui permet de faire un lien direct entre la théorie, la programmation des paramètres expérimentaux, les résultats obtenus et ce d'une manière systématique, rationnelle et prédictive.Ce mémoire est composé de trois parties. La première porte sur les forces décélératrices et le calcul des différentes forces, de type Stern Gerlach, utilisées dans nos expériences. Les formules établies dans cette partie sont essentielles pour l'interprétation des résultats expérimentaux. La deuxième partie porte sur le dispositif expérimental : le jet supersonique pré-refroidi, la zone d'interaction et la détection. On donne le détail de la réalisation des circuits créant les champs magnétiques nécessaires au guidage et à la décélération du jet. La troisième partie porte sur les résultats des expériences réalisées et leur interprétation directement à partir des équations du mouvement de l'effet Stern Gerlach. Des simulations sont présentées pour étayer les interprétations. On présente les résultats de décélération obtenus récemment sur l'argon et le néon métastables. Ces résultats valident clairement l'importance de l'ajout d'un champ magnétique uniforme qui définit un axe de quantification adiabatique global pour toutes les particules du jet et permet le découplage entre la précession des moments magnétiques et l'action des forces de gradient. Ces résultats mettent en évidence, aussi, l'effet de polarisation du jet qui dépend du sens relatif du champ magnétique uniforme ajouté par rapport à l'onde de champ magnétique progressive.Enfin, la compréhension et le contrôle de la dynamique du piégeage à une vitesse donnée, de l'accélération et de la décélération nécessitent le découplage entre les effets transverses et les effets longitudinaux de l'onde. Ces derniers sont clairement visibles quand le champ magnétique uniforme ajouté vient limiter les effets transverses de l'onde de champ magnétiques progressive. Les perspectives pour ce nouveau décélérateur Zeeman Stern Gerlach sont grandes. Un premier résultat de piégeage du di-azote métastable à 560m/s est présenté et ceci ouvre la voie pour décélérer les molécules paramagnétiques en jet supersonique pulsé. La décélération des radicaux libres et des neutrons est aussi envisageable.

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Dion, John Frederick. "Understanding the forces that affect the market orientation of three diverse teams : a mixed-methods, longitudinal study." Thesis, University of Newcastle upon Tyne, 2014. http://hdl.handle.net/10443/2691.

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Prior research has shown a relationship between market orientation and business performance. Relatively little research, however, has focused on antecedents to market orientation. Additionally, insufficient market orientation research has been conducted at the team level, specifically on new product development and customer teams, the groups closest to new product launches, which are critical to organizational success. There is also insufficient research on how a group’s market orientation might change over time. Lastly, most past studies have used data collected from one or two employees to assess the market orientation of the entire organization. It is not clear how perceptions of market orientation might differ among employees, based on their role within the organization. This research seeks to address these gaps. This research presents the findings from data collected over three years from three teams in the same organization. The teams’ market orientation is viewed through three different lenses: the MKTOR scale developed by Narver and Slater, one-on-one interviews, and network analysis. The research presents a substantive theory that explains the data collected from all three teams and from all three data sources. The data suggests that market orientation is the coordinated effort to gather, disseminate, and respond to information in order to maintain and increase business with the customer, thus supporting an integration of the two primary conceptualizations of market orientation. Throughout the process the team faces ambiguity on many fronts, and the team must deliberately manage this ambiguity in order to be successful. Managing ambiguity, however, is not the same thing as eliminating ambiguity as resource limitations and team size restrict how much ambiguity can be removed. Clarifying communications, including developing a shared understanding of customer targets, serve to remove ambiguity in the team.

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Joyal, Martin. "D'une même voix? Une analyse longitudinale des résultats électoraux des circonscriptions à forte population franco-ontarienne." Thesis, University of Ottawa (Canada), 2007. http://hdl.handle.net/10393/27858.

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La présente thèse a pour objectif d'améliorer notre compréhension des caractéristiques du comportement électoral des Franco-Ontariens. Tout en cherchant à palier à la rareté des études sur le sujet, notre thèse tente de déterminer les conditions présidant à l'existence d'un vote distinctement franco-ontarien aux élections législatives de la province de l'Ontario. Il s'agit d'une analyse longitudinale des résultats électoraux dans les circonscriptions électorales ayant au moins 30 p. cent de francophones dans le cadre des dix élections générales provinciales de 1971 à 2003. La comparaison de ces résultats avec ceux de l'ensemble de la province nous a permis de déceler à plusieurs reprises une volonté politique franco-ontarienne distincte, particulièrement acquise au Parti libéral et au Nouveau parti démocratique dans les régions de l'Est et du Nord-Est de la province. Toutefois, nous n'avons pas été en mesure de démontrer que le vote franco-ontarien était imputable au degré de francité des circonscriptions franco-ontariennes. Ainsi, cette thèse constitue un tremplin pour des études futures en vue d'approfondir cette appréciation des caractéristiques du comportement électoral franco-ontarien.

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18

Essig, Elena. "Les facteurs de développement de la propriété psychologique : une étude longitudinale à l'armée de l'air." Thesis, Tours, 2018. http://www.theses.fr/2018TOUR1001/document.

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Ce travail doctoral s’intéresse au développement de trois types de PP - la propriété psychologique organisationnelle (PPO), la propriété psychologique organisationnelle collective (PPOC) et la propriété psychologique vis-à-vis du groupe (PPGR) - ainsi que leur fluctuation dans le temps dans une organisation publique – l’armée de l’air. Un modèle conceptuel est testé à l’aide de modélisation d’équations structurelles. Les fluctuations des niveaux de la PP sont testées au moyen de tests statistiques de comparaison des variances. Les données quantitatives ont été collectées à trois périodes différentes de la formation militaire auprès de trois cohortes de 100 élèves sous-officiers chacune. Les résultats de la recherche montrent une variabilité des antécédents des trois types de PP selon les étapes de la formation. Ainsi, même si les antécédents de la PPO et la PPOC sont similaires, ils n’évoluent pas de la même manière. Par ailleurs, le sentiment de PPGR est le plus développé et dépend fortement de la cohésion du groupe. Enfin, il existe des fluctuations à la baisse importantes des niveaux de la PP dans le temps
This work investigates the development of three types of PO - Organizational Psychological Ownership (OPO), the Collective Organizational Psychological Ownership (PPOC) and Psychological Ownership towards the group (POGR) and their fluctuation over time in a public organization - the French Air Force. We test a model using structural equation modeling. The fluctuations in PO levels are tested using analysis of variances. The quantitative data were collected from three cohorts of 100 non-commissioned officers each, at three different phases of the military training process. The results of the study show a variability of the antecedents of the three types of PO that depend on the training phases. Even though the OPO and COPO have similar antecedents, they do not evolve in the same way. The feelings of POGR are most developed and depend on the group cohesion. There are significant downward fluctuations in PO levels over time

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19

Trimeche, Azer. "Décélération Zeeman-Stern Gerlach d’un jet supersonique de particules paramagnétiques par une onde de champ magnétique progressive." Thesis, Paris 11, 2013. http://www.theses.fr/2013PA112330/document.

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Ce travail porte sur l’étude et la réalisation d’une nouvelle technique de décélération d’un jet supersonique de particules paramagnétiques en utilisant une onde de champ magnétique progressive co-mobile. Cette technique repose sur une méthode de ralentissement basée sur les forces de type Stern Gerlach agissant sur un système paramagnétique en mouvement en présence d’un champ magnétique co-propageant. Cette méthode très innovatrice a l’avantage de pouvoir s’appliquer à une grande palette d’espèces ouvrant ainsi de nouvelles possibilités d’applications. On décrit une approche théorique adaptée qui permet de faire un lien direct entre la théorie, la programmation des paramètres expérimentaux, les résultats obtenus et ce d’une manière systématique, rationnelle et prédictive.Ce mémoire est composé de trois parties. La première porte sur les forces décélératrices et le calcul des différentes forces, de type Stern Gerlach, utilisées dans nos expériences. Les formules établies dans cette partie sont essentielles pour l’interprétation des résultats expérimentaux. La deuxième partie porte sur le dispositif expérimental : le jet supersonique pré-refroidi, la zone d’interaction et la détection. On donne le détail de la réalisation des circuits créant les champs magnétiques nécessaires au guidage et à la décélération du jet. La troisième partie porte sur les résultats des expériences réalisées et leur interprétation directement à partir des équations du mouvement de l’effet Stern Gerlach. Des simulations sont présentées pour étayer les interprétations. On présente les résultats de décélération obtenus récemment sur l’argon et le néon métastables. Ces résultats valident clairement l’importance de l’ajout d’un champ magnétique uniforme qui définit un axe de quantification adiabatique global pour toutes les particules du jet et permet le découplage entre la précession des moments magnétiques et l’action des forces de gradient. Ces résultats mettent en évidence, aussi, l’effet de polarisation du jet qui dépend du sens relatif du champ magnétique uniforme ajouté par rapport à l’onde de champ magnétique progressive.Enfin, la compréhension et le contrôle de la dynamique du piégeage à une vitesse donnée, de l’accélération et de la décélération nécessitent le découplage entre les effets transverses et les effets longitudinaux de l’onde. Ces derniers sont clairement visibles quand le champ magnétique uniforme ajouté vient limiter les effets transverses de l’onde de champ magnétiques progressive. Les perspectives pour ce nouveau décélérateur Zeeman Stern Gerlach sont grandes. Un premier résultat de piégeage du di-azote métastable à 560m/s est présenté et ceci ouvre la voie pour décélérer les molécules paramagnétiques en jet supersonique pulsé. La décélération des radicaux libres et des neutrons est aussi envisageable
This work focuses on the study and implementation of a new technique of deceleration of a supersonic beam of paramagnetic particles using a co-moving progressive wave of magnetic field. This technique relies on a method of slowing based on Stern-Gerlach forces acting on a paramagnetic system in motion in the presence of a co-propagating magnetic field. This highly innovative approach has the advantage of being applicable to a wide range of species and opens up new opportunities. A suitable theoretical approach is followed, that allows for a direct link between theory, programming of experimental parameters, and experimental results in a systematic, rational and predictive manner.This thesis is composed of three parts. The first concerns the calculation of the various Stern Gerlach forces used in our experiments to decelerate the paramagnetic particles. Formulas established in this section are essential for the interpretation of experimental results. The second part is devoted to the experimental device: the creation of the cooled supersonic beam, interaction zone and detection. A separate chapter is devoted to the detailed description of the different setups of coils used to create the magnetic fields necessary to guide and to decelerate the particles of the beam.The third part is devoted to the experimental results and their direct interpretation using the equations of motion in Stern Gerlach forces. Simulations are presented to embody the interpretations. We present results about the deceleration of metastable argon and neon atoms. These results validate the significance of the addition of a uniform magnetic field defining a global adiabatic quantization axis for all the particles in the beam. This realizes the decoupling between the precession of the magnetic moments and Stern Gerlach forces. The results demonstrate the polarization effect of the beam that depends on the direction of the added uniform magnetic field relative to the progressive wave of the magnetic field.Finally, the understanding and control of the dynamics of trapping at a given speed, acceleration and deceleration require decoupling between the transverse and longitudinal effects of the wave. These effects are clearly visible when the added uniform magnetic field limits the transverse effects of the progressive wave of magnetic field. The outlooks for the new Zeeman Stern Gerlach decelerator are numerous. A first result of trapping di-nitrogen metastable at 560m/s is presented and the road is open to decelerate paramagnetic molecules in pulsed supersonic jet. Deceleration free radicals and neutrons are also possible

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Dahlin, Peter. "Turbulence in Business Networks : A Longitudinal Study of Mergers, Acquisitions and Bankruptcies Involving Swedish IT-companies." Doctoral thesis, Mälardalen University, School of Business, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-432.

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The end of the twentieth centry, and the beginning of the twenty-first, was a revolving period with many mergers, acquisitions and bankruptcies among Swedish IT-companies. Such events are likely to affect more than just the companies directly involved, i.e. the bankrupt and consolidating parties, and this thesis considers the contextual embeddedness of mergers, acquisitions and bankruptcies by studying them in a business network setting.

The primary aim of this thesis is to further the understanding of business network change and its underlying dynamics. A business network is a conceptual description of the interrelatedness of companies, which makes them problematic to describe and understand. This thesis suggests a force-based approach to business network change, which focuses on the forces underlying the change rather than the actual alterations of the business network. The suggested approach emphasizes the change and enables an exploration and description of business network change based on its underlying forces, linked to form a change sequence. The events that occur and the forces they give rise to can be used to describe the character of such business network change sequences.

To enable a study of a change sequence within the Swedish IT-related business network, this thesis will use a technique designed to gather information about events and parts of the business network structure by systematizing data from news items describing mergers, acquisitions and bankruptcies involving Swedish IT-companies during the years 1994-2003. This data structuration technique enables a longitudinal and retrospective study of a business network change sequence. The analysis indicates a high possibility of inter-linkages between mergers, acquisitions and bankruptcies involving Swedish IT-companies, and describes a business network change sequence with high intensity and wide extension, which is the type of business network change with the highest potential impact, here referred to as ‘turbulence in business networks’.

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21

Bracco, Mark Douglas. "A study of the wedge cutting force through longitudinally stiffened plates : an application to grounding resistance of single and double hull ships." Thesis, Monterey, California. Naval Postgraduate School, 1994. http://hdl.handle.net/10945/26279.

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22

Mavros, Georgios. "Tyre models for vehicle handling analysis under steady-state and transient manoeuvres." Thesis, Loughborough University, 2005. https://dspace.lboro.ac.uk/2134/7904.

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The work presented in this thesis is devoted to the study of mechanism of tyre force generation and its influence on handling dynamics of ground vehicles. The main part of the work involves the development of tyre models for use under steady-state and transient operating conditions. The general capability of these models is assessedin a full vehicle simulation environment. The interaction between tyre and vehicle dynamics is critically evaluated and the observed vehicle behaviour is related to the inherent characteristics of different tyre models. In the field of steady-state tyre modelling, two versions of a numerical tyre model are developed. The modelling procedure is carried out in accordance with the viscoelastic properties of rubber, which influence the mechanical properties of the tyre structure and play a significant role in the determination of friction in the tyre contact patch. Whilst the initial simple version of the tyre model assumes a parabolic pressure distribution along the contact, a later more elaborate model employs a numerical method for the calculation of the actual normal pressure distribution. The changes in the pressure distribution as a result of variations in the rolling velocity and normal load influence mainly the levels of self-aligning moment, whilst the force characteristics remain practically unaffected. The adoption of a velocity dependent friction law explains the force generating behaviour of tyres at high sliding velocities. The analysis is extended to the area of transient tyre behaviour with the development of a tyre model appropriate for the study of transient friction force generation within the contact patch. The model incorporates viscoelasticity and inertial contributions, and incorporates a numerical stick-slip law. These characteristics are combined together for the successful simulation of transient friction force generation. The methodologies developed for the modelling of transient friction and steady-state tyre force generation are combined and further extended in order to create a generic transient tyre model. This final model incorporates a discretised flexible viscoelastic belt with inertia and a separate fully-dynamic discretised tread, also with inertia and damping, for the simulation of actual prevailing conditions in the contact patch. The generic tyre model appears to be capable of performing under a variety of operating conditions, including periodic excitations and transient inputs which extend to the non-linear range of tyre behaviour. For the evaluation of the influence of the aforementioned tyre models on the handling responses of a vehicle, a comprehensive vehicle model is developed, appropriate for use in handling simulations. The two versions of the steady-state models and the generic transient model are interfaced with the vehicle model, and the response of the vehicle to a step-steer manoeuvre is compared with that obtained using the Magic Formula tyre model. The comparison between the responses is facilitated by the definition of a new measure, defined as the non-dimensional yaw impulse. It is found that the transience involved in tyre behaviour may largely affect the response of a vehicle to a prescribed input.

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Sedrati, Mouncef. "Morphodynamique transversale et longitudinale de plages à barres intertidales en domaine macrotidal et en conditions de forte agitation : Baie de Wissant, nord de la France." Littoral, 2006. http://www.theses.fr/2006DUNK0169.

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Plusieurs campagnes de mesures hydrodynamiques et topométriques et de transport sédimentaire, menées sur les différentes plages de la Baie de Wissant, Nord de la France, ont été effectuées de 2004 à 2006, et conjointement sur l’année 2004, avec des levées mensuels de profils de plages, dans le but double de mieux comprendre la morphodynamique des plages à barres intertidales dans des sites contrastés (en érosion et en accrétion) et l’évolution globale de la plage intertidale de cette baie. Les données hydrodynamiques ont porté sur une analyse des paramètres de la houle et des courants moyens, et ont été associées aux variations météorologiques (conditions de vent). L’analyse combinée de ces deux éléments a mis en valeur la dominance d’une composante longitudinale qui porte tantôt vers le NE (notamment en condition de temps calme, avec un contrôle par la marée), tantôt vers le SW, en fonction du régime du vent dominant. Les résultats morphométriques apportent des renseignements sur la variation longitudinale de la distribution transversale des barres intertidales sur les plages de la baie, et un éclairage sur le contraste morpho-sédimentaire (érosion-accrétion) au sein de cette baie. Les levés mensuels montrent la formation et la destruction de barres, mais ces processus n’ont pas été mis en évidence par les campagnes expérimentales de courte durée (< 3 semaines en continu), sauf pour des barres de swash dont le développement a été observé lors de conditions de temps calme. La mobilité transversale n’a guère était remarquée lors des suivis de court terme. Plusieurs de ces campagnes expérimentales ont été accompagnées par du temps agité qui a permis de mettre en évidence une intensité parfois exceptionnelle des écoulements longitudinaux. La mobilité longitudinale des barres, mais aussi des chenaux de vidange et leurs figures sédimentaires, était donc le trait marquant de ces expériences sur le site, avec des rythmes de migration des barres qui ont atteint 90 m/jour quand le vent a soufflé latéralement à plus de 19 m s-1, accompagné d’un courant longitudinal frôlant une vitesse de 3 m s-1. La forte mobilité longitudinale des barres intertidales en association avec un transport sédimentaire longitudinal important contribue souvent à des variations morphologiques très significatives au sein du profil, et qui peuvent parfois être mal interprétées comme la signature d’une migration onshore ou offshore des barres. Cette dominance de la composante longitudinale tend à stabiliser la dynamique cross-shore des barres même quand la houle dépasse 1,5 m. Cependant, cette même composante induit un déséquilibre sédimentaire entre le NE et SW de la baie, privant ainsi la partie érodée (SW) de sédiments, et favorisant en parallèle l’accumulation et/ou la stabilité du secteur NE
Several field experiments combining hydrodynamis, topographic, and sediment transport measurements were carried out between 2004 and 2006 on various bar-trough beaches in Wissant Bay, Northern France, with the aim of better understanding the morphodynamics of these systems in a macrotidal setting subject to high-energy longshore flows, and exhibiting erosion and accretion sectors within an overall bay sediment circulation cell. A one-year survey of beach profiles was also carried out on a monthly basis in 2004 and the results analysed in the light of offshore wave data covering the same period. The hydrodynamic data from the short-term field experiments ( < 3 weeks) concerned wave parameters as well as mean longshore and cross-shore currents, and were analysed together with wind data. Under storm conditions, unidirectional flows are either to the NE or to the SW, depending on wind direction. The topographic data highlight various elements of bar distribution, size and movement across the profile, as well as contrasts between the eroding and accreting sectors of the bay. The monthly surveys highlight bar formation and destruction, and cross-shore bar mobility, but these processes were not detected by the short-term field experiments, except for swash bar development on the upper beach during calm conditions. Several experiments werre characterised by high-energy conditions that highlighted the dominant role of longshore currents, which attained peak velocities commonly exceeding 2 m s-1. Longshore bar mobility, as well as longshore migration of intertidal drainage channels and mesoscale bedforms, were the key features highlighted by these short-term surveys. These longshore sediment and bedform movements imparted significant morphological fluctuations captured by the beach profiles, and which may sometimes be mistaken for changes induced by cross-shore processes. These strong longshore flows tend to mitigate cross-shore processes, even when significant wave heights on the beach attain 1. 5 m, but also generate marked longshore sediment budget disequilibrium involved in the chronic erosion of the southwestern sector of the bay, which releases sand for accretion in the northeast

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Wojak, Julien. "Analyse d'images multi-modales TEP-TDM du thorax. Application à l'oncologie : segmentation de tumeurs, d'organes à risque et suivi longitudinal pour la radiothérapie." Phd thesis, Télécom ParisTech, 2010. http://pastel.archives-ouvertes.fr/pastel-00567100.

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En oncologie du thorax, les modalités d'imagerie de tomodensitométrie (TDM) et d'imagerie d'émission de positons (TEP) sont souvent utilisées conjointement, pour le diagnostic ou pour l'élaboration de plans de traitement. En effet, le développement d'appareils d'acquisition combinant ces deux modalités permet leur utilisation conjointe possible en routine clinique sans une difficulté préalable de recalage. Le premier objectif est de proposer des méthodes de segmentation automatiques de tumeurs ou ganglions à l'aide des deux modalités. La modalité TDM étant anatomiquement plus précise les segmentation sont réalisées dans cette modalité en utilisant l'imagerie TEP comme guide pour la localisation de la tumeur. Les organes à risque, devant être protégés des irradiations, nécessitent aussi d'être contourés. Un autre objectif est de proposer des algorithmes permettant leur segmentation. Ils s'appuient sur une connaissance a priori forte des distributions d'intensités des différents organes dans les images TDM et de connaissances a priori de formes des organes à segmenter. Un dernier objectif est de proposer une méthodologie pour la segmentation de tumeurs dans le cadre du suivi longitudinal des patients dans des images préalablement recalées. L'ensemble des méthodes de segmentation a été testé sur différents jeux de données, et lorsque des segmentations manuelles expertes sont disponibles, des résultats quantitatifs sont présentés, montrant l'intérêt des approches proposées et la précision des résultats obtenus.

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Reffay-Pikeroen, Dominique. "Séparation des fonctions de structure transverse et longitudinale par des mesures de coïncidence (e, e'p) sur le noyau de ⁴⁰ Ca." Paris 11, 1987. http://www.theses.fr/1987PA112186.

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Nous avons étudié le courant électromagnétique du nucléon lié dans la du pic quasi-élastique, par des mesures de coïncidence (e,e'p) qui permettent de sélectionner les mécanismes d'éjection d'un proton. Cette étude est grâce à la séparation des fonctions de structure transverse et longitudinale du noyau La réaction (e,e'p) a été réalisée sur le noyau de ⁴⁰ Ca dans une région de moment transféré variant de 330 à 825 MeV/c. Nous avons choisi une gamme d'impulsions du proton dans le noyau variant de 40 à 140 MeV/c et une gamme d'énergie de liaison de 8 à 60 MeV correspondant aux niveaux 1d3/2 1d5/2 2s½ 1s½ 1p3/2 , 1p½ du ³⁹K résiduel prévus par le modèle en couches. Le premier objectif de ces mesures était de vérifier sur un processus exclusif les données sur ce noyau des mesures inclusives avec séparation transverse/longitudinale, données dont l'interprétation théorique pose des problèmes. Plus généralement, le but de ce type d'expérience est de tester la validité de l'approche théorique traditionnelle de la diffusion quasi-élastique : équation de Schrodinger, approximation d'impulsion, choix d'une prescription pour l'effet hors-couche sur le courant nucléonique conservant les facteurs de forme électromagnétique du nucléon libre. La réponse à la première question a été l'observation d'une réduction du rapport longitudinal/transverse des fonctions de structure, réduction cohérente avec l'effet observé dans les expériences inclusives. Pour l'aspect le plus général de la structure électromagnétique du nucléon lié, cette expérience a apporté des données entièrement nouvelles sur le comportement de ses facteurs de forme électrique et magnétique avec le transfert d'impulsion. Ces données ne suggèrent pas de déformation importante du nucléon dans le noyau. Nous avons trouvé pour l'augmentation du rayon magnétique du nucléon dans le noyau une limite supérieure de 4%. Pour le rayon électrique les données restent cependant trop imprécises pour tirer des conclusions définitives sur ce problème
The bound-nucleon current has been investigated in the region of the quasi-elastic peak, with (e,e'p) coincidence measurements where by the one nucleon knock-out process is selected. This study is refined by the measurement of the separate transverse and longitudinal structure functions. The (e,e'p) reaction has been performed on the ⁴⁰ Ca nucleus in a momentum transfer range from 330 to 825 MeV/c. We have chosen a range of proton momenta in the nucleus from 40 to 140 MeV and a missing energy range from 8 to 60 which corresponds to the shells 1d3/2 1d5/2 2s½ 1s½ 1p3/2 , 1p½ of ³⁹K as predicted by the shell model. The first aim of these measurements was to verify, on an exclusive process, the results of the inclusive measurements on this nucleus with transverse/ longitudinal separation, since the inclusive results are presently difficult to interpret. More generally, the aim of this kind of measurements is to test the validity of the traditional theoretical approach to the quasi-elastic scattering Schrëdinger equation, impulse approximation, choice of a prescription for the off shell effect on the nucleonic current keeping the free nucleon electromagnetic form factors. The answer to the first question is the observation of a quenching of the longitudinal/transverse ratio, consistent with the effect observed in the inclusive experiments. Regarding structure of the results about the factors the most general aspect of the study of the electromagnetic bound nucleus, this experiment has brought some entirely new momentum transfer dependence of its electric and magnetic form These results do not suggest any important deformation of the nucleon in the nucleus. We were able to derive an upper limit of 4% for a possible increase of the magnetic radius of the bound proton. Regarding the electric radius, the data still remain too inaccurate to draw final conclusions

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Zghiche, Amina. "Étude de la diffusion quasi-élastique d'électrons sur un noyau lourd ²º⁸Pb : séparation transverse-longitudinale de la section efficace inclusive (e, e')." Paris 11, 1989. http://www.theses.fr/1989PA112285.

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Cette thèse présente les résultats de l'étude des sections efficaces de diffusion profondément inélastique d'électrons sur le noyau ²º⁸Pb. Cette mesure a été effectuée pour des énergies incidentes variant de 140 à 645 MeV pour les angles de diffusion suivants: 35, 60 ,75 ,90 et 143 degrés. La région quasi-élastique a été couverte entièrement par cette mesure. Nous avons séparé la section efficace en deux fonctions de structure transverse et longitudinale par la méthode du diagramme de Rosenbluth en la déconvoluant des effets radiatifs et des effets de distorsion coulombienne, dans la région de moment transféré effectif entre 300 et 650 MeV/c et d'énergie transférée atteignant 350 MeV. La fonction de réponse transverse montre un désaccord avec les prédictions des modèles à particules indépendantes. La contribution des courants d'échange et de l'électroproduction des pions n'a pas été estimée dans le cas du ²º⁸Pb, mais pourrait constituer une explication probable du désaccord observé, puisque les précédentes estimations de ces processus pour les noyaux plus légers ont conduit à un accord avec les résultats expérimentaux. La fonction de réponse longitudinale est aussi en désaccord avec l'estimation des modèles classiques. L'explication de la réduction de la réponse longitudinale en termes de corrélations nucléon-nucléon à l'intérieur du noyau n'est pas satisfaisante puisque l'intensité est uniquement repoussée vers les valeurs élevées de l'énergie transférée, et la règle de somme coulombienne qui en résulte (intégrale du pic quasi-élastique) surestime toujours les valeurs expérimentales. Les corrélations particule-trou calculées dans le cadre de l'Approximation de la Phase Aléatoire ne reproduisent pas non-plus la mesure. Alors que, la modification des propriétés du nucléon lorsqu'il se trouve à l'intérieur du noyau pourrait expliquer le résultat de notre expérience
This thesis presents the results of the deep inelastic scattering cross section study on ²º⁸Pb. The measurement of these cross sections has been performed from 140 MeV to 645 MeV incident energy for these five values of the scattering angle : 35, 60, 75, 90 and 143 degrees. The quasi-elastic region has been entirely recovered by this measurement. We have performed the separation of the measured cross section in one longitudinal and one transverse structure functions with the Rosenbluth Diagram method after performing radiative corrections and corrections from the coulomb distortion effects, between 300 and 650 MeV/c for the effective momentum transfer and up to 350 MeV for the energy transfer. The transverse response function shows a disagreement with the independent particle models predictions. The contribution of the exchange currents and the pion electroproduction processes have not been estimated for ²º⁸Pb, but will make an explanation for the observed disagreement. The estimation of these processes for lighter nuclei has shown an agreement with the experimental results. The longitudinal response function disagrees also with classical models predictions. The explanation of the longitudinal response reduction in terms of nucleon-nucleon correlations is not satisfying since the strength is only pushed towards higher values of the energy transfer, and the resulting coulomb sum rule (integration over the quasi-elastic peak) still overestimating the experimental values. The particle-hole correlations in the Random Phase Approximation framework, do not improve the disagreement with the experiment. While the modification of the nucleon properties in the nuclear medium would be one better explanation of the result of our experiment

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Sjöblom, Arne. "Hälsobokslut! En drivkraft för förändrad verksamhetsstyrning? : En longitudinell studie av tre kommuners försök att minska sjukfrånvaron genom användningen av verksamhetsstyrningsmodeller." Doctoral thesis, Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-10079.

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I början av 2000-talet finansierade regeringen ett projekt, det kommunala hälsobokslutsprojektet, som primärt syftade till att ge erfarenheter och kunskap om olika verksamhetsstyrningsmodellers användbarhet som underlag för det som kallades hälsobokslut. Vidare förväntades projektet ge erfarenheter och kunskap om vilka stödprocesser som var väsentliga för en lyckosam användning av de valda verksamhetsstyrningsmodellerna. Från Näringsdepartementet, som var uppdragsgivare, fanns det även en förväntan att projektet skulle leda till att en gemensam hälsobokslutsmodell skulle kunna användas inom den kommunala sektorn. Underlaget för denna avhandling utgörs av en longitudinell fallstudie där arbetet med hälsobokslutsprojektet har studerats i tre av de kommuner som deltog i projektet. Undersökningen har gjort det möjligt att få fyra forskningsfrågor besvarade: Hur förändrades verksamhetsstyrningen av införandet av hälsobokslut i respektive kommun? Vad initierade denna förändring? Hur genomfördes förändringen av verksamhetsstyrningen? Vad fick förändringen av verksamhetsstyrningen för resultat i de tre kommunerna? Genom att få dessa forskningsfrågor besvarade har det varit möjligt att få kunskap om hur verksamhetsstyrningsmodeller påverkats under en förändringsprocess. Empirin består i huvudsak av fokusgruppsintervjuer vilka har kompletterats med personliga intervjuer och sekundärdata från tre av de kommuner som deltog i hälsobokslutsprojektet. Avhandlingens resultat kan noteras inom fler områden. En organisations syn på sig själv i förhållande till liknande organisationer kan avgöra om ett förändringsarbete kan initieras. Individuella drivkrafter, och speciellt stabiliserande drivkrafter, är viktiga att beakta, och påverka, om ett förändringsarbete ska genomföras. Vidare noteras att institutionella drivkrafter inte enbart kan knytas till existerande strukturer och att individuella drivkrafter inte enbart kan knytas till individers handlingar. Båda typerna av drivkrafter påverkas av och påverka de modaliteter som existerar som förbindelselänk mellan strukturer och handlingar enligt struktureringsteorin. Stödprocesser är viktiga att beakta i anslutning till organisatoriskt lärande och individers handlingar. Särskilt mobiliserande stödprocesser har varit de kommunikations- och motivationsprocesser som synliggjorts med hjälp av de analyser som genomförts.
In the early 2000s the Swedish government financed a health statement project. This project aimed primarily to provide experience and knowledge of the usability of various management control models to function as health statement models. Furthermore, the project was expected to provide experience and knowledge of the supporting processes that was essential for the successful use of the selected management control models. The Ministry of Enterprise, Energy and Communications, which was the principal of the project, expected that the project would lead to the presentation of a common health statement model that could be used within the municipal sector. The basis for this thesis consists of a longitudinal case study in which the health statement project has been studied in three of the municipalities involved in the project. The investigation has made it possible to get four research questions answered: How were the management control systems within the municipalities changed by the introduction of health statements in each municipality? What initiated this change? How was the change in the management control systems achieved? What was the result of the changes of the management control systems within the three municipalities? By answering these research questions it has been possible to gain insight into how management control models have been affected in a change process. The empirical material consists mainly of focus group interviews which have been supplemented by personal interviews and secondary data from three of the municipalities that participated in health statement project. The findings from the research can be observed in several areas. An organization's vision of itself in relation to similar organizations can determine whether a change process can be initiated. Individual forces, and especially stabilizing forces, are important to consider, and influence, if a change program shall be implemented. Institutional forces are linked not only to existing structures and individual drivers are not only linked to individuals' actions. Both types of forces are affected by and affect modalities that exist as interfaces between structures and actions according to the structuring theory. Supporting processes are important to consider in relation to organizational learning and individuals' actions. The communication and motivational processes has been important as mobilizing supporting processes.

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Denis, Dieumet. "Contribution à la modélisation et à la commande de robots mobiles reconfigurables en milieu tout-terrain : application à la stabilité dynamique d'engins agricoles." Thesis, Clermont-Ferrand 2, 2015. http://www.theses.fr/2015CLF22565/document.

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La thématique étudiée dans ce mémoire est axée sur la préservation de la stabilité dynamique de véhicules évoluant en environnement naturel. En effet, la mobilité en milieu tout-terrain est une activité particulièrement pénible et dangereuse en raison de la nature difficile de l'environnement de conduite et de la reconfigurabilité des machines. Le caractère changeant et incertain des interactions rencontrées entre des véhicules à dynamique complexe et variable et leur environnement entraîne régulièrement des risques accrus de renversement et/ou de perte de contrôle (dévalement, dérapage déclenché par une perte soudaine d'adhérence) pour le conducteur. Une forte accidentalité mortelle est, en effet, recensée dans ce secteur, en particulier, dans le milieu agricole ou le renversement de véhicule est classé comme étant la première cause de mortalité au travail. A l'heure actuelle, les approches existantes sur la stabilité d'engins agricoles sont qualifiées à juste titre de passives car elles ne permettent pas d'éviter que les accidents ne se produisent. Par ailleurs, la transposition directe des solutions de sécurité active du secteur de l'automobile (ABS, ESP) s'est révélée inadaptée aux véhicules tout-terrain a cause des hypothèses simplificatrices (routes plates et homogènes, conditions d'adhérence constantes, etc.) dont souffre la conception de ces dispositifs. Ainsi, le développement de systèmes actifs de sécurité prenant en compte les spécificités de la conduite en milieu tout-terrain se révèle être la meilleure voie d'amélioration à suivre. Eu égard à ces circonstances, ce projet se propose d'adresser cette problématique en étudiant des métriques de stabilité pertinentes permettant d'estimer et d'anticiper en temps réel les risques afin de permettre des actions correctives pour la préservation de l'intégrité des machines tout-terrain. Afin de faciliter l'industrialisation du dispositif actif de sécurité conçu, l'une des contraintes sociétales et commerciales de ce projet a été l'utilisation de capteurs compatibles avec le coût des machines visées. L'objectif ambitieux de cette étude a été atteint par différentes voies. En premier lieu, une approche de modélisation multi-échelle a permis de caractériser l'évolution dynamique de véhicules en milieu tout-terrain. Cette approche à dynamique partielle a offert l'avantage de développer des modèles suffisamment précis pour être représentatifs du comportement réel de l'engin mais tout en présentant une structure relativement simple permettant la synthèse d'asservissements performants. Puis, une étude comparative des avantages et des inconvénients des trois grandes familles de métriques répertoriées dans la littérature a permis de mettre en exergue l'intérêt des métriques analytiques à modèle dynamique par rapport aux catégories de critères de stabilité dits statiques et empiriques. Enfin, l'analyse approfondie des métriques dynamiques a facilité le choix de trois indicateurs (Lateral and Longitudinal Load Transfer (LLT), Force Angle Stability Measurement (FASM) et Dynamic Energy Stability Measurement (DESM)) qui sont représentatifs d'un risque imminent de renversement du véhicule. La suite du mémoire s'appuie sur la théorie d'observation pour l'estimation en ligne des variables non directement mesurables en milieu tout-terrain telles que les rigidités de glissement et dérive du pneumatique. Jumelée aux différents modèles dynamiques du véhicule, la synthèse d'observateurs a permis donc d'estimer en temps réel les efforts d'interaction pneumatiques-sol nécessaires à l'évaluation des indicateurs d'instabilité. Le couplage de ces modèles multi-échelles à la théorie d'observation a ainsi constitué un positionnement original à même de briser la complexité de la caractérisation de la stabilité de véhicules à dynamiques complexes et incertaines. (...)
This work is focused on the thematic of the maintenance of the dynamic stability of off-road vehicles. Indeed, driving vehicles in off-road environment remains a dangerous and harsh activity because of the variable and bad grip conditions associated to a large diversity of terrains. Driving difficulties may be also encountered when considering huge machines with possible reconfiguration of their mechanical properties (changes in mass and centre of gravity height for instance). As a consequence, for the sole agriculture sector, several fatal injuries are reported per year in particular due to rollover situations. Passive protections (ROllover Protective Structure - ROPS) are installed on tractors to reduce accident consequences. However, protection capabilities of these structures are very limited and the latter cannot be embedded on bigger machines due to mechanical design limitations. Furthermore, driving assistance systems (such as ESP or ABS) have been deeply studied for on-road vehicles and successfully improve safety. These systems usually assume that the vehicle Center of Gravity (CG) height is low and that the vehicles are operating on smooth and level terrain. Since these assumptions are not satisfied when considering off-road vehicles with a high CG, such devices cannot be applied directly. Consequently, this work proposes to address this research problem by studying relevant stability metrics able to evaluate in real time the rollover risk in order to develop active safety devices dedicated to off-road vehicles. In order to keep a feasible industrialization of the conceived active safety device, the use of compatible sensors with the cost of the machines was one of the major commercial and societal requirements of the project. The ambitious goal of this study was achieved by different routes. First, a multi-scale modeling approach allowed to characterize the dynamic evolution of off-road vehicles. This partial dynamic approach has offered the advantage of developing sufficiently accurate models to be representative of the actual behavior of the machine but having a relatively simple structure for high-performance control systems. Then, a comparative study of the advantages and drawbacks of the three main families of metrics found in the literature has helped to highlight the interest of dynamic stability metrics at the expense to categories of so-called static and empirical stability criteria. Finally, a thorough analysis of dynamic metrics has facilitated the choice of three indicators (Longitudinal and Lateral Load Transfer (LLT), Force Angle Stability Measurement (FASM) and Dynamic Energy Stability Measurement (DESM)) that are representative of an imminent rollover risk. The following of the document is based on the observation theory for estimating online of variables which are not directly measurable in off-road environment such as slip and cornering stiffnesses. Coupled to the dynamic models of the vehicle, the theory of observers has helped therefore to estimate in real time the tire-soil interaction forces which are necessaries for evaluating indicators of instability. The coupling of these multiscale models to the observation theory has formed an original positioning capable to break the complexity of the characterization of the stability of vehicles having complex and uncertain dynamics. (...)

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Pontabry, Julien. "Construction d'atlas en IRM de diffusion : application à l'étude de la maturation cérébrale." Thesis, Strasbourg, 2013. http://www.theses.fr/2013STRAD039/document.

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L’IRM de diffusion (IRMd) est une modalité d’imagerie médicale in vivo qui suscite un intérêt croissant dans la communauté de neuro-imagerie. L’information sur l’intra-structure des tissus cérébraux est apportée en complément des informations de structure issues de l’IRM structurelle (IRMs). Ces modalités d’imagerie ouvrent ainsi une nouvelle voie pour l’analyse de population et notamment pour l’étude de la maturation cérébrale humaine normale in utero. La modélisation et la caractérisation des changements rapides intervenant au cours de la maturation cérébrale est un défi actuel. Dans ce but, ce mémoire de thèse présente une chaîne de traitement complète de la modélisation spatio-temporelle de la population à l’analyse des changements de forme au cours du temps. Les contributions se répartissent sur trois points. Tout d’abord, l’utilisation de filtre à particules étendus aux modèles d’ordre supérieurs pour la tractographie a permis d’extraire des descripteurs plus pertinents chez le foetus, utilisés ensuite pour estimer les transformations géométriques entre images. Ensuite, l’emploi d’une technique de régression non-paramétrique a permis de modéliser l’évolution temporelle moyenne du cerveau foetal sans imposer d’à priori. Enfin, les changements de forme sont mis en évidence au moyen de méthodes d’extraction et de sélection de caractéristiques
Diffusion weighted MRI (dMRI) is an in vivo imaging modality which raises a great interest in the neuro-imaging community. The intra-structural information of cerebral tissues is provided in addition to the morphological information from structural MRI (sMRI). These imaging modalities bring a new path for population studies, especially for the study in utero of the normal humanbrain maturation. The modeling and the characterization of rapid changes in the brain maturation is an actual challenge. For these purposes, this thesis memoir present a complete processing pipeline from the spatio-temporal modeling of the population to the changes analyze against the time. The contributions are about three points. First, the use of high order diffusion models within a particle filtering framework allows to extract more relevant descriptors of the fetal brain, which are then used for image registration. Then, a non-parametric regression technique was used to model the temporal mean evolution of the fetal brain without enforce a prior knowledge. Finally, the shape changes are highlighted using features extraction and selection methods

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30

Cayron, Charles. "Etude théorique et expérimentale de diodes lasers, pour horloges Rubidium et Césium, refroidissement d'atomes et capteurs inertiels." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2011. http://tel.archives-ouvertes.fr/tel-00984686.

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Dans le cadre de l'interaction lumière-atomes, les diodes lasers nécessitent des performances optiques spécifiques : de fortes puissances optiques à une longueur d'onde spécifique (852 nm ou 894 nm pour les atomes de Césium, 780 nm ou 795 nm pour le Rubidium), un fonctionnement monomode transverse et longitudinale du faisceau. Ce mémoire de thèse présente les différentes étapes permettant la fabrication de diodes lasers, émettant à 780 nm, répondant à ces caractéristiques optiques. La spécificité des diodes lasers développé lors de cette thèse est l'absence d'aluminium dans la zone active des lasers, offrant de meilleures performances en termes de fiabilité. Il décrit dans un premier temps les principes du pompage atomique et du refroidissement d'atome afin de déterminer un cahier des charges spécifiques pour les diodes lasers à développer. Il expose ensuite les concepts théoriques permettant de comprendre le fonctionnement d'une diode laser. La caractérisation des diodes lasers développées lors de cette thèse a pu démontrer un fonctionnement monomode transverse jusqu'à des puissances optiques supérieurs à 100 mW pour des lasers Fabry-Pérot. La réalisation de diodes lasers DFB (ayant un réseau de Bragg intégré dans la cavité optique du laser) a montré un fonctionnement monomode fréquentiel jusqu'à 25 mW avec des taux de réjection des modes satellites supérieurs à 45 dB et une largeur de raie de 550 kHz. Enfin, une première étude théorique et expérimentale à partir de diodes lasers émettant à 852 nm a été réalisé afin d'estimer les performances de ces composants dans des horloges à jet thermique utilisant des atomes de Césium.

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Hu, Fu-Kang, and 胡富康. "The Longitudinal Study on Early Chronic Kidney Disease in Air Force." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/32583093942000291647.

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碩士
國防醫學院
公共衛生學研究所
101
Chronic kidney disease (CKD) is one of the predominant epidemic diseases in the world.The increasing prevalence and incidence of CKD also meet to the critical problem in medical cost.Because of the stressful environment, aircrews, who have a high risk of renal dysfunction.It would be a better strategy in preventing the CKD from bad to worse is to diagnose in early stage. In order to achieve this objective, we investigate the prevalence of CKD, and establish the predictable model of disease variation. In this longitudinal study, we elected the 212 Subjects who had participated medical examinations in military hospital since 2004 to 2010, and can be tracked 4 years. By the using aMDRD formula to estimate the glomerular filtration rate, in addition, combine with the NKF-K/DOQI to decide the CKD patients. In these results, the prevalence of CKD was 3.8%, 9.4%, 9.0%, 9.4% for four years. In logistic regression analysis,unusual urobilinogen, ketone, and normal white blood cells in urine and urinary occult blood positive, will increase the risk of CKD. Urinary occult blood positive can predict future risk of CKD. Moreover, GEE model shows that a higher risk of CKD with the examination time, age and experience seniority has a negative effect. In conclusion abnormal urobilinogen, ketone, and normal white blood cells in urine and urinary occult blood positive, might serves as an independent predictor of CKD. In the future, we can focus on not only annual physical examine, but also in simple and accurate examination, such as urinary occult blood. To determine the possibility, then prevent the degeneration of CKD in our aircrews.

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32

Zhong, Xiaoyan. "The Lorentz force and temperature distribution in a longitudinal electromagnetically levitated sample." Thesis, 2000. http://hdl.handle.net/1911/19575.

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Electromagnetic levitation, which can provide rapid heating and melting, homogeneity of melt and minimal specimen contamination, is an important branch of containerless processing. The longitudinal electromagnetic levitator is a new type of levitation device, which was invented recently and has a potential to become a containerless manufacturing processing tool. It has some unique advantages, such as good visual access to the sample, capability to support multiple samples, large loads and cylindrical shape sample availability. In this thesis, a brief review of the history and application of electromagnetic levitation is presented. Then the detailed theoretical analysis coupled with experimental work validating the theoretical models of the longitudinal electromagnetic levitator are presented. First, a new electric current model is introduced, which is more appropriate for the computation of the electromagnetic force field in the levitated specimen. Based on this new model, the essential equations for the electromagnetic field and the lifting force field for a cylindrical sample are derived, the current density distribution and the averaged power in the sample are analyzed. Additionally, both lifting force and lifting capacity for the longitudinal levitator are investigated analytically, and compared with experimental data with good agreement. These theoretical predictions can be used to design longitudinal levitators, to select suitable material for levitation, and to provide the framework for further investigation of materials processing using the longitudinal levitator. In addition, temperature distribution simulation for the sample levitated in the longitudinal electromagnetic levitator is implemented by analytical and numerical ways. Isothermal case, steady state and lumped system are discussed respectively as some special cases. The exact solution and numerical simulation of the temperature distribution for the levitated sample are compared with good agreement. The flow motion within the levitated sample and the numerical simulation of the temperature distribution with flow convection has also been investigated. The results provide important information of the levitation phenomena which are very useful for scientific and engineering applications, especially for materials processing.

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33

Tomblin, Lesley. "Health trends in a Canadian police force : a cross-sectional and longitudinal study /." 2002.

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34

Chen, Wu Po-Chun, and 陳吳柏俊. "Minimum Energy Control of Vehicle Motion by Adaptive H-infinity Method and Longitudinal Tire Force Distribution." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/xybtw8.

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碩士
國立交通大學
電控工程研究所
101
This paper presents a lateral motion control scheme with minimum energy consumption for a front-wheel-steering/front-wheel-driving (FWS/FWD) vehicle using an adaptive H-infinity controller and an optimum longitudinal tire force distribution method. The proposed control system is divided into three layers: the upper controller, the optimum longitudinal tire force distribution and the lower controller. When the driver commands the vehicle, the upper controller finds the optimum weighting among various fixed H-infinity controllers on-line to generate the desired front wheel steering angle and direct yaw moment which allow the vehicle to follow the given reference trajectory with minimum energy loss. Then the optimum longitudinal tire force distribution algorithm determines the minimum longitudinal forces that meet the requirements for direct yaw moment from the upper controller. The lower controller compensates for the nonlinear and uncertain characteristics of the tire dynamics to generate the desired longitudinal tire forces. Finally, simulations are carried out to verify the effectiveness of the proposed control scheme.

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Su, Miao-Ru, and 蘇妙如. "A longitudinal study of labor force participation and intention among middle-aged and older people of different birth cohorts in Taiwan." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/64920493353165197335.

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碩士
國立陽明大學
衛生福利研究所
97
Background Aging population is such a common social phenomenon that many countries faced. By the end of October, 2008, the number of older people had accounted for 10% of total population in Taiwan; the old Age Population Dependency Ratio has also increased simultaneously, which may leads to the shortage of labor force and financial burden of pension system. Recently OECD countries have begun to encourage the middle and old-age people to prolong their time of retirement, so does Taiwan. Retirement and employment of these people has become an important issue. Objective The aims of this study are as following: 1.To compare the labor force participation or intention of re-employment among different birth cohorts of middle and older-aged people. 2.To explore the impact of previous intention of re-employment on labor force participation among different birth cohorts of middle and old-age people. 3.To exam whether the difference among birth cohort in labor force participation or intention of re-employment are the same for middle and old-age people with different economic and health status. Method This study, based on longitudinal panel study design, applied data obtained from “Survey of Health and Living Status of the Middle Aged and Elderly in Taiwan” which had been conducted in 1996, 1999, and 2003 by the Bureau of Health Promotion, Department of Health. The study populations were middle and old-age people in Taiwan. Total number of samples was 2687 which included those between age 50-75 years and older, has participated in all three waves of survey, yet had answered the questions by themselves (without using proxies). The independent variables, the birth cohort, were divided into three groups based on economic development stage of Taiwan. The dependent variables were labor force participation (yes/no) and intentions of re-employment (divided into retirement and re-employment intentions). Generalized Estimating Equation (GEE) was used to control covariates and the effect of autocorrelation among repeated measures. Result 1.Different birth cohorts had significant difference in changes of economic and health status but have no difference in retirement intentions. 2.Different cohorts were different in re-employment intentions, yet the relationship had no difference among people with different economic and health status. 3.Different cohorts were different in labor force participation, this relationship differed among people with different economic and health status 4.Previous re-employment intention was significantly associated with labor force participation. Implication We suggest that the government should put greater effort to enhance the economic security and health status of the middle and old-age people and to advocate life planning after retirement in order to promote their life quality. Besides, policy may be developed aim at the late birth cohort who has high re-employment intentions and to advocate policy of the re-employment after retirement or unemployment. Furthermore, the government could develop new employment pattern, like flexible employment and so on, then through promoting health and safeguarding economical security for the middle-aged and older laborers, to utilize the labor force effectively. Finally, we suggest further research may explore the related factors which influence the intentions or time-variant intention on re-employment.

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Lee, Ting-Yi, and 李庭毅. "Experimental Verification on the Estimation and Control Laws of Longitudinal Tire Forces." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/pw38dz.

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碩士
國立交通大學
電控工程研究所
107
Longitudinal tire forces is an important information for vehicular active safety systems. Due to increasingly demanding requirements for driving safety, more and more vehicle control systems have been developed. Many academic studies rely only on software simulations to verify the performance of vehicle control systems; however, the success of simulation verification does not guarantee that the design specifications are satisfied in the real world because of the tremendously increasing complexity and uncertainty form simulations to full-vehicle tests. Therefore, building an experimental platform is essential to reduce the gap between the software simulation and the real vehicle test. In this thesis, we aimed at experimentally verifying the estimation and control laws of longitudinal tires forces. We design an experimental platform with a single tire which can simulate different tire speeds and vehicle speeds to generate different slip-ratios and longitudinal tire forces. A force sensor is installed to measure the tire forces directly, and a servo motor controls the wheel torque to realize and verify the longitudinal tire force estimation and control laws. The components in the experimental platform, such as the motors and the sensors are cost effective, and the overall platform is less space demanding. It is suitable for the development and testing of various tire force control and estimation systems in the lab.

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Soon, Chin Fhong, K. S. Tee, Mansour Youseffi, and Morgan C. T. Denyer. "Compressive forces of cell induced longitudinal deformation to the liquid crystal surface." 2015. http://hdl.handle.net/10454/9226.

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No
The ability of a cell to contract plays an important role in determining the ability of the cell to migrate, proliferate and associating with other cells. The transduction of the force in soft substrate such as the liquid crystal surface is a method proposed to study the traction forces of single cells. In this work, finite element method was used to study the compressive forces induced by the keratinocyte to the liquid crystal surface via the anchorage of focal contacts. The constitutive finite element model of the liquid crystal-focal contacts was established. The stress and displacement were analyzed using linear static stress analysis for a quiescent cell. The data for lateral displacements obtained from the experiment were provided as inputs to develop the model and verified through the output acquired for both simulation and experiment. The simulation results indicated that the cell compressive stresses were in the range of 14.93 ± 1.9 nN/μm2 per focal contact. Based on the result obtained, it was suggested to model focal contact-liquid crystal interface with a compressive model that can better approximate the mechanism observed

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Widarda, Dina Rubiana [Verfasser]. "Longitudinal forces in continuously welded rails due to nonlinear track-bridge interaction for loading sequences / vorgelegt von Dina Rubiana Widarda." 2009. http://d-nb.info/993934668/34.

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39

Coetzer, C. B. "The development of a new compact model for prediction of forced flow behaviour in longitudinal fin heat sinks with tip bypass." Diss., 2001. http://hdl.handle.net/2263/26228.

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Increasing power dissipation and chip densities in the rapidly evolving electronics cooling industry are causing an ever increasing need for the tools and methods necessary for electronic systems design and optimisation. Modern electronic systems have the capacity to produce significant amounts of heat which, if not removed efficiently, could lead to component failure. The most common technique of heat removal is by making use of a heat spreader, or so¬-called heat sink. These devices are excellent heat conductors with a large surface area to volume ratio, and cooled through either natural or forced convection. Despite the advantages of these devices, there are serious consequences involved in the application of heat sinks. The required size of a heat sink may limit the miniaturisation of a product, while inadequate design, due to a lack of understanding of the flow physics, may lead to premature component failure. It is therefore crucial that an optimal heat sink design is achieved for every particular application. In the past, both heat sink design and optimisation have occurred mostly through experimental characterisation of heat sinks, which was not always particularly successful or accurate. Recent rapid developments in computer technology have led to the availability of various computational fluid dynamics or CFD software packages, with the capability of solving the discretized form of the conservation equations for• mass, momentum, and energy to provide a solution of the flow and heat fields in the domain of interest. This method of using the fundamental flow physics is currently the most complete way to determine the solution to the heat sink design and optimisation problem. It does unfortunately have the drawback of being computationally expensive and excessively time consuming, with commercial software prices being financially restrictive to the average designer. The electronics cooling community has subsequently identified the need for so-called "compact models" to assist in the design of electronic enclosures. Compact models use available empirical relations to solve the flow field around a typical heat sink. Current models require significantly less computational power and time compared to CFD analysis, but have the drawback of reduced accuracy over a wide range of heat sink geometries and Reynolds numbers. This is one of the reasons that compact modelling of heat sinks remain an international research topic today. This study has focused on the CFD modelling of a variety of forced flow longitudinal fin heat sinks with tip clearance. Tip clearance allows the flow to bypass the heat sink and downgrade its thermal performance. The flow bypass phenomenon, general flow behaviour, and pressure loss characteristics were investigated in detail. Thermal modelling of the heat sinks was left for future study. The flow information provided by the CFD analysis was combined with data available from literature to develop an improved compact flow model for use in a variety of practical longitudinal fin heat sinks. The new compact model leads to a 4.6 % improvement in accuracy compared to another leading compact model in the industry, and also provides more localised flow information than was previously available from compact modelling.

Dissertation (M Eng (Mechanical Engineering))--University of Pretoria, 2007.
Mechanical and Aeronautical Engineering
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Ravi, Gurunarayana. "Study of Laminar Flow Forced Convection Heat Transfer Behavior of a Phase Change Material Fluid." 2008. http://hdl.handle.net/1969.1/ETD-TAMU-2008-12-231.

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The heat transfer behavior of phase change material fluid under laminar flow conditions in circular tubes and internally longitudinal finned tubes are presented in this study. Two types of boundary conditions, including uniform axial heat flux with constant peripheral temperature and uniform axial and peripheral temperature, were considered in the case of circular tubes. An effective specific heat technique was used to model the phase change process assuming a hydrodynamically fully-developed flow at the entrance of the tube. Results were also obtained for the phase change process under hydro dynamically and thermally fully developed conditions. In case of a smooth circular tube with phase change material (PCM) fluid, results of Nusselt number were obtained by varying the bulk Stefan number. The Nusselt number results were found to be strongly dependent on the Stefan number. In the case of a finned tube two types of boundary conditions were studied. The first boundary condition had a uniform axial heat flux along the axis of the tube with a variable temperature on the peripheral surface of the tube. The second boundary condition had a constant temperature on the outer surface of the tube. The effective specific heat technique was again implemented to analyze the phase change process under both the boundary conditions. The Nusselt number was determined for a tube with two fins with different fin height ratios and fin thermal conductivity values. It was determined that the Nusselt number was strongly dependent on the Stefan number, fin thermal conductivity value, and height of the fins. It was also observed that for a constant heat axial flux boundary condition with peripherally varying temperature, the phase change slurry with the internally finned tube performed better than the one without fins. A similar trend was observed during the phase change process with internal fins under the constant wall temperature boundary condition.

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Dissertations / Theses on the topic 'Longitudinal force'

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