Ce travail de thèse traite du développement d'une méthode de télédiagnostique de l'état de santé des suspensions des trains à grande vitesse à partir de mesures de la réponse dynamique du train en circulation par des accéléromètres embarqués. Un train en circulation est un système dynamique dont l'excitation provient des irrégularités de la géométrie de la voie ferrée. Ses éléments de suspension jouent un rôle fondamental de sécurité et de confort. La réponse dynamique du train étant dépendante des caractéristiques mécaniques des éléments de suspension, il est possible d'obtenir en inverse des informations sur l'état de ces éléments à partir de mesures accélérométriques embarquées. Connaître l'état de santé réel des suspensions permettrait d'améliorer la maintenance des trains. D’un point de vue mathématique, la méthode de télédiagnostique proposée consiste à résoudre un problème statistique inverse. Elle s'appuie sur un modèle numérique de dynamique ferroviaire et prend en compte l'incertitude de modèle ainsi que les erreurs de mesures. Les paramètres mécaniques associés aux éléments de suspension sont identifiés par calibration Bayésienne à partir de mesures simultanées des entrées (les irrégularités de la géométrie de la voie) et sorties (la réponse dynamique du train) du système. La calibration Bayésienne classique implique le calcul de la fonction de vraisemblance à partir du modèle stochastique de réponse et des données expérimentales. Le modèle numérique étant numériquement coûteux d'une part, ses entrées et sorties étant fonctionnelles d'autre part, une méthode de calibration Bayésienne originale est proposée. Elle utilise un métamodèle par processus Gaussien de la fonction de vraisemblance. Cette thèse présente comment un métamodèle aléatoire peut être utilisé pour estimer la loi de probabilité des paramètres du modèle. La méthode proposée permet la prise en compte du nouveau type d'incertitude induit par l'utilisation d'un métamodèle. Cette prise en compte est nécessaire pour une estimation correcte de la précision de la calibration. La nouvelle méthode de calibration Bayésienne a été testée sur le cas applicatif ferroviaire, et a produit des résultats concluants. La validation a été faite par expériences numériques. Par ailleurs, l'évolution à long terme des paramètres mécaniques de suspensions a été étudiée à partir de mesures réelles de la réponse dynamique du train / The work presented here deals with the development of a health-state monitoring method for high-speed train suspensions using in-service measurements of the train dynamical response by embedded acceleration sensors. A rolling train is a dynamical system excited by the track-geometry irregularities. The suspension elements play a key role for the ride safety and comfort. The train dynamical response being dependent on the suspensions mechanical characteristics, information about the suspensions state can be inferred from acceleration measurements in the train by embedded sensors. This information about the actual suspensions state would allow for providing a more efficient train maintenance. Mathematically, the proposed monitoring solution consists in solving a statistical inverse problem. It is based on a train-dynamics computational model, and takes into account the model uncertainty and the measurement errors. A Bayesian calibration approach is adopted to identify the probability distribution of the mechanical parameters of the suspension elements from joint measurements of the system input (the track-geometry irregularities) and output (the train dynamical response).Classical Bayesian calibration implies the computation of the likelihood function using the stochastic model of the system output and experimental data. To cope with the fact that each run of the computational model is numerically expensive, and because of the functional nature of the system input and output, a novel Bayesian calibration method using a Gaussian-process surrogate model of the likelihood function is proposed. This thesis presents how such a random surrogate model can be used to estimate the probability distribution of the model parameters. The proposed method allows for taking into account the new type of uncertainty induced by the use of a surrogate model, which is necessary to correctly assess the calibration accuracy. The novel Bayesian calibration method has been tested on the railway application and has achieved conclusive results. Numerical experiments were used for validation. The long-term evolution of the suspension mechanical parameters has been studied using actual measurements of the train dynamical response

<p>The aim with this thesis was to study cardiovascular disease and hypertension, use of drugs and health from an epidemiological perspective. Various methods - self-rated health (SRH), health related quality of life (HRQL) - the 36-item short form questionnaire (SF-36) - and health utility measurements - the rating scale (RS) and the time-trade off (TTO) methods - were employed.</p><p>Data from the Swedish Adoption/Twin Study of Aging (SATSA) in 1984, 1987, 1990, and 1993 as well as a general population survey conducted in Uppsala County in 1995 were used.</p><p>Persons who have cardiovascular disease, both with and without drug treatment, were found to have a lower SRH as compared to others in the population. Longitudinal analyses showed that SRH was relatively stable over time among persons with cardiovascular disease. Both having a low SRH and having cardiovascular disease were associated with a higher mortality rate.</p><p>Hypertensives were found to have a lower HRQL than do others in the general population as measured by the SF-36. The lowest scoring was found in the general health perception scale (GH), whereas role emotional (RE) and mental health (MH) were the scales least affected by hypertension.</p><p>Nearly 20 percent of the antihypertensive drug users reported side effects.The pattern of side effects was similar to that reported in clinical trials. Both hypertension itself and the drug treatment were found to have an impact on the patient's health-state utility as measured by the RS. Comparative analyses showed that health utilities and psychometric quality-of-life instruments were only moderately correlated among hypertensives. </p><p>The results also showed that inequalities in HRQL were present with respect to several sociodemographic factors. </p><p>In summary, this thesis revealed that persons with cardiovascular disease and/or with hypertension experience poorer health than others in the population. The poor health may be caused both by the disease and/or the drug treatment. The results in this thesis also suggested that special attention and care should be directed to persons with cardiovascular disease and/or hypertension reporting ill health. This especially is important given that low HRQL can be a riskfactor for subsequent cardiovascular events or complications which in turn might result in higher mortality rate.</p>

The aim with this thesis was to study cardiovascular disease and hypertension, use of drugs and health from an epidemiological perspective. Various methods - self-rated health (SRH), health related quality of life (HRQL) - the 36-item short form questionnaire (SF-36) - and health utility measurements - the rating scale (RS) and the time-trade off (TTO) methods - were employed. Data from the Swedish Adoption/Twin Study of Aging (SATSA) in 1984, 1987, 1990, and 1993 as well as a general population survey conducted in Uppsala County in 1995 were used. Persons who have cardiovascular disease, both with and without drug treatment, were found to have a lower SRH as compared to others in the population. Longitudinal analyses showed that SRH was relatively stable over time among persons with cardiovascular disease. Both having a low SRH and having cardiovascular disease were associated with a higher mortality rate. Hypertensives were found to have a lower HRQL than do others in the general population as measured by the SF-36. The lowest scoring was found in the general health perception scale (GH), whereas role emotional (RE) and mental health (MH) were the scales least affected by hypertension. Nearly 20 percent of the antihypertensive drug users reported side effects.The pattern of side effects was similar to that reported in clinical trials. Both hypertension itself and the drug treatment were found to have an impact on the patient's health-state utility as measured by the RS. Comparative analyses showed that health utilities and psychometric quality-of-life instruments were only moderately correlated among hypertensives. The results also showed that inequalities in HRQL were present with respect to several sociodemographic factors. In summary, this thesis revealed that persons with cardiovascular disease and/or with hypertension experience poorer health than others in the population. The poor health may be caused both by the disease and/or the drug treatment. The results in this thesis also suggested that special attention and care should be directed to persons with cardiovascular disease and/or hypertension reporting ill health. This especially is important given that low HRQL can be a riskfactor for subsequent cardiovascular events or complications which in turn might result in higher mortality rate.

<p>One must consider cost effectiveness when deciding how resources within the health sector should be distributed. Quality adjusted life years (QALYs) are used to measure the value of different medical treatments. QALY is based on utility maximization theory, which suggests that a QALY is always a QALY regardless of who receives it. Therefore, a produced QALY is worth the same regardless of the age or the initial health of the patient. Previous research has shown that these assumptions do not seem to fit the real preferences of individuals. Further, there are different methods of acquiring QALYs that give different outcomes. Two of these methods are Time Trade Off (TTO), in which respondents are confronted with a valuation of health change in time, and Person Trade Off (PTO), where respondents are confronted with a valuation in persons. Arguably, PTO is the preferred method that takes greater account of how individuals wish to allocate the resources of the society. From a distribution perspective focusing on age and initial health status, this paper aims to empirically identify the differences between TTO and PTO considering the measurement of preferences for life quality. The aim is also to examine whether the results obtained are consistent with the theoretical assumptions that are required for the preference to be accepted as a cardinal utility. A quantitative survey was carried out with 58 medical and 61 economics students. Half of the students received PTO and the other half TTO questions. The data collected was analyzed comparing the methods, the two student groups and men against women.</p><p>The results from the survey show that, both with TTO and PTO, respondents on average believe that patients who are at a lower initial health level should be given priority over patients who are at a higher initial health level, and younger patients should be given priority over older patients. No significant differences were seen between PTO and TTO when it came to the age of the patient. Conversely, there was a significant difference between the methods for the valuation based on initial health status of patients. Measured with PTO a treatment for patients who are at a lower initial level is valued 28% higher than a treatment for those patients who are at a higher initial level, while the corresponding figure for TTO was 8%. Between medical students and economic students, there were significant differences in the question of age in the PTO. Between men and women differences were found in both methods.</p> / <p>Kostnadseffektivitet är en av faktorerna som ska tas i beaktande vid beslut om hur resurser inom hälso- och sjukvården ska fördelas. Kvalitetsjusterade levnadsår (QALY) används för att mäta effekten av olika insatser. Måttet baseras på nyttomaximeringsteori vilket leder till att en QALY alltid är en QALY oavsett vem den tillfaller - med andra ord är en QALY som produceras hos en patient lika mycket värd oavsett exempelvis patientens ålder eller initiala tillstånd. Dessa antaganden har i tidigare undersökningar visat sig stämma dåligt med individers preferenser men olika metoder för att ta fram QALY verkar ta olika mycket hänsyn till dem. Två av flera metoder är Time Trade Off (TTO), där respondenter ställs inför en värdering av hälsoförändringar i tid och Person Trade Off (PTO) där respondenter ställs inför en värdering i personer. PTO har påståtts vara en mer rättvisande metod som tar större hänsyn till hur individer vill att samhälleliga resurser ska fördelas. Denna uppsats syftar till att, utifrån ett fördelningsperspektiv med fokus på ålder och initialt hälsotillstånd, empiriskt kartlägga förekomsten av skillnader i preferenser för livskvalitet mätt med PTO respektive TTO, samt att undersöka om de erhållna resultaten överensstämmer med de teoretiska grundantagandena som krävs för att preferenser ska accepteras som kardinala nyttor. För att svara mot syftet utfördes en kvantitativ undersökning på 58 läkar- samt 61 ekonomistudenter. Hälften av studenterna fick PTO-frågor och den andra hälften TTO-frågor. En statistisk bearbetning av insamlad data har gjorts där svaren har jämförts mellan metoderna samt mellan läkar- och ekonomistudenter och kvinnor och män.</p><p>Resultaten från undersökningen visar att både med TTO och PTO anser respondenterna att patienter som befinner sig på en lägre initial nivå ska prioriteras framför patienter som befinner sig på en högre initial nivå samt yngre patienter ska prioriteras framför äldre patienter. Vad gäller hänsyn till patienters ålder uppmättes inga signifikanta skillnader mellan PTO och TTO. Däremot uppmättes en signifikant skillnad mellan metoderna vad gäller hänsyn till initialt hälsotillstånd hos patienter. Mätt med PTO värderas en behandling för de patienter som befinner sig på en lägre initial nivå 28 % högre än en behandling för de patienter som befinner sig på en högre initial nivå medan motsvarande siffra för TTO var 8%. Mellan läkare och ekonomer fanns signifikanta skillnader i frågan gällande ålder i PTO och mellan kvinnor och män återfanns skillnader i båda metoder.</p>

One must consider cost effectiveness when deciding how resources within the health sector should be distributed. Quality adjusted life years (QALYs) are used to measure the value of different medical treatments. QALY is based on utility maximization theory, which suggests that a QALY is always a QALY regardless of who receives it. Therefore, a produced QALY is worth the same regardless of the age or the initial health of the patient. Previous research has shown that these assumptions do not seem to fit the real preferences of individuals. Further, there are different methods of acquiring QALYs that give different outcomes. Two of these methods are Time Trade Off (TTO), in which respondents are confronted with a valuation of health change in time, and Person Trade Off (PTO), where respondents are confronted with a valuation in persons. Arguably, PTO is the preferred method that takes greater account of how individuals wish to allocate the resources of the society. From a distribution perspective focusing on age and initial health status, this paper aims to empirically identify the differences between TTO and PTO considering the measurement of preferences for life quality. The aim is also to examine whether the results obtained are consistent with the theoretical assumptions that are required for the preference to be accepted as a cardinal utility. A quantitative survey was carried out with 58 medical and 61 economics students. Half of the students received PTO and the other half TTO questions. The data collected was analyzed comparing the methods, the two student groups and men against women. The results from the survey show that, both with TTO and PTO, respondents on average believe that patients who are at a lower initial health level should be given priority over patients who are at a higher initial health level, and younger patients should be given priority over older patients. No significant differences were seen between PTO and TTO when it came to the age of the patient. Conversely, there was a significant difference between the methods for the valuation based on initial health status of patients. Measured with PTO a treatment for patients who are at a lower initial level is valued 28% higher than a treatment for those patients who are at a higher initial level, while the corresponding figure for TTO was 8%. Between medical students and economic students, there were significant differences in the question of age in the PTO. Between men and women differences were found in both methods. / Kostnadseffektivitet är en av faktorerna som ska tas i beaktande vid beslut om hur resurser inom hälso- och sjukvården ska fördelas. Kvalitetsjusterade levnadsår (QALY) används för att mäta effekten av olika insatser. Måttet baseras på nyttomaximeringsteori vilket leder till att en QALY alltid är en QALY oavsett vem den tillfaller - med andra ord är en QALY som produceras hos en patient lika mycket värd oavsett exempelvis patientens ålder eller initiala tillstånd. Dessa antaganden har i tidigare undersökningar visat sig stämma dåligt med individers preferenser men olika metoder för att ta fram QALY verkar ta olika mycket hänsyn till dem. Två av flera metoder är Time Trade Off (TTO), där respondenter ställs inför en värdering av hälsoförändringar i tid och Person Trade Off (PTO) där respondenter ställs inför en värdering i personer. PTO har påståtts vara en mer rättvisande metod som tar större hänsyn till hur individer vill att samhälleliga resurser ska fördelas. Denna uppsats syftar till att, utifrån ett fördelningsperspektiv med fokus på ålder och initialt hälsotillstånd, empiriskt kartlägga förekomsten av skillnader i preferenser för livskvalitet mätt med PTO respektive TTO, samt att undersöka om de erhållna resultaten överensstämmer med de teoretiska grundantagandena som krävs för att preferenser ska accepteras som kardinala nyttor. För att svara mot syftet utfördes en kvantitativ undersökning på 58 läkar- samt 61 ekonomistudenter. Hälften av studenterna fick PTO-frågor och den andra hälften TTO-frågor. En statistisk bearbetning av insamlad data har gjorts där svaren har jämförts mellan metoderna samt mellan läkar- och ekonomistudenter och kvinnor och män. Resultaten från undersökningen visar att både med TTO och PTO anser respondenterna att patienter som befinner sig på en lägre initial nivå ska prioriteras framför patienter som befinner sig på en högre initial nivå samt yngre patienter ska prioriteras framför äldre patienter. Vad gäller hänsyn till patienters ålder uppmättes inga signifikanta skillnader mellan PTO och TTO. Däremot uppmättes en signifikant skillnad mellan metoderna vad gäller hänsyn till initialt hälsotillstånd hos patienter. Mätt med PTO värderas en behandling för de patienter som befinner sig på en lägre initial nivå 28 % högre än en behandling för de patienter som befinner sig på en högre initial nivå medan motsvarande siffra för TTO var 8%. Mellan läkare och ekonomer fanns signifikanta skillnader i frågan gällande ålder i PTO och mellan kvinnor och män återfanns skillnader i båda metoder.