Vazamentos em tubos pressurizados geram ondas acústicas que se propagam através das paredes destes tubos, as quais podem ser captadas por acelerômetros ou por sensores de emissão acústica. O conhecimento de como estas paredes podem vibrar, ou de outro modo como as ondas acústicas se propagam neste meio, é fundamental em um processo de detecção e localização da fonte de vazamento. Neste trabalho, foi implementado um modelo analítico, através das equações de movimento da casca cilíndrica, com o objetivo de entender o comportamento da superfície do tubo em função de uma excitação pontual. Como a superfície cilíndrica é um meio fechado na direção circunferencial, ondas que iniciaram sua jornada, a partir de uma fonte pontual sobre a superfície, se encontrarão com outras que já completaram a volta na casca cilíndrica, tanto no sentido horário como no anti-horário, gerando interferências construtivas e destrutivas. Após um tempo suficiente, uma estacionariedade é atingida, criando pontos de picos e vales na superfície da casca, os quais podem ser visualizadas através de uma representação gráfica do modelo analítico criado. Os resultados teóricos foram comprovados através de medidas realizadas em uma bancada de testes composta de um tubo de aço terminado em caixa de areia, simulando a condição de tubo infinito. Para proceder à localização da fonte pontual sobre a superfície, adotou-se o processo de solução inversa, ou seja, conhecidos os sinais dos sensores dispostos na superfície do tubo, determina-se através do modelo teórico onde a fonte que gerou estes sinais pode estar. / Leaks in pressurized tubes generate acoustic waves that propagate through the walls of these tubes, which can be captured by accelerometers or by acoustic emission sensors. The knowledge of how these walls can vibrate, or in another way, how these acoustic waves propagate in this material is fundamental in the detection and localization process of the leak source. In this work an analytic model was implemented, through the motion equations of a cylindrical shell, with the objective to understand the behavior of the tube surface excited by a point source. Since the cylindrical surface has a closed pattern in the circumferential direction, waves that are beginning their trajectory will meet with another that has already completed the turn over the cylindrical shell, in the clockwise direction as well as in the counter clockwise direction, generating constructive and destructive interferences. After enough time of propagation, peaks and valleys in the shell surface are formed, which can be visualized through a graphic representation of the analytic solution created. The theoretical results were proven through measures accomplished in an experimental setup composed of a steel tube finished in sand box, simulating the condition of infinite tube. To determine the location of the point source on the surface, the process of inverse solution was adopted, that is to say, known the signals of the sensor disposed in the tube surface, it is determined through the theoretical model where the source that generated these signals can be.

Vazamentos em tubos pressurizados geram ondas acústicas que se propagam através das paredes destes tubos, as quais podem ser captadas por acelerômetros ou por sensores de emissão acústica. O conhecimento de como estas paredes podem vibrar, ou de outro modo como as ondas acústicas se propagam neste meio, é fundamental em um processo de detecção e localização da fonte de vazamento. Neste trabalho, foi implementado um modelo analítico, através das equações de movimento da casca cilíndrica, com o objetivo de entender o comportamento da superfície do tubo em função de uma excitação pontual. Como a superfície cilíndrica é um meio fechado na direção circunferencial, ondas que iniciaram sua jornada, a partir de uma fonte pontual sobre a superfície, se encontrarão com outras que já completaram a volta na casca cilíndrica, tanto no sentido horário como no anti-horário, gerando interferências construtivas e destrutivas. Após um tempo suficiente, uma estacionariedade é atingida, criando pontos de picos e vales na superfície da casca, os quais podem ser visualizadas através de uma representação gráfica do modelo analítico criado. Os resultados teóricos foram comprovados através de medidas realizadas em uma bancada de testes composta de um tubo de aço terminado em caixa de areia, simulando a condição de tubo infinito. Para proceder à localização da fonte pontual sobre a superfície, adotou-se o processo de solução inversa, ou seja, conhecidos os sinais dos sensores dispostos na superfície do tubo, determina-se através do modelo teórico onde a fonte que gerou estes sinais pode estar. / Leaks in pressurized tubes generate acoustic waves that propagate through the walls of these tubes, which can be captured by accelerometers or by acoustic emission sensors. The knowledge of how these walls can vibrate, or in another way, how these acoustic waves propagate in this material is fundamental in the detection and localization process of the leak source. In this work an analytic model was implemented, through the motion equations of a cylindrical shell, with the objective to understand the behavior of the tube surface excited by a point source. Since the cylindrical surface has a closed pattern in the circumferential direction, waves that are beginning their trajectory will meet with another that has already completed the turn over the cylindrical shell, in the clockwise direction as well as in the counter clockwise direction, generating constructive and destructive interferences. After enough time of propagation, peaks and valleys in the shell surface are formed, which can be visualized through a graphic representation of the analytic solution created. The theoretical results were proven through measures accomplished in an experimental setup composed of a steel tube finished in sand box, simulating the condition of infinite tube. To determine the location of the point source on the surface, the process of inverse solution was adopted, that is to say, known the signals of the sensor disposed in the tube surface, it is determined through the theoretical model where the source that generated these signals can be.

<p>Animal behavior observation is a widely used method of detecting when animals are ill or injured, but there are limitations to using behavioral observations. Behavioral observations can be labor-intensive, subjective and unreliable. The development of technologies such as accelerometers, which record acceleration and activity-based data in 3D space, enables faster, more accurate and quantitative methods of detecting changes in animal behavior. Previous research has demonstrated the utility of using accelerometers to detect changes in animals’ health and well-being. However, limited information is available on the use of accelerometers to detect changes in behavior due to heat stress, which is a major poultry welfare concern, or to detect changes in activity levels of turkeys. The overall objective of this study was to determine whether micro-acceleration data loggers (accelerometers) can be used to detect changes in turkeys’ activity levels and to identify changes in turkey behavior that are indicative of changes in turkey well-being. Two trials were conducted. Specific objectives for Trial 1 were to: 1) determine the effects of accelerometers and habituation to accelerometers on turkey gait and welfare, 2) determine age-related changes in gait and welfare, and 3) evaluate the validity of the accelerometers. Thirty-six male commercial turkeys were randomly assigned to one of five groups: accelerometer and habituation period (AH), accelerometer and no habituation (AN), VetRap bandage (no accelerometer) and habituation (VH), bandage (no accelerometer) and no habituation (VN), and nothing on either leg (C). Welfare was assessed prior to video-recording birds as they walked across a Tekscan® pressure pad at 8, 12 and 16 wk to determine effects of treatment on number of steps, cadence, gait time, gait distance, gait velocity, impulse, gait cycle time, maximum force, peak vertical pressure, single support time, contact time, step length, step time, step velocity, stride length, total double support time, and duty factor. Accelerometer validity and reliability were determined by comparing the number of steps detected with the accelerometer to the number of steps determined from video recordings. Several age-related changes in turkey gait were found regardless of habituation, including a slower cadence at 16 wk, shorter gait distance at 8 wk, and slower gait velocity at 16wk. Habituation to the accelerometer and bandage had limited effects on turkey gait: non-habituated turkeys (VN and AN) spent more time standing on two feet (total double support time) compared to C birds, but did not differ from habituated (VH and AH) birds. Accelerometer validity and reliability were affected by both age and treatment. Validity and reliability were lowest for non-habituated birds (AN). Precision and sensitivity of accelerometers decreased with age but were unaffected by treatment. False discovery rate increased, and accuracy and specificity decreased with age. Results demonstrated that micro-data loggers do not adversely affect turkey welfare, but habituation to wearing accelerometers affects accelerometer reliability and validity. Accelerometer validity and turkey gait are also greatly affected by the age of the turkeys. </p> <p> </p> <p>The second experiment used the validated accelerometers to assess changes in walking activity when turkeys were under an immune challenge or mild heat stress. Another objective of Experiment 2 was to identify changes in welfare and behavior associated with mild heat stress and a mild immune challenge. A total of 92 tom turkeys (trial 1: 51 turkeys; trial 2: 41 turkeys) were assigned to 3 different treatments in a crossover design: control (C; no heat stress or immune challenge), heat stress (HS), and immune challenge (IC). HS treatment was induced by slowly heating rooms to a peak temperature before slowly returning the rooms to normal temperatures. IC treatment was induced by a live-virus hemorrhagic enteritis vaccine which was added to the drinking water. Video (walking, sitting, standing, eating, drinking, preening, feather pecking, aggression and heat-stress related behavior) and accelerometer (steps/hr) data were recorded for 5 days at 10, 12, and 14 wk of age in order to gather behavior and walking activity data pre and post treatment, which occurred on day 3 of the 5 day period. Steps/hr decreased with age, treatments HS and IC had lower step counts compared to control groups, and each day proved to have a different step count regardless of whether a treatment was imposed. On the day of the imposed treatments, steps/hr were lower for both HS and IC turkeys. Welfare analysis indicated that tail and wing feather condition was worse at 14 wk compared to 10 and 12 wk. Behaviorally, the amount of time spent sitting increased as birds aged. Treatment also affected behavior: HS and IC turkeys performed less standing and walking compared to C birds on the day of the imposed treatment. Turkeys under a heat stress treatment performed more aggressive interactions and were observed performing heat-stress related behavior, including panting and sitting with their wings spread apart. </p> <p> </p> <p>Results from both trials indicated that accelerometers can be useful tools to assess walking activity of turkeys and that accelerometers have the potential to detect changes in behavior that may be associated with conditions that negatively impact turkey welfare. The process of wearing an accelerometer on the leg did not adversely affect turkey welfare, but habituation is important to ensure that accelerometers are accurately and reliably recording turkeys’ steps. In addition, it was determined that changes in behavior, such as decreased walking and standing, can be indicative of potential welfare issues, such as heat stress and an immune challenge in turkeys. Further research is needed to explore the best step threshold for particular turkey ages in order to get the most accurate data in future analysis of walking activity. Furthermore, sex differences were not a factor in these studies as only male turkeys were used which may differ from females in terms of gait and behavior under heat stress and an immune challenge. It may also be beneficial to further explore turkey gait as there were discrepancies in the literature and this study concerning age related differences in gait (duty factor). Future research should focus on the early detection potential accelerometers can provide to the turkey industry for welfare concerns. As shown by our results, walking activity decreases under both a mild heat stress and immune challenge, so future studies should now determine if this decrease in activity level is detectable before overt visual behavioral signs. If accelerometers can detect signs of stress more objectively, accurately, and quicker than visual inspection, then both farmers and researchers could benefit from utilizing these devices to improve animal welfare in the future.</p>

<p>The purpose of this report is to evaluate different methods for identifying states in robot models. Both linear and non-linear filters exist among these methods and are compared to each other. Advantages, disadvantages and problems that can occur during tuning and running are presented. Additional measurements from accelerometers are added and their use with above mentioned methods for state estimation is evaluated. The evaluation of methods in this report is mainly based on simulations in Matlab, even though some experiments have been performed on laboratory equipment. </p><p>The conclusion indicates that simple non-linear models with few states can be more accurately estimated with a Kalman filter than with an extended Kalman filter, as long as only linear measurements are used. When non-linear measurements are used an extended Kalman filteris more accurate than a Kalman filter. Non-linear measurements are introduced through accelerometers with non-linear measurement equations. Using accelerometers generally leads to better state estimation when the measure equations have a simple relation to the model.</p>

The purpose of this report is to evaluate different methods for identifying states in robot models. Both linear and non-linear filters exist among these methods and are compared to each other. Advantages, disadvantages and problems that can occur during tuning and running are presented. Additional measurements from accelerometers are added and their use with above mentioned methods for state estimation is evaluated. The evaluation of methods in this report is mainly based on simulations in Matlab, even though some experiments have been performed on laboratory equipment. The conclusion indicates that simple non-linear models with few states can be more accurately estimated with a Kalman filter than with an extended Kalman filter, as long as only linear measurements are used. When non-linear measurements are used an extended Kalman filteris more accurate than a Kalman filter. Non-linear measurements are introduced through accelerometers with non-linear measurement equations. Using accelerometers generally leads to better state estimation when the measure equations have a simple relation to the model.

This thesis presents the development of high resolution, wide dynamic range sigma-delta type readout circuits for capacitive MEMS accelerometers. Designed readout circuit employs fully differential closed loop structure with digital output, achieving high oversampling ratio and high resolution. The simulations of the readout circuit together with the accelerometer sensor are performed using the models constructed in Cadence and Matlab Simulink environments. The simulations verified the stability and proper operation of the accelerometer system. The sigma-delta readout circuit is implemented using XFab 0.6 &micro / m CMOS process. Readout circuit is combined with Silicon-On-Glass (SOG) and Dissolved Wafer Process (DWP) accelerometers. Both open loop and closed loop tests of the accelerometer system are performed. Open loop test results showed high sensitivity up to 8.1 V/g and low noise level of 4.8 &micro / g/&amp / #61654 / Hz. Closed loop circuit is implemented on a PCB together with the external filtering and decimation electronics, providing 16-bit digital output at 800 Hz sampling rate. High acceleration tests showed &plusmn / 18.5 g of linear acceleration range with high linearity, using DWP accelerometers. The noise tests in closed loop mode are performed using Allan variance technique, by acquiring the digital data. Allan variance tests provided 86 &micro / g/&amp / #61654 / Hz of noise level and 74 &micro / g of bias drift. Temperature sensitivity tests of the readout circuit in closed loop mode is also performed, which resulted in 44 mg/&ordm / C of temperature dependency. Two different types of new adaptive sigma-delta readout circuits are designed in order to improve the resolution of the systems by higher frequency operation. The two circuits both change the acceleration range of operation of the system, according to the level of acceleration. One of the adaptive circuits uses variation of feedback time, while the other circuit uses multi-bit feedback method. The simulation results showed micro-g level noise in closed loop mode without the addition of the mechanical noise of the sensor.

L’obésité et la sédentarité sont considérées comme des problèmes importants de santé publique. L’augmentation de l’activité physique est une des stratégies recommandées pour obtenir un bilan énergétique positif dans les interventions de perte de poids. Deux accéléromètres, le Sensewear Armband (SWA) et l’Actical (ACT), sont des outils simples à utiliser en recherche clinique, mais à notre connaissance, aucune étude n’a évalué leur capacité à détecter des hausses de la dépense énergétique. De plus, très peu d’études, avec des résultats par ailleurs contradictoires, ont été effectuées afin de déterminer la fiabilité de ces accéléromètres pour la mesure de la dépense énergétique au repos et au cours d’une activité physique au vélo stationnaire. Ainsi, les objectifs de cette étude étaient: 1) évaluer, pendant 3 journées consécutives, la reproductibilité des valeurs de la dépense énergétique obtenues avec le SWA et l’ACT, au repos et au cours d’une activité physique de 45 minutes sur un vélo stationnaire, 2) déterminer la capacité de ces accéléromètres à détecter des hausses de 5% et 10 % de la dépense énergétique totale (DET) au moyen de la modification d’une activité physique au tapis roulant pendant 45 minutes. Cette étude transversale effectuée auprès de 20 sujets en santé, âgés de 20 à 32 ans et avec un IMC moyen de 23 kg/m2, consistait en 5 visites à la clinique. Les 3 dernières visites, sous supervision directe pendant 10 heures, comportaient des activités programmées sur le vélo stationnaire et la marche sur tapis roulant pendant 45 minutes. Les résultats montrent que le SWA et l’ACT donnent des valeurs reproductibles pour estimer la dépense énergétique au repos et la dépense énergétique au vélo (corrélations intra classe, p<0,001). Par contre, pour des hausses préétablies de la DET de 5% et 10%, les estimations respectives obtenues étaient de 1,4% et 7,8% avec le SWA et de 3,4% et 13,1% avec l’ACT. Le SWA sous-estime les hausses de 5% et de 10% et l’ACT sous-estime la hausse de 5% et surestime la hausse de 10% de la DET. Plus de recherches sont nécessaires avant de confirmer l’usage du SWA et de l’ACT dans l’estimation des hausses de la dépense énergétique totale. / Obesity and physical inactivity are considered significant public health problems. Increasing physical activity is one strategy recommended to induce a positive energy balance in weight loss interventions. Two accelerometers, the Sensewear Armband (SWA) and Actical (ACT), are simple tools to use in research, but to our knowledge, no studies have assessed their capacity to detect increases in energy expenditure. Moreover, very few studies, and with conflicting results, have been conducted to determine the reliability of these accelerometers for the measurement of resting energy expenditure and physical activity energy expenditure on a stationary bicycle. Thus the objectives of this study were as follows : 1) evaluate, during 3 consecutive days, the reproducibility of values of energy expenditure obtained with the SWA and the ACT, at rest and during physical activity for 45 minutes on a stationary bicycle, 2) determine the capacity of these accelerometers to detect increases of 5% and 10% in total energy expenditure (TEE) obtained by modifying an activity on a treadmill for 45 minutes. This cross-sectional study conducted with 20 healthy subjects, aged 20-32 years with an average BMI of 23 kg/m2, consisted of 5 visits to the clinic. The last 3 visits, under direct supervision for 10 hours, included programmed physical activities on a stationary bicycle and on a treadmill for 45 minutes. The results show that the SWA and the ACT provide values which are reproducible for estimating resting energy expenditure and physical activity energy expenditure on the stationary bicycle (intra-class correlations, p<0,001). However, for pre-established increases in TEE of 5% and 10%, corresponding estimations obtained were 1.4% and 7.8% with the SWA and 3.4% and 13.1% with the ACT. The SWA underestimates increases of 5% and 10% and the ACT underestimates increases of 5% and overestimates increases of 10% of TEE. More research is needed before confirming the use of the SWA and the ACT in the estimation of increases in total energy expenditure.

During monitoring of rear-mounted equipment, frequent rearward turning of tractor drivers in awkward postures can cause musculoskeletal disorders related to the back, neck, and shoulders. A camera-based monitoring system, consisting of one or more cameras placed on the implement and a monitor placed inside the tractor cab, has potential ergonomic benefits compared with traditional implement monitoring strategies by reducing the rearward turning and twisting movements of tractor drivers. A camera-based monitoring system was compared with two traditional monitoring strategies (direct looking and using rear-view mirrors) in a lab environment using a Tractor Air-Seeder Driving Simulator. The operator’s reaction time and response errors, head/neck movement (acceleration), and neck muscle temperature were compared for the three monitoring strategies. The camera-based monitoring system yielded significantly (α=0.05) better outcomes in terms of acceleration and muscle temperature values. No significant difference was observed for response errors.

During monitoring of rear-mounted equipment, frequent rearward turning of tractor drivers in awkward postures can cause musculoskeletal disorders related to the back, neck, and shoulders. A camera-based monitoring system, consisting of one or more cameras placed on the implement and a monitor placed inside the tractor cab, has potential ergonomic benefits compared with traditional implement monitoring strategies by reducing the rearward turning and twisting movements of tractor drivers. A camera-based monitoring system was compared with two traditional monitoring strategies (direct looking and using rear-view mirrors) in a lab environment using a Tractor Air-Seeder Driving Simulator. The operator’s reaction time and response errors, head/neck movement (acceleration), and neck muscle temperature were compared for the three monitoring strategies. The camera-based monitoring system yielded significantly (α=0.05) better outcomes in terms of acceleration and muscle temperature values. No significant difference was observed for response errors.

La compréhension des déterminants de l’activité physique (AP) et de l’activité sédentaire (AS) constitue un problème de santé public majeur en vue de promouvoir l’AP et de diminuer l’AS. Les principaux objectifs de cette recherche sont a) décrire les niveaux d'activité physique modérée à vigoureuse (APMV) et les niveaux d’AS d’adolescents des villes de Tarbes (France) et Huesca (Espagne) et b) analyser l'influence de plusieurs facteurs environnementaux, sociaux et psychologiques sur les niveaux de ces mêmes variables. Les cadres théoriques des modèles socio-écologiques et de la théorie de l’autodétermination ont été utilisées comme base à ce travail. Un total de 828 adolescents (14.32±.73 ans), dont 50,5% d'espagnols, a participé au projet. Cette thèse se compose de six études. Les résultats ont montré que les niveaux d’APMV sont plus élevés en Espagne (~ 60 minutes/jour) qu'en France (~ 47 minutes/jour). Ces différences ont été mises en évidence lors de presque tous les moments de la semaine, à l’exception du temps scolaire. Il a été également montré que la pratique de plusieurs comportements sédentaires (SB) semble excessive, aussi bien en Espagne qu’en France (plus de deux heures par jour de temps d'écran). L’analyse des déterminants montre que des températures plus élevées, des niveaux de précipitation plus faibles et l'utilisation du transport actif favorisent des niveaux plus élevés d’APMV dans les deux pays. Il apparaît également qu’une motivation plus autodéterminée, des niveaux plus élevés de satisfaction des besoins psychologiques fondamentaux (compétence et affiliation) ainsi qu’un soutien plus élevé du père conduisent à des niveaux plus élevés d’APMV. / Physical activity (PA) and its factors of influence constitute important elements of study. The main objectives of this research are a) to describe the moderate-to-vigorous physical activity (MVPA) levels and sedentary activity levels of a sample of adolescents from cities of Tarbes (France) and Huesca (Spain), and b) to analyse the influence of several environmental, social, and psychological factors on their PA levels. A total of 828 adolescents (14.32±.73 years), of which 50.5% were Spaniards, took part in the project. This dissertation is made up of six studies. Results showed that MVPA levels are higher in Spain (~ 60 minutes) than in France (~ 47 minutes). These differences were found at almost any given time of the week, except during school time. Results also showed that the practice of several sedentary behaviours (SB) seems excessive, both in Spain and France (more than two hours per day of screen time). Considering factors of influence, it can be said that warmer temperatures, lower levels of rainfall and the use of active transport all promote higher MVPA levels in both countries. It is also shown how more self-determined motivation, higher levels of basic psychological needs satisfaction (except the perception of autonomy) and greater support from the father lead to higher MVPA levels. Programmes to promote PA need to be implemented.