La quête de l’augmentation de l’espérance de vie chez l’homme inspire depuis longtemps les travaux de recherche, en particulier en biologie. Au-delà de la notion de mortalité, celles de la morbidité et de l’espérance de vie active et indépendante sont aujourd’hui au centre des enjeux de santé publique. En effet, la perte d’autonomie chez les personnes âgées nous oriente vers un objectif d’amélioration de l’espérance de vie en bonne santé. L’activité physique est un facteur fondamental du bien-être de l’individu, impactant aussi bien les performances physiques que les diverses pathologies (diabètes, pathologies cardiaques). Chez la population âgée, la nécessité d’obtenir des résultats rapides, sans souffrance ni longs entraînements nous a mené à notre première étude. Celle-ci a porté sur l’application d’un nouveau protocole d’entraînement à court terme utilisant l’accélération chez les souris âgées. Les résultats obtenus nous ont montré une amélioration des performances physiques et de l’ensemble des métabolismes énergétiques, tout en étant plus efficient qu’un entraînement en endurance et plus adapté qu’un entraînement en intervalles. De plus, devant l’intérêt récent que suscitent les transferts énergétiques dans la régulation des métabolismes énergétiques et dans le processus du vieillissement, nous nous sommes intéressés à la compréhension des mécanismes des flux énergétiques, et notamment à celui faisant intervenir la créatine kinase mitochondriale. Notre seconde étude a ainsi analysé les capacités physiques et physiologiques de souris déficientes à la créatine kinase mitochondriale de 6 à 18 mois. Nos résultats suggèrent une utilisation majoritaire du métabolisme lipidique et un maintien des capacités physiques chez ces souris déficientes à la créatine kinase mitochondriale. La compréhension des mécanismes du flux énergétique et de leur importance sur les capacités physiques au cours du vieillissement permettrait de mieux concevoir les futurs protocoles d’entraînement, tel que l’entraînement en accélération nous ouvrant de nouvelles perspectives dans l’amélioration des capacités physiques et de l’autonomie au cours du vieillissement. / For a long time, the increase in life expectancy in humans inspires research, especially in biology. Beyond the notion of mortality, those of morbidity and active and independent life expectancy are at the center of public health issues. However, faced with the decrease in physical capacity and the increase in the number of diseases during aging, interest is now focused on improving the quality of life. Indeed, the loss of autonomy in the elderly directs us towards a goal of improving the healthspan. Physical activity is a fundamental factor in the well-being, impacting physical performance as well as different pathologies (diabetes, cardiac pathologies). In the elderly population, the necessity to reach fast results, without suffering or long time training led to our first study. This one focused on a new model of short acceleration-based training protocol in elderly mice. The results showed an improvement in physical performance and in the whole of the energetic metabolisms, while being more efficient than endurance training and more suitable than interval training. Moreover, given the recent interest in energy transfers in the regulation of energetic metabolisms and in the aging process, we were interested in understanding the mechanisms of energy flux and in particular the one involving mitochondrial creatine kinase. Our second study analyzed the physical and physiological capacity of mitochondrial creatine kinase deficient mice from 6 to 18 months. Our results suggest a predominant lipid metabolism and showed a conservation of physical abilities in these mitochondrial creatine kinase deficient mice. Knowledge of the mechanisms of energy flux and their importance to physical capacities during aging would lead to better design future training protocols, such as our acceleration training, which opens new perspectives in improvement of physical capacity and autonomy during aging.

The purpose of this work is to implement four additional inviscid flux methods in the U2NCLE solver being developed at Mississippi State University. The goal is that some or all of these methods may provide benefits over the current options with respect to accuracy or robustness. These four methods include both the Harten, Lax, Van Leer, Einfeldt (HLLE) and Harten, Lax, Van Leer ? Contact (HLLC) methods as well as the Advection Upstream Splitting Method (AUSM) and its successor AUSM+. The HLL family, which includes both HLLE and HLLC are based on the Riemann problem, which is divided into a number of states. The AUSM family attempts to combine the effects of both flux vector and flux difference splittings to create better schemes. Several simple and complex cases were run with each new method and compared to the methods currently available as well as experimental and analytical results when available. The results of the simple tests showed that all the methods were similarly suited for delivering accurate results on simple cases. In more complex cases, however, the AUSM family proved to be less robust and failed to converge for the final case. The HLLE method showed excellent robustness qualities but seemed to over predict the viscous values in several cases. The HLLC method proved equally as accurate and robust as Roe's Method.

The flux-weakening control (FWC) methods for interior permanent magnet synchronous motors (IPMSMs) with torque performance improvement are studied in this thesis. A FWC strategy with constant parameters is proposed, which achieves the extended dc-link voltage utilization and improves the tracking performance. The voltage trajectory is extended to the overmodulation region to increase the dc-link voltage utilization rate and torque. Moreover, a current predictive controller is implemented to improve tracking performance. A FWC method considering the resistive voltage drop and magnetic saturation is proposed. The proposed method achieves the voltage extension, torque improvement, and improved dynamic performance by establishing a new stator flux linkage adjustment method. The stator flux linkage reference is adjusted based on the torque reference, operating speed, and modulation index. Two voltage feedback paths are established and chosen based on the torque reference and operating speed. The stator resistance and nonlinear inductance characteristics are constructed based on the experimental test. Thus, accurate current control is achieved. Compared to feedforward-based FWC methods, the proposed method improves the output torque and power. Compared to feedback-based FWC methods, the proposed method improves the dynamic performance and avoids the voltage saturation and windup problem. Compared to the mixed FWC methods, which only have one feedback path, the proposed method improves the dynamic performance. The influence of extended dc-link voltage utilization is analyzed. The nonlinear relationship between voltage and torque is solved mathematically. The torque, torque ripple, and current ripple trends with modulation index in voltage extension region are analyzed, and the harmonic spectra of voltage, current, and torque with or without voltage extension are compared, which provide the guidance to make the tradeoff between maximizing the torque and torque ripple alleviation. / Thesis / Master of Applied Science (MASc)

The effects of shock wave impact on unsteady turbine heat transfer are investigated. A numerical approach is developed to simulate the flow physics present in a previously performed unsteady wind tunnel experiment. The windtunnel experiment included unheated and heated flows over a cascade of highly loaded turbine blades. After the flow over the blades was established, a single shock with a pressure ratio of 1.1 was introduced into the wind tunnel test section. A single blade was equipped with pressure transducers and heat flux microsensors. As the shock wave strikes the blade, time resolved pressure, temperature, and heat transfer data were recorded. / Ph. D.

Modeling the Cosmic Muon Flux is very important for quantifying the backgrounds present for underground experiments. We measure the flux at various locations in the Kimballton Underground Research Facility (KURF) and compare these measurements with our model. / Ph. D.

No description available.

De Bruin och Hartogensis har föreslagit en ny metod för att beräkna impulsflödet och det sensibla värmeflödet vid stabila förhållanden. Metoden bygger på att de normaliserade standardavvikelserna är approximativt konstanta för den horisontella vinden och temperaturen. Beräkningarna görs endast utifrån medelvinden och temperaturen och dess standardavvikelser. Den här metoden testas i den här studien med datamaterial från Labans kvarnar på Gotland i Östersjön och Östergarnsholm som ligger 4 km utanför Gotland. Labans kvarnar representerar flöden över land och Östergarnsholm flöden över hav. Konstanterna som De Bruin och Hartogensis använde är följande: Cu=2.5 och CT=2.3, vilket gav en mycket liten spridning i deras beräkningar av flöden. Datamaterialet de använde sig av var från Kansas, USA, över en plan grässlätt. Olika statistiska mått har här testats för att erhålla värden på konstanterna. Medel-, median- och typvärde för de normaliserade standardavvikelserna för respektive kvantitet har beräknats. För landförhållanden i den här studien fås lite högre värden på konstanterna, Cu=2.6 och CT=2.6, än vad De Bruin och Hartogensis erhöll.  Vid beräkningar av flöden över hav delas vindriktningen upp i två intervall. Vindriktningen som ligger mellan 220o - 300o representerar vindar som blåser ifrån Gotland och vindriktningar som ligger mellan 80o - 220o representerar vindar från öppet hav. För öppna havsförhållanden fås konstanter som har ett lägre värde vid beräkning av impulsflödet, Cu=2.2 , än de värde som De Bruin och Hartogensis fick. För vindar som blåser ifrån Gotland erhålls konstanten till:Cu=3.0. Konstanter för beräkning av värmeflödet är svårare att bestämma och ger inte alls lika bra resultat över hav som för impulsflödet. Bestämningar av värmeflöde är mycket mer komplicerade än för impulsflöde. Delvis på grund av att det behövs två konstanter, men det beror också på att temperaturstrukturen i det marina gränsskiktet inte följer Monin-Obukhovs similaritetsteori.Framsidans foto / De Bruin and Hartogensis have proposed a new method to determine momentum flux and sensible heat flux at stable conditions. When using this method the assumption is made that the standard deviations for the longitudinal wind component and temperature are approximately constant. Only the mean wind and the temperature and the standard deviations are necessary for the calculations. The method has been analyzed in this study with data from Labans kvarnar sited on Gotland in the Baltic Sea and Östergarnsholm which is situated 4 km outside Gotland. Labans kvarnar represents fluxes over land and Östergarnsholm represents fluxes over sea. The constants that De Bruin and Hartogensis found are the following:Cu=2.5 for wind speed and CT=2.3  for temperature, which shows very little scatter in the calculations of the fluxes. The data they used where measured in Kansas over a very flat grassland site. Different statistics measurements have been tested to receive values of the constants. In search of constants the mean value, median value and the modal value for respectively quantity have been calculated. For land conditions the values of the constants are a little bit higher, Cu=2.6 and CT=2.6, than the values De Bruin and Hartogensis received. When calculating the fluxes over ocean the wind direction is divided in to two intervals. The wind direction between 220o - 300o represents winds from Gotland and wind direction between  80o - 220o represents winds from open sea. For the open sea conditions the constants calculated for the momentum flux in this study are a little bit lower, Cu=2.2, than the value De Bruin and Hartogensis found. For winds from Gotland the constant for momentum flux was found to be: Cu=3.0. When calculating the sensible heat flux the constants are very difficult to find and do not give as good result as for the momentum flux over sea. The conditions for the sensible heat are much more complicated than it is for momentum flux. Firstly two constants are needed and secondly the temperature structure in the marine boundary layer does not follow Monin-Obukhov similarity theory.

Better management of water resources is a growing concern with increasing stress on natural resources. Despite technological improvements in the past decades, a method to instantaneously measure soil water flux remains elusive, especially at a resolution adequate for monitoring natural processes (i.e. 1 mm d-1). The objectives of this research were to evaluate and improve two emerging methods for water flux estimates, 1) streaming potential and 2) heat pulse measurements, as tools to perform at these low flux rates. Streaming potential measures a voltage between two electrodes resulting from water with charged particles generating a current as it flows between the charged surfaces of the soil. Heat pulse measurements, performed with a penta-needle heat pulse probe (PHPP), measure the transport rate and direction of a heat pulse as it propagates from a central needle to surrounding thermistors through soil. Water moving past this sensor carries heat and this allows estimation of water flux from measured heat flux. Streaming potential experimentation demonstrated a clear voltage response to low flow rates. Unfortunately, inconsistent results coupled with measurement complications – susceptibility to electromagnetic noise, drifting, etc. – led to difficulties when trying to establish a congruent relationship between flow rate and voltage behavior. We concluded that the necessary steps to potentially improve measurement consistency made streaming potential less desirable to pursue compared to other emerging tools for water flux measurements. Heat pulse work focused on modifying design parameters to improve low flux rate determination. We tested the effect of increasing heater needle diameter (from 2 mm to 5 mm), increasing heating time (from 8 to 24 and 40 seconds), and doubling heat input (from 120 W m-1 to 240 W m-1) in saturated sand. Results indicated that using larger heater needles and higher heat input improve flux estimation but increasing heating time resulted in marginal improvement. By using a PHPP with a 5 mm heater needle, 24 second heating time, and 240 W m-1 heating input, fluxes were resolved down to 1 cm d-1. Refinement of calibration procedures and inconsistencies between probes used must be resolved if measurement resolution is to be improved further.

This work is an investigation into the curvature related potential for flux to flow in the radial direction in the back-iron of laminated axial flux machine cores. Analytical and numerical models are presented. Analysis based on these models has shown that, in practical axial flux machines, the radial component of the flux density can be neglected with respect to the flux density distribution in the core back-iron. It has also been found that if the core permeability, core conductivity and number of poles are sufficiently high then power loss due to curvature related cross-lamination flux is negligible compared to normal eddy current losses. A closed form expression to predict losses due to curvature related radial flux is also presented. This expression allows axial flux machine designers to make quick assessment of the need to consider these losses when designing axial flux machines.

<p>This report presents a model to determine the solar Extreme UltraViolet (EUV) intensity and the ion flux in the vicinity of Saturn, by using measurements from the Langmuir probe, a plasma investigation instrument, of the Cassini satellite. The model is based on in situ measurements and does therefore provide an improved estimation of the wanted parameters compared to previously used calculations based only on the EUV flux measured near Earth. The solar EUV and ion flux were determined by analysing and processing the current measurements from the Cassini Langmuir probe in several steps. Initially the time intervals where the measured current were expected to be due only to the photoelectron current was extracted. The photoelectron current is the part of the measured probe current that is only due to electrons ejected from the probe by photons coming from the Sun. The measurements showed a periodic behaviour which was concluded to be due to the attitude of the satellite. This interfering effect was corrected for and the data was then plotted against an EUV index, estimated from a traditionally used proxy of the EUV flux near Earth; the F10.7 solar radio flux index. In agreement with the theory of the photoelectric effect a linear relationship between the EUV flux and the photoelectron current <em>m_ph</em> was expected. A least square linear fit to the extracted photoelectron current data provided the relation, for the Langmuir probe on Cassini, in the form of the equation <em>m_ph</em>=0.1842<em>EUV</em>+0.2405, where <em>m_ph</em> is the photoelectron current in nA and <em>EUV</em> is the EUV index in W/Hzm^2. The derived equation is the result of the study, showing how to estimate the solar EUV flux using the Langmuir probe current measurements. This result was used to derive the other wanted parameter, the ion flux. The derivation was done by calculating the photoelectron current <em>m_ph </em>at all time and subtracting the result from the total current. The retrieved difference gives the magnitude of the ion current for every measurement.</p>