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In recent years, researchers have increasingly used magnetic resonance imaging (MRI) to study temporal skeletal muscle changes using gradient echo (GRE) echo planar imaging (EPI). These studies, typically involving exercise or ischemic challenges, have differentiated healthy subjects from athletic or unhealthy populations, such as those with peripheral vascular disease. However, the analysis methodologies have been lacking. In this thesis, two sessions of post-exercise GRE EPI data were collected from six subjects' lower legs using a 3 Tesla MRI scanner and a custom built ergometer. Past studies used common medical imaging software for motion correction. This work shows that such tools degrade leg image data by introducing motion, increasing root mean squared error in rest data by 22%. A new approach decreased it by 12%. EPI distortion correction in muscle images was also achieved, with the correlation ratio of functional and structural images increasing by up to 8%. In addition, a brief but intense artifact in GRE EPI muscle images results from muscle tissue moving in and out of the imaged volume. This through-plane artifact was successfully modelled as a mono-exponential decay for regression analysis, increasing the utility of the residual signal. The regression parameters were also leveraged to produce muscle displacement maps, identifying 44% of voxels as displaced. The maps were validated in a motion phantom and in-vivo using ultrasound. Finally, independent component analysis (ICA) was applied to post-exercise GRE EPI images to detect features in a data-driven, multivariate way and improve on conventional ROI selection methods. ICA produced parametric maps that were spatially correlated to working muscles from every trial (most with |R| > 0.4). The components were also separated from the susceptibility, motion, and blood vessel signals, and temporally reliable within individuals. These methodological advances represent increased rigour in the analysis of muscle GRE EPI images. / Thesis / Doctor of Philosophy (PhD) / Adequate blood circulation to muscles is important for good health. Researchers have used magnetic resonance imaging (MRI) techniques to assess blood and oxygen supply to muscles. The work in this thesis improves upon the analysis methods in prior work, especially in the areas of motion correction of the images and selection of individual muscle regions for analysis. Previous techniques could sometimes make motion in muscle images worse. This work provides valuable motion and distortion correction for muscle imaging, ensuring that measurements truly reflect muscle physiology. It also describes a method to remove an unwanted signal from post-exercise muscle data, and create a map of the internal muscle motion that occurred. Finally, an advanced mathematical technique was used to extract signals of interest and important spatial features from muscle image data automatically. The technique produced reliable results within and among subjects.

This thesis aims at a deeper understanding of Supercritical Fluid Chromatography (SFC). Although preparative SFC has started to replace Liquid Chromatography (LC) in the pharmaceutical industry - because of its advantages in speed and its less environmental impact - fundamental understanding is still lacking. Therefore there is no rigid framework to characterize adsorption or to understand the impact of changes in operational conditions.   In Paper I we demonstrated, after careful system verification, that most methods applied to determine adsorption isotherms in LC could not be applied directly in SFC. This was mainly due to operational differences and to the fact that the fluid is compressible which means that everything considered constant in LC varies in SFC.   In Paper II we showed that the most accurate methods for adsorption isotherm determination in LC, the so called plateau methods, do not work properly for SFC. Instead, methods based on overloaded profiles should be preferred.   In Paper III a Design of Experiments approach was successfully used to quantitatively describe the retention behavior of several solutes and the productivity of a two component separation system. This approach can be used to optimize SFC separations or to provide information about the separation system.   In Paper IV severe peak distortion effects, suspected to arise from injection solvent and mobile phase fluid mismatches, were carefully investigated using experiments and simulations. By this approach it was possible to examine the underlying reasons for the distortions, which is vital for method development.   Finally, in Paper V, the acquired knowledge from Paper I-IV was used to perform reliable scale-up in an industrial setting for the first time. This was done by carefully matching the conditions inside the analytical and preparative column with each other. The results could therefore provide the industry with key knowledge for further implementation of SFC. / This thesis aims at a deeper understanding of Supercritical Fluid Chromatography (SFC). Although preparative SFC has started to replace Liquid Chromatography (LC) in the pharmaceutical industry - because of its advantages in speed and its less environmental impact - fundamental understanding is still lacking. Therefore there is no rigid framework to characterize adsorption or to understand the impact of changes in operational conditions.   In Paper I-II it was demonstrated why most methods applied to determine adsorption isotherms in LC could not be applied directly for SFC. Methods based on extracting data from overloaded profiles should be preferred.   In Paper III a Design of Experiments approach was successfully used to quantitatively describe the behavior of several solutes in a separation system. This approach can be used to optimize SFC separations or to provide information about the separation system.   In Paper IV severe peak distortion effects often observed in SFC were carefully investigated and explained using experiments and simulations.   Finally, in Paper V, the prerequisites for performing reliable and predictable scale-up of SFC were investigated by small and large scale experiments. / <p>Paper 4 ("Evaluation of scale-up from analytical to preparative...") ingick som manuskript med samma titel i avhandlingen. Nu publicerad. </p>

Encoding hieroglyphic texts is time-consuming. If a text already exists as hand-written transcription, there is an alternative, namely OCR. Off-the-shelf OCR systems seem difficult to adapt to the peculiarities of Ancient Egyptian. Presented is a proof-of-concept tool that was designed to digitize texts of Urkunden IV in the hand-writing of Kurt Sethe. It automatically recognizes signs and produces a normalized encoding, suitable for storage in a database, or for printing on a screen or on paper, requiring little manual correction. The encoding of hieroglyphic text is RES (Revised Encoding Scheme) rather than (common dialects of) MdC (Manuel de Codage). Earlier papers argued against MdC and in favour of RES for corpus development. Arguments in favour of RES include longevity of the encoding, as its semantics are font-independent. The present study provides evidence that RES is also much preferable to MdC in the context of OCR. With a well-understood parsing technique, relative positioning of scanned signs can be straightforwardly mapped to suitable primitives of the encoding.

The resolution power of single Very Low Frequency (VLF) data and multi-frequency Radiomagnetotelluric (RMT) data in delineating conductive structures typical for the sedimentary cover and crystalline basement in Scandinavia is studied with a view to future developments of the technique to increasing the frequency range into the LW radio band. Airborne and ground VLF data are interpreted and correlated with RMT measurements made on the ground to better understand the resolution power of VLF data. To aid in this understanding single and multifrequency VLF and RMT responses for some typical resistivity structures are analyzed. An analytic model is presented for obtaining unique transfer functions from measurements of the electromagnetic components on board an air-plane or on the ground. Examples of 2D inversion of ground and airborne VLF profiles in Sweden are shown to demonstrate the quantitative interpretation of VLF data in terms of both lateral and depth changes of the resistivity in the uppermost crust. Geothermal resources are ideal targets for Electromagnetic (EM) methods since they produce strong variations in underground electrical resistivity. Modelling of Magnetotelluric (MT) data in SW Iceland indicates an alteration zone beneath the surface, where there are no obvious geothermal manifestations, in between Hengill and Brennisteinsfjoll geothermal systems. It suggests that a hydrothermal fluid circulation exists at depth. It also proves that the MT method, with its ability to map deep conductive features can play a valuable role in the reconnaissance of deep geothermal systems in active rift regimes such as in Iceland. A damped nonlinear least-squares inversion approach is employed to invert Controlled Source Tensor MT (CSTMT) data for azimuthal anisotropy in a 1D layered earth. Impedance and tipper data are inverted jointly. The effects of near-surface inhomogeneities are parameterized in addition to each layer parameter(s). Application of the inversion algorithm to both synthetic and field data shows that the CSTMT method can be used to detect azimuthal anisotropy under realistic conditions with near surface lateral heterogeneities.

Oberschwingungen als ein Merkmal der Elektroenergiequalität gewinnen durch die starke Netzintegration leistungselektronisch geregelter Anlagen wie Windenergieanlagen und nichtlineare Lasten zunehmend an Bedeutung. Bestehende Normen entsprechen nicht den zukünftigen Erfordernissen des Elektroenergiesystems und bedürfen diesbezüglich einer Überarbeitung. In der Arbeit werden wesentliche Einflussfaktoren auf das Oberschwingungsverhalten von Windparks identifiziert, beschrieben und modelliert. Dabei wird der stochastische Charakter der Oberschwingungen mithilfe von probabilistischen Ansätzen erfasst. Des Weiteren wird ein neuer Ansatz zur Untersuchung der Wechselwirkung zwischen dem Windpark und dem vorgelagerten Netz entwickelt. Der Ansatz ermöglicht, die vom Windpark verursachte Änderung der Oberschwingungsspannung am Netzanschlusspunkt zu ermitteln. Diese Arbeit liefert einen Beitrag zur Verbesserung bestehender Normen für die Anbindung von Windparks. / Harmonics, as one of the power quality criteria, are increasingly gaining attention due to the progressive contribution of renewable energy resources and the application of the nonlinear load in the power system. Current standards do not conform to the future requirements of the power system, thus requiring a revision. In this work, main influence factors on the harmonic behavior of wind farms are identified, explained, and modelled. Thereby, the stochastic nature of harmonics is taken into account using probabilistic approaches. Moreover, a novel approach is developed to investigate the interaction between the wind farm and the upstream grid. With the aid of this approach, it is possible to determine the voltage change caused by the wind farm at the point of connection. This work contributes to improve the existing standards for the connection of wind farms.

Proliferation of non-linear, single-phase power electronics loads, such as personal computers, television sets, CFLs, has resulted in thousands of individual small harmonic current injectors connected to a distribution feeder network. Harmonic standard: IEC 1000-3-2 classifies such loads as Class D, “low-voltage” equipment with current emissions limited to 16A/Phase. Individual harmonic contributions of such loads appear insignificant; their collective contribution, however, is a matter of concern. The average order of voltage distortion usually varies between 4-6%; current distortion, however, is usually of the order of 100%. Limitations and high-costs associated with conventional harmonic mitigation measures, has furthered the need for regulation and alternative strategies. The objective of this research is to predict, and mitigate the effects of harmonic proliferation in the main supply current measured at the point of common coupling (PCC). An equivalent circuit model – an aggregation of single phase power electronics loads connected to the distribution feeder network is proposed as a part of a forward solution. Each load, individually, behaves as a harmonic current source; the proposed model combines these individual harmonic current injectors into a single harmonic source connected at the PCC and their collective contribution as a single composite harmonic signal. It represents harmonic conditions at the PCC and provides a theoretical measure of harmonic distortion in the supply current. Such a model finds application during harmonic compliance testing for single-phase power electronics loads; it simulates and predicts the harmonic response of such loads using a theoretical pure 60 Hz sine wave as the supply voltage diffcult to obtain physically, yet critical to such tests. The accuracy of the equivalent circuit model in predicting a harmonic response is pivotal to a successful forward solution. A feed-backwards mechanism is proposed. For a given harmonic supply voltage and circuit configuration of the equivalent circuit model, the feed-backwards method generates the modeled response and compares it to a reference physical response. Finally, it optimizes the circuit configuration to a unique Correction Factor that facilitates an accurate modeled response. Three optimization algorithms, labeled as Response Optimization algorithms have been developed to execute the feed-backwards mechanism. These algorithms are written in FORTRAN-90. / text

Dans cette thèse, les recherches ont été menées à des niveaux d'abstraction différents pour optimiser le fonctionnement du modulateur ΣΔ passe-haut (PH). Une approche « top-down » est adoptée pour atteindre cet objectif. Au niveau de l'architecture du récepteur RF, le nouvellement créé récepteur Fs/2 est sélectionné pour sa grande compatibilité avec modulateur ΣΔ PH comparé aux architectures de réception: zéro-IF et faible-IF. Après avoir défini la topologie du récepteur, l'architecture du modulateur ΣΔ est adressée. Nous proposons une nouvelle architecture du deuxième ordre dont la fonction de transfert du signal est unitaire. Elle est plus avantageuse que d'autres topologies en termes de complexité et de performance. Puisque le modulateur de second ordre est incapable de fournir les performances requises, les structures en cascade ou MASH pour l'opération PH sont explorées. La topologie GMSCL (Generalized Multi-Stage Closed Loop) est choisie et une technique récemment proposée est appliquée pour linéariser le CNA de retour. En plus, cette technique augmente la plage dynamique du convertisseur. Ensuite, après une analyse comparative approfondie, le meilleur filtre HP est choisie pour ce modulateur. Il a les avantages d'avoir une basse consommation, une superficie réduite et un bruit moins important. Enfin, l'architecture GMSCL PH proposée est validée en CMOS 65nm. Les applications visées sont l'UMTS avec 3.84MHz bande de conversion à 80 dB de la plage dynamique et WiMAX avec 25MHz de bande passante à 52dB de dynamique.

<p>Quality of the castings is affected by several factors which the designer should take into consideration during the product development process. Although residual stress is one of those, it is often not considered in practical computations. Hence residual stresses are one of the forgotten areas in designing of machine parts. This master thesis is focused on the investigation of residual stresses in a high pressure die casted component, with the aim of extending its service life, by taking results from the study as a feedback.</p><p>The investigation of residual stresses was done on a variety of specimens, cast aluminum flywheel, provided by Husqvarna AB. This flywheel is a component in a product of the same company.In evaluating the residual stresses in the part, two tools-simulation and physical measurement were used. Moreover, comparison with these two methods is also done at an area of interest on the flywheel. The simulation was carried out by using MAGMAhpdc-a module for high pressure die casting process, from the commercial software package MAGMAsoft; while for the physical measurements, the hole drilling method was used, a method believed to be less accurate at low stresses areas.</p><p>The findings obtained from this study show that the results from both procedures are close, with small deviations observed, which reveals the reliability of the hole drilling method even when the stress levels are low. It is also found that the compressive residual stresses dominate in the component-a preferred phenomenon with regards to residual stress.</p>

La scoliose idiopathique de l’adolescence (SIA) est une déformation tridimensionnelle de la colonne vertébrale et de la cage thoracique dont la cause est inconnue. Il semble que la ceinture pelvienne soit impliquée dans la pathogénie de la SIA, car des différences géométriques des os coxaux ont été observées. Notamment, une rotation du bassin ou une inclinaison latérale dans le sens de la courbe scoliotique ont été mises en évidence en plus des distorsions osseuses. Il est difficile de dissocier la rotation du bassin de son asymétrie, car la majorité des études porte sur des données radiologiques bidimensionnelles. Une analyse tridimensionnelle de la morphologie du bassin de patientes ayant une SIA, mais n’ayant pas reçu de traitement par corset ou chirurgie permettrait d’identifier le rôle du bassin dans la progression de la scoliose. Dix-sept jeunes filles atteintes de la SIA ont participé à cette étude pour lesquelles des radiographies bi-planaires en station debout étaient disponibles au moment du diagnostic par un chirurgien orthopédiste pédiatrique et à l’instant de la prescription d'un corset. Des radiographies postéro-antérieures et latérales avaient été prises au moyen du système EOS®. Douze repères anatomiques du bassin ont été identifiés sur les paires de radiographies, alors que quatre repères ont été identifiés sur la radiographie postéro-antérieure uniquement. Ces quatre derniers n’étaient pas identifiables sur la radiographie latérale à cause de la superposition des repères droits et gauches. La reconstruction tridimensionnelle du bassin a été réalisée à partir de deux clichés radiographiques des 12 premiers repères osseux. Au total, neuf paramètres tridimensionnels ont été calculés afin de quantifier l’asymétrie et la distorsion du bassin entre les deux temps donnés. Des paramètres bidimensionnels ont également été mesurés sur les quatre derniers repères osseux afin de documenter des déformations du bassin pertinentes à la pratique clinique, telle que la rotation axiale de celui-ci. Dans le but d'évaluer une possible asymétrie entre les os coxaux du bassin, les paramètres tridimensionnels du bassin gauche ont été comparés à ceux du côté droit à chaque temps, au moyen d'un test-t pour échantillon apparié. La morphologie pelvienne a été également évaluée par l'analyse multivariée (MANOVA) à mesures répétées à deux conditions (côté*temps). En conséquence, nous avons constaté une croissance osseuse statistiquement significative du bassin dans l’intervalle de temps entre le diagnostic de la scoliose et le port du corset (p=0,033). Une asymétrie significative entre les côtés gauche et droit du bassin (p=0,013) a également été constatée. En ce qui concerne les paramètres bidimensionnels, nous avons constaté une augmentation de la version pelvienne (p=0,024) au cours de la croissance des jeunes filles. Finalement, le bassin n'a pas présenté de distorsion, puisqu'une valeur de p de 0,763 a été observée. En conclusion, la croissance des jeunes filles atteintes de la scoliose idiopathique de l'adolescence est accompagnée d'une asymétrie morphologique entre les deux os coxaux du bassin. Cette asymétrie constatée au moment du diagnostic de la scoliose des filles a évolué jusqu'à l’instant où le port du corset a été prescrit. Quant aux paramètres bidimensionnels, nous pouvons conclure que la rotation du bassin vers l'arrière a augmenté au cours de la croissance des jeunes filles, produisant ainsi une rétroversion pelvienne dans le plan sagittal. La distorsion tridimensionnelle du bassin n'a toutefois pas été observée au cours de la croissance des jeunes filles. / Adolescent idiopathic scoliosis (AIS) is a three-dimensional deformation of the spine and rib cage of unknown cause. It seems that the pelvis is involved in the pathogenesis of the AIS because geometric differences in the hip bones were observed. A pelvic rotation or a lateral tilt in the direction of the scoliotic curve was observed in addition to bone distortions. It is difficult to separate the pelvic rotation from its asymmetry since most studies are based on bi-dimensional radiologic data. A three-dimensional analysis of the pelvis morphology in patients with AIS, but no brace treatment nor surgery could better define the role of pelvis in the progression of the scoliosis. Seventeen young girls with AIS have participated in this study. Standing bi-planer radiographs were available at the time of diagnosis by a pediatric orthopedic surgeon and at the moment of the brace prescription. Postero-anterior and lateral X-rays were taken using the EOS® system. Twelve anatomical landmarks of the pelvis were identified on the radiograph pairs and four landmarks were identified on the postero-anterior radiography only. These were not identified on the lateral radiograph due to the superposition of the right and left landmarks. The three-dimensional reconstruction of the pelvis was performed using two radiographs of the first 12 bony landmarks. A total of nine three-dimensional parameters were calculated to quantify the asymmetry of the pelvis distortion between the two given times. Bi-dimensional parameters were also measured on the last four bony landmarks in order to document the pelvic deformations relevant to the clinical practice such as the rotation. With the objective of evaluating a possible asymmetry between the hip bones of the pelvis, the three-dimension parameters of the left pelvis were compared to those of the right side in each time using a paired sample t-test. The pelvic morphology was also evaluated using a multivariate analysis (MANOVA) with repeated measures on two conditions (side*time). A statistically significant bone growth of the pelvis in the time interval between the diagnosis of the scoliosis and the brace prescription (p=0.033) was observed in consequence. A significant asymmetry between the left and right sides of the pelvis (p=0.013) without distortion was also observed. Regarding the bi-dimensional parameters, we found an increase in pelvic release (p=0.024) during the growth of the girls. Finally, the pelvis did not show a distortion because a p value of 0.763 was observed. In conclusion, the growth of young girls with adolescent idiopathic scoliosis is related to a morphological asymmetry between the two hipbones of the pelvis. This asymmetry observed at the moment of the scolioisis diagnosis has evolved until de moment of the brace prescription. As for the bi-dimensional parameters, we can conclude that the rotation of the pelvis to the back increased during the growth of the girls, producing a pelvic retroversion in the sagittal plan. The three-dimensional distortion of the pelvis, however, has not been observed during the young girls growth.