The thesis describes problematics of synchronous motor with permanent magnets. The design is provided by analytic and empiric procedures. The great accent is placed on the description of the magnetic circuit of the motor. The finite element method analysis of designed motor is performed subsequently. The main target of this thesis is to find the way, how the ferrite permanent magnet should be used in synchronous motor.

This thesis deals with design of optimal parameters of a relative displacement sensor, working on the electrodynamics principle. The sensor is based on the voltage induction to the coil placed in changing magnetic field. Thesis is divided into three parts: introductory, theoretical and practical. The introductory part provides basic relationships between displacement, velocity and acceleration sensors. The theoretical part contains physical concepts and describes relationships necessary for calculations and creating a model of permanent magnet in COMSOL Multiphysics. In thesis further presents patent research of electrodynamic sensors. The practical part describes the creation of the permanent magnet model and the subsequent calculation of the induced voltage in the coil in Matlab. A description of laboratory measurements follows, presenting the final comparison of the simulation and measurement results. There were found some differences, which might have been caused by incorrect calculation of the induced voltage. The final part of the thesis presents general recommendations for the design of sensor, resulting from simulations and measurements.

In this thesis different methods of optimizing line start permanent magnet motor (LSPM) for magnet cost reduction is studied. Influence of different parameters has been studied by simulating magneto-static and transient FEM models of the machine. Finally a motor design of a LSPM with high rotor saliency has been proposed. The first method investigated is the use of flux barriers in LSPM and its effect on the magnetic flux leakage. The flux barriers reduce the flux leakage and hence help in reducing magnet volume. The second method studied is the use of two different grades of magnets. Using low price magnets help in reducing the total magnet cost without reducing the air gap flux density. The reduction in NdFeB magnet volume is not substantial by using both the methods mentioned above. The third method investigated is increasing the saliency of the rotor by introducing flux barriers and reducing the corresponding magnet volume. Both the magneto static and transient models are used to study the effect of different parameters of the motor. The placement and volume of magnet plays a critical role in motor performance. At first, the developed reluctance torque of the motor is maximized by doing parametric study and then magnets are placed in slots to achieve the required efficiency and power factor. The motor is simulated with NdFeB magnets and with Ferrite magnets. It has been found that using high saliency LSPM motor the NdFeB magnet volume can be reduced significantly. It is also shown that the same performance of motor (as compared to the motor with NdFeB magnets) can be achieved by using Ferrite magnets. The volume of Ferrite magnet required will be larger but still cost-wise using Ferrite is an attractive choice. Therefore, a design of motor is proposed using both NdFeB magnets and Ferrite magnets. Finally, the performance of proposed LSPM motor with high saliency is compared with that of an induction motor.

The number of people suffering from neurodegenerative diseases, such as Alzheimer`s disease, increased dramatically over the past centuries and is expected to increase even further within the next years. Based on predictions of the World Health Organization and Alzheimer`s Disease International, 115 million people will suffer from dementia by the year 2050. An additionally increase in other age related neurodegenerative diseases is also forecasted. Quite naturally, neurodegenerative diseases became a focus of attention of governments and health insurances, trying to control the uprising financial burden. Early detection and treatment of neurodegenerative diseases could be an important component in containing this problem. In particular, researchers focused on automatic methods to analyze patients’ imaging data. One way to detect structural changes in magnetic resonance images (MRI) is the voxel-based method approach. It was specifically implemented for various imaging modalities, e.g. T1-weighted images or diffusion tensor imaging (DTI). Voxel-based morphometry (VBM), a method specifically designed to analyze T1-weighted images, has become very popular over the last decade. Investigations using VBM revealed numerous structural brain changes related to, e.g. neurodegeneration, learning induced structural changes or aging. Although voxel-based methods are designed to be robust and reliable structural change detection methods, it is known that they can be influenced by physical and physiological factors. Dehydration, for example, can affect the volume of brain structures and possibly induce a confound in morphometric studies. Therefore, three-dimensional T1-weighted images were acquired of six young and healthy subjects during different states of hydration. Measurements during normal hydration, hyperhydration, and dehydration made it possible to assess consequential volume changes in gray matter (GM), white matter (WM), and cerebrospinal fluid (CSF). The datasets were analyzed using VBM, FreeSurfer and SIENA. A significant decrease of GM and WM volume, associated with dehydration, was found in various brain regions. The most prominent effects were found in temporal and parietal areas, in the left inferior orbito-frontal region, and in the extra-nuclear region. Moreover, we found consistent increases in CSF, an expansion around 6% of the ventricular system affecting both lateral ventricles, i.e. the third and fourth ventricle. Similar degrees of shrinkage in WM volume and increase of the ventricular system have been reported in studies of Alzheimer’s disease during disease progression and in its prestage mild cognitive impairment. Based on these findings, a potential confound in GM and WM or CSF studies due to the subjects’ hydration state cannot be excluded and should be appropriately addressed. These results underline the sensitivity of VBM and might also concern other voxel-based methods, such as Tract-Based Spatial Statistics (TBSS). TBSS was specifically designed for WM analyses and its sensitivity might be helpful for revealing the spatial relation of structural WM changes and related blood serum biomarkers. Two common brain related biomarkers are the glial protein S100B, a plasticity inducing neuro- and gliotrophin, and neuron-specific enolase (NSE), a marker for neuronal damage. However, the spatial specificity of these biomarkers for brain region has not been investigated in vivo until now. Therefore, we acquired two MRI parameters – T1- weighted and DTI - sensitive to changes in GM and WM, and obtained serum S100B and NSE levels of 41 healthy subjects. Additionally, the gene expression of S100B on the whole brain level in a male cohort of three subjects from the Allen Brain Database was analyzed. Furthermore, a female post mortal brain was investigated using double immunofluorescence labeling with oligodendrocyte markers. It could be shown that S100B is specifically related to white matter structures, namely the corpus callosum, anterior forceps and superior longitudinal fasciculus in female subjects. This effect was observed in fractional anisotropy and radial diffusivity – the latest an indicator of myelin changes. Histological data confirmed a co-localization of S100B with oligodendrocyte markers in the human corpus callosum. S100B was most abundantly expressed in the corpus callosum according to the whole genome Allen Human Brain Atlas. In addition, NSE was related to gray matter structures, namely the amygdala. This effect was detected across sexes. The data demonstrates a very high S100B expression in white matter tracts, in particular in human corpus callosum. This was the first in vivo study validating the specificity of the glial marker S100B for the human brain, and supporting the assumption that radial diffusivity represents a myelin marker. The results open a new perspective for future studies investigating major neuropsychiatric disorders. All above mentioned studies are mainly dependent on the sensitivity and accuracy of soft and hardware parameters. In particular, technical developments have improved acquisition accuracy in the field of MRI. Interestingly, very little is known about the confounding effects of variations due to hardware parameters and their possible impact on reliability and sensitivity of VBM. Recent studies have shown that different acquisition parameters may influence VBM results. Therefore age-related GM changes were investigated with VBM in 36 healthy volunteers grouped into 12 young, 12 middle-aged and 12 elderly subject. Six T1-weighted datasets were acquired per subject with a 12-channel matrix coil, as well as a 32-channel array, MP-RAGE and MP2RAGE, and with isotropic resolutions of 0.8 and 1 mm. DARTEL-VBM was applied on all images and GM, WM and CSF segments were statistically analyzed.. Paired t-tests and statistical interaction tests revealed significant effects of acquisition parameters on the estimated gray-matter-density (GMD) in various cortical and subcortical brain regions. MP2RAGE seemed slightly less prone to false positive results when comparing data acquired with different RF coils and yielded superior segmentation of deep GM structures. With the 12-channel coil, MP-RAGE was superior in detecting age-related changes, especially in cortical structures. Most differences between both sequences became insignificant with the 32-channel coil, indicating that the MP2RAGE images benefited more from the improved signal-to-noise ratio and improved parallel-imaging reconstruction). A possible explanation might be an overestimation of the GM compartment on the MP-RAGE images. In view of substantial effects obtained for all parameters, careful standardization of the acquisition protocol is advocated. While the current investigation focused on aging effects, similar results are expected for other VBM studies, like on plasticity or neurodegenerative diseases. This work has shown that voxel-based methods are sensitive to subtle structural brain changes, independent of imaging modality and scanning parameters. In particular, the studies investigated and discussed the analysis of T1- and diffusion weighted images with VBM and TBSS in the context of dehydration, blood serum sensitive biomarkers and aging were discussed. The major goal of these studies was the investigation of the sensitivity of voxel-based methods. In conclusion, sensitivity and accuracy of voxelbased methods is already high, but it can be increased significantly, using optimal hardand software parameters. It is of note, though, that these optimizations and the concomitant increase of detection sensitivity could also introduce additional confounding factors in the imaging data and interfere with the latter preprocessing and statistical computations. To avoid an interference e.g. originating from physiological parameters, a very careful selection and monitoring of biological parameters of each volunteer throughout the whole study is recommended. A potential impact of scanning parameters can be minimized by strict adherence to the imaging protocol for each study subjectwithin a study. A general increase in detection sensitivity due to optimized parameters selection in hard- and/or can not be concluded by the above mentioned studies. Although the present work addressed some of those issues, the topic of optimal selection of parameters for morphometric studies is still very complex and controversial and has to be individually decided. Further investigations are needed to define more general scanning and preprocessing standards to increase detection sensitivity without the concomitant amplification of confounding factors.

This thesis is a study on an unconventional slow speed direct drive permanent magnet (PM) generator. Unlike a standard permanent magnet synchronous generator (PMSG) which has the copper coils wound around iron teeth, the work in this thesis will present a generator where the copper coils are directly mounted on the stator which eliminates the slots and teeth in the generator. By having a slotless design it is possible to eliminate cogging torque, iron losses in teeth and achieve a lightweight design. These characteristics can prove useful when developing generators for an application such as wind turbines, or more specifically vertical axis wind turbines (VAWTs) in remote areas where weight and serviceability is of concern. This thesis consists of two main parts where the main focus was on the design and simulation of slotless generators. The second part of the thesis was to investigate an available slotless axial flux machine. For the simulations, three different models were created in 2D using CAD software. Two of the models were double-rotor slotless generators and one was a single rotor variant. The electromagnetic properties of these models were analysed using FEMM and COMSOL. The results showed that the double rotor variant with the smaller magnets were more favourable considering the price of magnets and no iron core losses. The experimental results of the axial flux machine gave insight into the construction of commercially available axial slotless generators which could be used to further analyse these types of machines.

La raréfaction de l'hélium utilisé pour le refroidissement des aimants supraconducteurs pousse les fabricants d'aimants supraconducteurs à se tourner vers d'autres types de supraconducteurs performants qui peuvent être employés et refroidis par conduction solide; C'est le cas du MgB₂ . Découvert en 2001, sa température critique (39 K), sa production en série sous différentes formes (rubans, câbles, films etc…) sur de grandes longueurs permettent d'envisager une utilisation à un prix compétitif dans les aimants en remplacement des supraconducteurs basses températures historiques que sont le NbTi et le Nb₃Sn.Cependant, les conducteurs en MgB₂doivent encore être améliorés notamment leur tenue mécanique par rapport aux conducteurs en NbTi et leurs performances réelles à hauts champs doivent encore être démontrées dans les applications concrètes.Cette thèse a pour but le dimensionnement et la fabrication d'un prototype d'aimant MgB₂ refroidi par conduction solide générant un champ au centre de 2 T dans un champ de fond de 3 T. Trois longueurs de conducteur ont du être soudées par deux jonctions résistives au centre du bobinage complexifiant la fabrication du prototype. La thèse s'articule autour de trois axes structurant. Tout d'abord, des caractérisations des performances supraconductrices et mécaniques de différents conducteurs en MgB₂ permettent de sélectionner le conducteur utilisé pour le bobinage du prototype. Ensuite, le dimensionnement du prototype est présenté : calculs mécaniques, thermiques, magnétiques et thermalisation de l'aimant sans oublier la protection. Après la phase de dimensionnement, les étapes nécessaires à la fabrication du prototype (bobinage,imprégnation, mise en place de l'instrumentation et des systèmes de thermalisations) sont détaillées. Afin de valider les étapes précédentes et les performances du prototype, la thèse se termine par une présentation et une analyse des résultats des tests effectués sur le prototype. / Helium shortage is an issue for superconducting magnets and drives superconducting magnet designer to find other types of effective superconductors that could be used in conduction-cooled magnets.MgB₂ is a promising superconducting material and could fill the demand. MgB₂ was discovered in2001, its critical temperature (39 K) as well as its mass production of a variety of shapes (ribbons, films, cables, wires…) over long length makes MgB₂ a competitive substitute to historical low temperature superconductors such as NbTi and Nb₃Sn in magnets. Although promising, MgB₂ conductors still need mechanical improvement compared to NbTi's and their performance in practical applications has yet to be demonstrated especially for low bending radius magnets. This thesis aims to design and builda MgB₂ conduction-cooled prototype generating a 2 T on the axis on its own in a 3 T background field. Three lengths of conductors were fused by two resistive junctions at the very heart of the winding challenging the design and the fabrication because of the thermal issues. The thesis focuses on three main topics. First, superconducting and mechanical performances of several MgB₂ conductors candidates for the prototype are analyzed and discussed. The design calculation (magnetic, mechanical,thermalization of the prototype and protection) and all the fabrication process (winding, instrumentation, thermal apparatus and impregnation) are presented. In order to validate the fabrication steps and the performances of the prototype, the protoype is tested and the results discussed in the last chapter.

Elektronová spinová rezonance (ESR) je neinvazivní spektroskopická technika založená na magnetické rezonanci. Používá se v mnoha vědních oborech jako biologie, chemie a fyzika pro zkoumání systémů s nepárovými elektrony. Tato dizertační práce se věnuje spektroskopii vysokofrekvenční rezonance spinů elektronů (HF-ESR) a jejímu použití na paramagnetické koordinační sloučeniny. V první části je představen teoretický základ s rešerší literatury v této oblasti a jsou představeny aplikace HF-ESR. Dále jsou představeny metody použité ke studování těchto systémů. Zde jsou popsány doplňující metody (XPS, RS, UV-VIS, AFM, SEM) pro zkoumání vzorků a je představen návrh nové sublimační komory vysokého vakua, která byla sestavena pro tvorbu tenkých vrstech koordinačních sloučenin na površích. Následují výsledky dosažené pomocí HF-ESR na molekulárních kvantových bitech [Cu(dbm)2], jednomolekulárních magnetech [CoX2(dppf)], [Co(4MeO-L)2Cl2] a je nastíněna vize bolometrů na bázi grafenu pro detekci této třídy sloučenin. Výsledky jsou diskutovány a jejich implikace jsou shrnuty v závěru. Reference a autorské výstupy pak uzavírají celou tuto práci.

The whiteboard is a tool being used in several different facilities around the world. However, erasing the ink off the board can be unnecessarily time consuming and distracting. The purpose of the project was therefore to create a demonstrator to automate the process with a few restrictions. The demonstrator was required to be light enough and small enough to be handheld. In addition, the demonstrator needed to function and work properly on a magnetic surface. To conceptualize the purpose a demonstrator was built with an iterative process and thereafter programmed to get a systematic movement. It utilized continuous servo motors, IR-sensors and a 3-axis gyroscope and an accelerometer in combination with 3D-printed components. The final prototype turned out to function properly but could be improved as its erasing properties are not working as one could expect from a finished prototype. / Whiteboard är ett verktyg som används i flera olika fastigheter runt om i världen. Att ta bort bläcket från whiteboarden kan dock vara onödigt tidskrävande och distraherande. Syftet med projektet var därför att automatisera processen med några begränsningar. Två begränsningar var att prototypen skulle väga lite och vara tillräckligt liten för att vara handhållen. En annan begränsning var att den skulle fungera korrekt på en magnetisk yta. För att konceptualisera syftet byggdes en prototyp med en iterativ process och därefter programmerades den för att få en systematisk rörelse. Den utnyttjade kontinuerliga servomotorer, IR-sensorer och ett 3-axligt gyroskop i kombination med 3D-printade komponenter. Den slutgiltiga prototypen visade sig fungera korrekt men kan förbättras eftersom dess raderingsegenskaper inte fungerar som man kunde ha förväntat sig från en färdig prototyp.

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