Sr₃Ru₂O₇ is a quasi-two-dimensional metal and has a paramagnetic ground state that is heavily renormalised by electron-electron correlations and magnetic exchange interactions. Inextricably linked to this renormalisation is the metamagnetism of Sr₃Ru₂O₇ - a rapid rise in uniform magnetisation over a narrow range of applied magnetic field. Knowledge of the zero-field physics is essential to any description of the metamagnetism. Light may be shed on the enigmatic ground state of Sr₃Ru₂O₇ by doping the crystal lattice with foreign cations: this is the primary purpose of the original research referred to in this thesis, in which studies of some of the electronic properties of crystals of cation-doped Sr₃Ru₂O₇ are reported. Single crystals of Sr₃(Ru[subscript(1-x)]Ti[subscript(x)])₂O₇ and Sr₃(Ru[subscript(1-x)]Cr[subscript(x)])₂O₇ have been synthesised in an image furnace and some of the properties of these crystals have been measured. Evidence that indicates the emergence of a spin density wave as a function of Ti-doping in Sr₃(Ru[subscript(1-x)]Ti[subscript(x)])₂O₇ is presented. Time-dependent magnetic irreversibility has been observed in samples of Sr₃(Ru[subscript(1-x)]Cr[subscript(x)])₂O₇, thus hinting at the involvement of the RKKY mechanism in these materials. Regarding cation doping out of the conducting RuO₂ planes, samples of (Sr[subscript(1-y)]La[subscript(y)])₃Ru₂O₇ have been grown and investigated. Both the Sommerfeld coefficient and the Fermi liquid A coefficient of (Sr[subscript(1-y)]La[subscript(y)])₃Ru₂O₇ are found to decrease as a function of y (0 ≤ y ≤ 0.02); these observations point towards a reduction in the thermodynamic mass of the Landau quasiparticles. Results from magnetoresistance and magnetisation measurements indicate that the metamagnetism of the (Sr[subscript(1-y)]La[subscript(y)])₃Ru₂O₇ series probably cannot be explained by a rigid band-shift model. Also, some aspects of these data imply that the metamagnetism cannot be fully accounted for by a spin fluctuation extension to the Ginzburg-Landau theory of uniform magnetisation.

Cette thèse aborde le problème de la calibration d’un ensemble de capteurscomposé d’une centrale inertielle, d’un magnétomètre et d’une caméra, avecpour objectif leur intégration sur un système très compact : un mini-drone.Cette étude expose tout d’abord les contraintes imposées par l’application surle choix des capteurs et les solutions envisagées notamment pour résoudre leproblème de la synchronisation des mesures. Après avoir étudié les techniquesde calibration existantes, une méthode permettant la calibration de l’ensembledes capteurs (accéléromètre, gyromètre, magnétomètre et caméra) est présentée.La solution proposée permet également d’estimer les changements de repèresentre les différents capteurs. Elle a la particularité de ne nécessiter l’emploid’aucun matériel particulier. D’autre part, l’intégration de ces capteurs dans unsystème aussi compact soulève de nouvelles difficultés. Dans ces conditions, leschamps magnétiques créés par les actionneurs du drone perturbent les mesuresdu magnétomètre se trouvant à proximité. Une nouvelle méthode est proposéeafin d’estimer et de compenser dynamiquement ces perturbations magnétiquesen fonction de l’état des actionneurs du drone. Enfin, deux applications dusystème comprenant une centrale inertielle et une caméra sont présentées :la construction de mosaïques d’images géo-référencées et la stabilisation devidéos. Ces deux applications exploitent les mesures des capteurs inertiels afind’effectuer un traitement en temps réel pour un coût calculatoire très faible. / This thesis deal with the issue of the calibration of a group of sensor composedof an inertial unit, a magnetometer and a camera. It aims at integratingthem into a very compact system : a mini-drone. First of all, this study outlinesthe constraints imposed by the application on the choice of the sensors andthe solutions considered to solve the measures synchronization issue. Afterstudying existing calibration techniques, a method for the calibration of allthe sensors (accelerometer, gyroscope, magnetometer and camera) is presented.The proposed solution allows to estimate the frame transformation between thedifferent sensors. It has the advantage of not requiring the use of any specialequipment. Furthermore, the integration of these sensors into a compact systemraises new difficulties. Under these conditions, the magnetic fields created bythe drone actuators disrupt magnetometer measurements. A new method isproposed to estimate and compensate for these magnetic disturbances. Thecompensation is dynamically adapted based on the state of the drone actuators.Finally, two applications of the system including an inertial unit and a cameraare presented : the construction of geo-referenced images mosaic and videostabilization. Both applications use measurements of inertial sensors and precisecalibration to perform a real-time processing for a very low computational cost.

Το θέμα αυτής της διπλωματικής εργασίας είναι η παρασκευή με τη μέθοδο sputtering και ο χαρακτηρισμός μαγνητικών λεπτών υμενίων. Στo πρώτο κεφάλαιο, που αποτελεί και την εισαγωγή, γίνεται μια αναφορά στη τεχνολογία των λεπτών υμενίων και δίνεται το στοιχειώδες θεωρητικό υπόβαθρο των τεχνικών ανάπτυξης αυτών. Στο δεύτερο κεφάλαιο παρουσιάζεται η διάταξη sputtering που χρησιμοποιήθηκε για την ανάπτυξη των μαγνητικών υμενίων και δίνονται τα αποτελέσματα της βαθμονόμησης ενός μετρητικού πάχους υψηλής ακρίβειας. Το τρίτο κεφάλαιο αναφέρεται στην κατασκευή και πιστοποίηση μιας πλήρως αυτοματοποιημένης και χαμηλού κόστους διάταξης μέτρησης μαγνητικών βρόχων μέσω του φαινομένου Kerr, με μέγιστο πεδίο πόλωσης 2Τ. Το τέταρτο κεφάλαιο αναφέρεται στις πειραματικές λεπτομέρειες της παρασκευής των μαγνητικών λεπτών υμενίων Νικελίου και Κοβαλτίου και δίνονται τα αποτελέσματα του δομικού και μαγνητικού χαρακτηρισμού τους. Τέλος, στο πέμπτο κεφάλαιο, παρουσιάζονται τα συμπεράσματα και οι παρατηρήσεις που προέκυψαν κατά τη διάρκεια της ενασχόλησης με τη διπλωματική εργασία. Γίνονται, επιπλέον, και ορισμένες προτάσεις για τη μελλοντική εξέλιξη των συστημάτων sputtering και ΜΟΚΕ, ενώ τονίζεται και το τεχνολογικό ενδιαφέρον που παρουσιάζουν τα υμένια που παρασκευάσθηκαν. / The subject of this diploma thesis is the growth using the sputtering process and the characterization of thin magnetic films. The first chapter refers to thin films' technology and there is given the elementary theoretical background of the thin films’ growth. In the second chapter, there is presented the sputtering device, which is used for the growth of the magnetic films. Also, there is given the results of the calibration of a newly established thickness monitor, which is used for high accuracy thickness measurements. In the third chapter, there is given the description of the construction of a fully automatic and low cost magneto - optic Kerr effect magnetometer for the magnetic loops' measurement in a maximum magnetic field of 2T. There are, also, given the magnetic loops which are used for the construction’s certification. The fourth chapter refers to the experimental details about the preparation of the Nickel and Cobalt magnetic thin films. There are, also, given the results about the structural and magnetic characterization of the thin films. Finally, in the fifth chapter, there are presented the conclusions and the observations, which arose during the diploma thesis. There are, also, presented some proposals about the future progress of the sputtering and MOKE systems, whereas at the same, there is stressed the technical interest of the thin films, which are prepared.

This master's thesis focuses on the utilization of an artificially created weak magnetic field for navigation in 3D space. The theoretical part of this work deals with the general properties of the magnetic field and with its description. The next section of the theoretical part contains an overview of measuring principles for magnetic field measurements. Based on various types of measuring principles, the thesis elaborates on commercially available miniature sensors for magnetic field measurement with a measuring range up to 10 mT. The work focuses mainly on the magnetoresistive principle and fluxgate sensors. Furthermore, the theoretical part contains descriptions of methods for modeling the magnetic field of simple permanent magnets and various magnet assemblies. Lastly, the theoretical part involves a patent search of devices used for locating magnets that are installed in an intramedullary nail, which is used in intramedullary stabilization used on fractures of human bones. By locating the magnet in the nail, it is possible to precisely determine the position of the mounting holes. The practical part of the thesis deals with the analysis of magnetic field behavior in the vicinity of various magnetic assemblies, which were modeled in COMSOL Multiphysics using the finite element method. The models were created with the aim of analysing the behaviour of the magnetic field in the vicinity of the magnets and at the same time to find possible analytical functions that could be used to determine the position of the magnet in space relative to the probe. The result of this work is an analysis of various assemblies, which contains graphs of different dependencies and prescription of polynomial functions that approximate these dependencies. Another part of the thesis is the design of a probe that serves to locate the magnetic target. The work describes two possible methods of localization. For the differential method, a user interface in LabVIEW was created. The probe based on this method is fully capable of locating the magnet in the 2D plane. The state space search method is described only in theory.

This diploma thesis deals with processing of measured data from inertial navigation system in order these could be used for stabilization. There is general information about aerial vehicles called copters with emphasis on four-rotor construction called quadrocopter at first. Then mathematical model of quadrocopter in state space form is derived, the particular implementation of university developed quadrocopter is described and the design of data processing algorithm is presented with measured results. Finally achieved results are discussed.

Conventional resistance spot welds are not visible from the outside. Therefore, it is not straightforward to evaluate the joint quality non-destructively. The pulse-echo method of manual ultrasonic is widely used for non-destructive testing. Another option is the passive magnetic flux density testing, which is being developed at Technische Universität Dresden, Germany. The spot weld is magnetized in the normal direction and the residual magnetic flux density is measured on top of the surface of the joint. This method is suitable for spot welds on typical car body steels. Previous investigations show that the magnetic properties of the materials influence the test result. In order to develop this new non-destructive testing method further, it is necessary to know the magnetic properties of the different microstructure regions of a spot weld. This article focuses on methods to measure and evaluate the magnetic properties of these regions, especially of the base material and the weld. Different measuring methods and approaches are presented and compared with each other. Based on the results, recommendations for future measurements for magnetic characterizations are given.

The advent of unoccupied aerial systems (UAS) as disruptive technology has a lasting impact on remote sensing, geophysics and most geosciences. Small, lightweight, and low-cost UAS enable researchers and surveyors to acquire earth observation data in higher spatial and spectral resolution as compared to airborne and satellite data. UAS-based applications range from rapid topographic mapping using photogrammetric techniques to hyperspectral and geophysical measurements of surface and subsurface geology. UAS surveys contribute to identifying metal deposits, monitoring of mine sites and can reveal arising environmental issues associated with mining. Further, affordable UAS technology will boost exploration data availability and expertise in the global south. This thesis investigates the application of UAS-based multi-sensor data for mineral exploration, in particular the integration of hyperspectral imagers, magnetometers and digital cameras (covering the visible red, green, blue light spectrum). UAS-based research is maturing, however the aforementioned methods are not unified effectively. RGB-based photogrammetry is used to investigate topography and surface texture. Image spectrometers measure mineral-specific surface signatures. Magnetometers detect geomagnetic field changes caused by magnetic minerals at surface and depth. The integration of such UAS sensor-based methods in this thesis augments exploration potential with non-invasive, high-resolution, safe, rapid and practical survey methods. UAS-based surveying acquired, processed and integrated data from three distinct test sites. The sites are located in Finland (Fe-Ti-V at Otanmäki; apatite at Siilinjärvi) and Greenland (Ni-Cu-PGE at Qullissat, Disko Island) and were chosen as geologically diverse areas in subarctic to arctic environments. Restricted accessibility, unfavourable atmospheric conditions, dark rocks, debris and vegetation cover and low solar illumination were common features. While the topography in Finland was moderately flat, a steep landscape challenged the Greenland field work. These restraints meant that acquisitions varied from site to site and how data was integrated and interpreted is dependent on the commodity of interest. Iron-based spectral absorption and magnetic mineral response were detected using hyperspectral and magnetic surveying in Otanmäki. Multi-sensor-based image feature detection and classification combined with magnetic forward modelling enabled seamless geologic mapping in Siilinjärvi. Detailed magnetic inversion and multispectral photogrammetry led to the construction of a comprehensive 3D model of magmatic exploration targets in Greenland. Ground truth at different intensity was employed to verify UAS-based data interpretations during all case studies. Laboratory analysis was applied when deemed necessary to acquire geologic-mineralogic validation (e.g., X-ray diffraction and optical microscopy for mineral identification to establish lithologic domains, magnetic susceptibility measurements for subsurface modelling), for example for trace amounts of magnetite in carbonatite (Siilinjärvi) and native iron occurrence in basalt (Qullissat). Technical achievements were the integration of a multicopter-based prototype fluxgate-magnetometer data from different survey altitudes with ground truth, and a feasibility study with a high-speed multispectral image system for fixed-wing UAS. The employed case studies transfer the experiences made towards general recommendations for UAS application-based multi-sensor integration. This thesis highlights the feasibility of UAS-based surveying at target scale (1–50 km2) and solidifies versatile survey approaches for multi-sensor integration. / Ziel dieser Arbeit war es, das Potenzial einer Drohnen-basierten Mineralexploration mit Multisensor-Datenintegration unter Verwendung optisch-spektroskopischer und magnetischer Methoden zu untersuchen, um u. a. übertragbare Arbeitsabläufe zu erstellen. Die untersuchte Literatur legt nahe, dass Drohnen-basierte Bildspektroskopie und magnetische Sensoren ein ausgereiftes technologisches Niveau erreichen und erhebliches Potenzial für die Anwendungsentwicklung bieten, aber es noch keine ausreichende Synergie von hyperspektralen und magnetischen Methoden gibt. Diese Arbeit umfasste drei Fallstudien, bei denen die Drohnengestützte Vermessung von geologischen Zielen in subarktischen bis arktischen Regionen angewendet wurde. Eine Kombination von Drohnen-Technologie mit RGB, Multi- und Hyperspektralkameras und Magnetometern ist vorteilhaft und schuf die Grundlage für eine integrierte Modellierung in den Fallstudien. Die Untersuchungen wurden in einem Gelände mit flacher und zerklüfteter Topografie, verdeckten Zielen und unter oft schlechten Lichtverhältnissen durchgeführt. Unter diesen Bedingungen war es das Ziel, die Anwendbarkeit von Drohnen-basierten Multisensordaten in verschiedenen Explorationsumgebungen zu bewerten. Hochauflösende Oberflächenbilder und Untergrundinformationen aus der Magnetik wurden fusioniert und gemeinsam interpretiert, dabei war eine selektive Gesteinsprobennahme und Analyse ein wesentlicher Bestandteil dieser Arbeit und für die Validierung notwendig. Für eine Eisenerzlagerstätte wurde eine einfache Ressourcenschätzung durchgeführt, indem Magnetik, bildspektroskopisch-basierte Indizes und 2D-Strukturinterpretation integriert wurden. Fotogrammetrische 3D-Modellierung, magnetisches forward-modelling und hyperspektrale Klassifizierungen wurden für eine Karbonatit-Intrusion angewendet, um einen kompletten Explorationsabschnitt zu erfassen. Eine Vektorinversion von magnetischen Daten von Disko Island, Grönland, wurden genutzt, um großräumige 3D-Modelle von undifferenzierten Erdrutschblöcken zu erstellen, sowie diese zu identifizieren und zu vermessen. Die integrierte spektrale und magnetische Kartierung in komplexen Gebieten verbesserte die Erkennungsrate und räumliche Auflösung von Erkundungszielen und reduzierte Zeit, Aufwand und benötigtes Probenmaterial für eine komplexe Interpretation. Der Prototyp einer Multispektralkamera, gebaut für eine Starrflügler-Drohne für die schnelle Vermessung, wurde entwickelt, erfolgreich getestet und zum Teil ausgewertet. Die vorgelegte Arbeit zeigt die Vorteile und Potenziale von Multisensor-Drohnen als praktisches, leichtes, sicheres, schnelles und komfortabel einsetzbares geowissenschaftliches Werkzeug, um digitale Modelle für präzise Rohstofferkundung und geologische Kartierung zu erstellen.