Gravity gradient tensor (GGT) data contains the second derivatives of the Earth’s gravitational potential in three orthogonal directions. GGT data can be measured either using land, airborne, marine or space platforms. In the last two decades, the applications of GGT data in hydrocarbon exploration, mineral exploration and structural geology have increased considerably. This work focuses on developing new interpretation techniques for GGT data as well as pseudo-gravity gradient tensor (PGGT) derived from measured magnetic field. The applications of developed methods are demonstrated on a GGT data set from the Vredefort impact structure, South Africa and a magnetic data set from the Särna area, west central Sweden. The eigenvectors of the symmetric GGT can be used to estimate the position of the causative body as well as its strike direction. For a given measurement point, the eigenvector corresponding to the maximum eigenvalue points approximately toward the center of mass of the source body. For quasi 2D structures, the strike direction of the source can be estimated from the direction of the eigenvectors corresponding to the smallest eigenvalues. The same properties of GGT are valid for the pseudo-gravity gradient tensor (PGGT) derived from magnetic field data assuming that the magnetization direction is known. The analytic signal concept is applied to GGT data in three dimensions. Three analytic signal functions are introduced along x-, y- and z-directions which are called directional analytic signals. The directional analytic signals are homogenous and satisfy Euler’s homogeneity equation. Euler deconvolution of directional analytic signals can be used to locate causative bodies. The structural index of the gravity field is automatically identified from solving three Euler equations derived from the GGT for a set of data points located within a square window with adjustable size. For 2D causative bodies with geometry striking in the y-direction, the measured gxz and gzz components of GGT can be jointly inverted for estimating the parameters of infinite dike and geological contact models. Once the strike direction of 2D causative body is estimated, the measured components can be transformed into the strike coordinate system. The GGT data within a set of square windows for both infinite dike and geological contact models are deconvolved and the best model is chosen based on the smallest data fit error. / Felaktigt tryckt som Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 730

L’objectif de cette thèse est deconcevoir et de réaliser un moteurpiézoélectrique destiné à une application derécupération de chaleur du gaz d’échappement.Cette application nécessite un couplerelativement élevé, une compacité importante,une endurance thermique et un coût acceptable.Afin d’atteindre ce but, la conception du moteurpasse par le choix de son mode defonctionnement. Ce choix est fait en se basantsur des critères comme bas coût, fort couple etcompacité importante.Après la détermination de l’architecture dumoteur piézoélectrique, la modélisation estabordée. Le but du modèle est de calculer lescaractéristiques couple/vitesse connaissantses dimensions et ses matériaux, l’état desurface du contact, la précontrainte et la tensiond’alimentation.La modélisation développée était validée pardes mesures expérimentales.Dans la dernière partie, le moteur dimensionnéest réalisé et testé. Son comportementdynamique et ces caractéristiquescouple/vitesse étaient mesurés. A l’exceptiondu couple à l’arrêt et celui de blocage, toutes lesperformances requises par l’application étaientremplies.Finalement, les résultats de modèle sontcomparés aux mesures faites sur le prototype.Le comportement dynamique était bienreproduit par la modélisation. Néanmoins, uneimprécision du calcul des déplacements dustator était constatée. Cela implique uneimprécision du calcul des caractéristiquesmoteur. Il s’avère que cette imprécision est liéeà l’absence du coefficient d’amortissement decontact. / The goal of this thesis is to designand build a piezoelectric motor for an exhaustgas heat recovery application. This applicationrequires relatively high torque, highcompactness, thermal endurance and acceptablecost.In order to achieve this goal, the design of theengine passes by the choice of its mode ofoperation. This choice is made based on criteriasuch as low cost, high torque and compactness.After the determination of the architecture ofthe piezoelectric motor, the modelling isaddressed. The purpose of the model is tocompute the torque/speed characteristicsknowing the motor dimensions and materials,the surface state of the contact, the precompressionforce and the supply voltage.The modeling developed was validated byexperimental measurements.In the last part, the motor is build and tested. Itsdynamic behavior and torque/speedcharacteristics were measured. With theexception of the peak and blocking torque, allthe performances required by the applicationwere fulfilled.Finally, the model results are compared to themeasurements done on the prototype. Thedynamic behavior is well predicted by themodel. However, the model is not able tocompute accurately the stator displacements.This implies inaccuracy in the motorcharacteristics computation. It turns out thatthey are related to the absence of the coefficientof contact damping.

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Der Vortrag beschreibt, wie mittels des Kontaktmodells mit endlicher Reibung in Creo Simulate 3.0 ein Schwungrad mit axial verschraubtem mit Kegel-Presssitz berechnet werden kann. Da in Creo Simulate 3.0 des Softwareentwicklers PTC das Kontaktmodell mit endlicher Reibung nur für die Theorie großer Verformungen implementiert ist, nicht jedoch für einfache Analysen mit kleinen Deformationen, muss der Anwender einige softwareseitige Einschränkungen geschickt umgehen. Es werden Vorgehensweisen vorgeschlagen, wie der Anwender dies bewerkstelligen kann. Ein besonderer Schwerpunkt liegt dabei auf der Modellierung von Schrauben sowie der Einstellung der Schraubenvorspannung. Rechenergebnisse des Programms werden mit analytischen Lösungen verglichen. / The presentation describes how to analyze a flywheel with axially bolted hub-shaft- connection using a conical press fit with help of the finite friction contact model in Creo Simulate 3.0. Since Creo Simulate 3.0 from PTC offers a finite friction contact model implementation just for large displacement analysis, but not for simple analyses with small displacements, the user has to work around a couple of code specific limitations. Best practices are proposed how to do this. Special attention is paid on bolt modeling and preload adjustment. Analysis results are compared with analytical solutions.