Statische Korrekturen in der Seismik bei komplexen Topographien

Ein wichtiger Bestandteil jedes seismischen Datenprocessings ist die statische Korrektur. Sie dient zur Bereinigung von topographischen Unebenheiten, sowie Geschwindigkeitsstörungen die durch oberflächennahe Anomalien oder durch die Verwitterungsschicht hervorgerufen werden. Dabei wird die gesamte seismische Auslage nach unten gerechnet, um ein neues, tiefergelegenes Bezugsniveau zu erreichen. Die Zeitkorrektur an den seismischen Daten bewirkt dadurch einen Effekt, als hätten die aufgenommenen Signalen nie diese oberflächennahen Schichten durchlaufen. Um diese obersten 10er bzw. 100er Meter wegrechnen zu können, muss ein Geschwindigkeitsmodell vorhanden sein. Umso hochauflösender und genauer dieses bekannt ist, desto besser kann die Rechnung der Sources & Receivers auf die statische Bezugsebene erfolgen und dadurch die Störeffekte der seichten, meist unregelmäßigen Schichtung eliminiert werden. Bei dieser Diplomarbeit werden zwei verschiedene Methoden zur Erstellung eines solchen Geschwindigkeitsmodells getestet und mit einem bereits in der Produktion verwendeten Modell verglichen. Beim ersten Modell handelt es sich um eine 3D Tauchwellen-Tomographie, beim zweiten um eine 1D Inversion. Man versucht eine Möglichkeit zu finden, das Problem eines starken lateralen Geschwindigkeitskontrasts, welcher durch ein aufgefülltes Gletschertal geboten wird, zu bewältigen.An essential step in the processing of seismic data is the application of static corrections. They account for time shifts caused by topographic undulations, velocity anomalies in the near-surface and delayed travel times of the signal through the weathered layer. The entire seismic layout is treated as if the survey had taken place below the unconsolidated layers, by projecting sources and receivers vertically downwards onto a reference datum. The time shift applied to the seismic makes the traces appear as if they had never travelled through the weathered layer. In order to eliminate the effect of the shallow tens or hundreds of metres, a velocity model must be acquired. The quality and resolution of the model determines how accurately the sources and receivers can be projected down onto the statics datum and thus how well the delays and incoherent signals can be corrected. The presented thesis investigates two different methods employed in the calculation of such a velocity model and compares them to a previously computed model used in production seismic. One method deals with a 3D diving wave tomography, while the other looks at a 1D inversion of travel time curves. Both aim to solve the difficulties encountered in complex topographies, such as an overdeep glacial in-fill valley with strong lateral velocity contrasts

Zustandsüberwachung mit Regelfahrzeugen

Die Künstliche Intelligenz (KI) bzw. das maschinelle Lernen ermöglicht neue Ansätze für die Zustandsüberwachung der Bahninfrastruktur im laufenden Betrieb. Dieser Beitrag gibt einen Überblick über Forschungsarbeiten des Austrian Institute of Technology (AIT) und des Deutschen Zentrums für Luft- und Raumfahrt DLR e. V. zur Nutzung der Fahrzeug-Fahrweg-Interaktion zur Erkennung von Fehlzuständen an Schienen

Comparing On-board Vibration and Sound Measurements of Trams with Their Respective Pass-by-levels

In a first step towards mapping the sound and vibration immission produced by trams in Vienna, a trial was"br" conducted in 2016 which saw a tram in the city’s public transport network being equipped with an on-board"br" microphone near its unpowered bogie. The tram was previously equipped with four accelerometers on the wheel"br" bearings of the same bogie, one accelerometer on the bogie itself and another one on the chassis. On-board data is"br" collected with a sampling rate of 8192 Hz per accelerometer and 48 kHz for the microphone when the tram is in"br" motion. As the instrumented car covers all of Vienna’s tram network at regular intervals, the aim of the study was"br" to examine the correlation between the on-board records (emission) and the pass-by levels (immission) when the"br" tram travels at different velocities. The initial setup examined the correlation along a straight section of grooved"br" rail (gauge 1435 mm), while ongoing work aims to examine the correlation in curves and at junctions when driving"br" over switches

Mechanical Frequency Response Analysis of Lithium-Ion Batteries to Disclose Operational Parameters

During the charge and discharge process, lithium-ion batteries change their mechanical properties due to internal structural changes caused by intercalation and de-intercalation of the ions in the anode and cathode. Furthermore, the behavior changes over the lifetime of the battery due to several degradation mechanisms. The mechanical properties of the cell hold valuable information for monitoring these changes and additionally provide data for mechanical construction and further optimization of battery systems. Hence, in this manuscript, the mechanical frequency response function is investigated as a non-destructive method to determine parameters such as stiffness and damping of pouch cells and their correlation with the state of charge (SOC), the state of health (SOH), and the temperature of the cell. Using a mechanical shaker and an impedance head, it is shown that low amplitude forces of only a few Newton and a low frequency region of several hundred Hertz already suffice to show differences in the state of charge and state of health as well as in mechanical properties and the dependencies on temperature. Also the limitations of the method are shown, as the frequency response is not distinct for each parameter and thus, at the moment, does not allow absolute determination of a single value without prior system knowledge