Radar interferometry based settlement monitoring in tunnelling: visualisation and accuracy analyses

Background The accurate, efficient and economical monitoring of settlements caused by tunnel boring machines, especially in regions of particular interest such as critical inner city areas, has become an important aspect of the tunnelling operation. Besides conventional terrestrial based methods to capture settlements, satellite based techniques that can accurately determine displacements remotely, are increasingly being used to augment standard terrestrial measurements. However, not much attention has been paid to analyse the accuracy of satellite based measurement data. In addition, there is also a lack of studies on how to visualise the resulting huge amount of data in the context of both the tunnel advancement and the existing building infrastructure. Methods This paper introduces the basics of settlement monitoring using radar interferometry methods, in particular showing the results obtained by processing radar images from the TerraSAR-X satellite to monitor a downtown construction site in Düsseldorf, Germany, where a new underground line (“Wehrhahn-Linie”) is being built. By comparing terrestrial measurements with remote satellite based settlement data in temporal and spatial corridors, the accuracy of the radar interferometry method is shown. Moreover, a 4D visualisation concept is presented that correlates satellite and terrestrial based settlement data correlated with above-ground buildings and boring machine performance parameters within a Virtual Reality (VR) environment. Results By comparing up to 23,000 pairs of satellite and terrestrial based settlement data points of a real tunnelling project an accuracy of about ±1.5 mm in the measurement of deformation using the method of radar interferometry in urban areas can be stated. In addition, providing a visual analysis of data sources within a VR environment, the accuracy of terrestrial and satellite-based measurements can be visualised in different time steps. Sources of error that affect the degree of accuracy, such as atmospheric conditions, systematic errors in the evaluation of radar images and local events in the spatial corridor, can be quantified. In addition, the 4D visualisation can help reveal direct interdependencies between settlement data and boring machine performance data. Conclusions The Persistent Scatterer Interferometry (PSI) based on high resolution radar images of the TerraSAR-X satellite, in combination with conventional ground-based terrestrial measurements, provides a new settlement monitoring approach in tunnelling. For example, due to minimized surveying works and disruptions of construction activities on site and due to the large settlement area coming with a high magnitude of settlement data points, this combined monitoring approach is very practical and economical. Moreover, by visualizing the settlement data properly, the risk of damage of surface structures can be analysed and understood more precisely, which increases the safety of underground works

Standortkarte der Vegetation in Hessen 1:200 000 (potentielle natuerliche Vegetation der Waldflaeche und natuerliche Standorteignung fuer Acker- und Gruenland)

SIGLETIB Hannover: RO 1602(33)+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Bewegungskompensation für flugzeuggetragene SAR-Systeme

Das Buchkapitel "Bewegungskompensation für flugzeuggetragene SAR-Systeme" befasst sich mit Phasenfehlern deterministischer und statistischer Natur, der Erfassung von Bewegungsfehlern und deren Kompensation bei der SAR-Bildprozessierung. Ideale Flugbedingungen, also die Annahme, die Plattform bewege sich mit konstanter Geschwindigkeit entlang der idealen Trajektorie, können bei flugzeuggetragenen SAR-Systemen nicht implizit vorausgesetzt werden. Es müssen eine variable Vorwärtsgeschwindigkeit, eine variable Flughöhe, seitliche Abweichungen von der nominellen Flugbahn und ein unerwünschtes Schwenken der Radarantenne in Betracht gezogen werden. Folge dieser Abweichungen von der nominellen Position und Lage sind eine veränderte Phasenhistorie, Laufzeitschwankungen sowie eine Amplitudenmodulation des Rückstreusignals. Als Folge stellen sich im SAR-Bild geometrische Verzerrungen, eine Verringerung der räumlichen Auflösung in Azimutrichtung und eine Verminderung des Bildkontrastes ein. Bei der Kompensation dieser Bewegungsfehler wird die Position der Plattform bestimmt, in Korrekturparameter umgesetzt und bei der Bildprozessierung zur Fehlerkorrektur berücksichtigt

Characterization of Upper Extremity Kinematics Using Virtual Reality Movement Tasks and Wearable IMU Technology

Task-specific training has been shown to be an effective neuromotor rehabilitation intervention, however, this repetitive approach is not always very engaging. Virtual reality (VR) systems are becoming increasingly popular in therapy due to their ability to encourage movement through customizable and immersive environments. Additionally, VR can allow for a standardization of tasks that is often lacking in upper extremity research. Here, 16 healthy participants performed upper extremity movement tasks synced to music, using a commercially available VR game known as Beat Saber. VR tasks were customized to characterize participants\u27 joint angles with respect to each task\u27s specified cardinal direction (inward, outward, upward, or downward) and relative task location (medial, lateral, high, and/or low). Movement levels were designed using three common therapeutic approaches: (1) one arm moving only (unilateral), (2) two arms moving in mirrored directions about the participant\u27s midline (mirrored), or (3) two arms moving in opposing directions about the participant\u27s midline (opposing). Movement was quantified using an XSens System, a wearable inertial measurement unit (IMU) technology. Results reveal a highly engaging and effective approach to quantifying movement strategies. Inward and outward (horizontal) tasks resulted in decreased wrist extension. Upward and downward (vertical) tasks resulted in increased shoulder flexion, wrist radial deviation, wrist ulnar deviation, and elbow flexion. Lastly, compared to opposing, mirrored, and unilateral movement levels often exaggerated joint angles. Virtual reality games, like Beat Saber, offer a repeatable and customizable upper extremity intervention that has the potential to increase motivation in therapeutic applications

Spin-resolved photoelectron spectroscopy of HBr in the resonance region of electron autoionization

Salzmann M, Böwering N, Klausing H-W, Kuntze R, Heinzmann U. Spin-resolved photoelectron spectroscopy of HBr in the resonance region of electron autoionization. Journal of Physics B: Atomic, Molecular and Optical Physics. 1994;27(10):1981-1992