Buchbeiträge des InIT der TU IlmenauBuchbeiträge des InIT der TU Ilmenau
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Altinel, Berk; Asghar, Ehtisham; Berlt, Philipp; Buddappagari, Sreehari; Bornkessel, Christian; Singh, Jasmeet; Hein, Matthias
Practical aspects of automotive measurements and virtual-drive testing. - In: Modern automotive antenna measurements, (2022), S. 221-246

Römer, Florian; Kirchhof, Jan; Krieg, Fabian; Pérez, Eduardo
Compressed Sensing: from big data to relevant data. - In: Handbook of Nondestructive Evaluation 4.0, (2022), S. 329-352

Though the ever-increasing availability of digital data in the context of NDE 4.0 is mostly considered a blessing, it can turn to a curse quite rapidly: managing large amounts of data puts a burden on the sensor devices in terms of sampling and transmission, the networks, as well as the server infrastructure in terms of storing, maintaining, and accessing the data. Yet, NDE data can be highly redundant so the storage of massive amounts of data may indeed be wasteful. This is the main reason why focusing on relevant data as early as possible in the NDE process is highly advocated in the context of NDE 4.0. This chapter introduces Compressed Sensing as a potential approach to put this vision to practice. Compressed Sensing theory has shown that sampling signals with sampling rates that are significantly below the Shannon-Nyquist rate is possible without loss of information, provided that prior knowledge about the signals to be acquired is available. In fact, we may sample as low as the actual information rate if our prior knowledge is sufficiently accurate. In the NDE 4.0 context, prior knowledge can stem from the known inspection task and geometry but it can also include previous recordings of the same piece (such as in Structural Health Monitoring), information stored in the digital product memory along the products’ life cycle, or predictions generated through the products’ digital twins. In addition to data reduction, reconstruction algorithms developed in the Compressed Sensing community can be applied for enhanced processing of NDE data, providing added value in terms of accuracy or reliability. The chapter introduces Compressed Sensing basics and gives some concrete examples of its application in the NDE 4.0 context, in particular for ultrasound.



Ardah, Khaled; Haardt, Martin; Liu, Tianyi; Matter, Frederic; Pesavento, Marius; Pfetsch, Marc E.
Recovery under side constraints. - In: Compressed sensing in information processing, (2022), S. 213-246

This chapter addresses sparse signal reconstruction under various types of structural side constraints with applications in multi-antenna systems. Side constraints may result from prior information on the measurement system and the sparse signal structure. They may involve the structure of the sensing matrix, the structure of the non-zero support values, the temporal structure of the sparse representation vector, and the nonlinear measurement structure. First, we demonstrate how a priori information in the form of structural side constraints influence recovery guarantees (null space properties) using ℓ1-minimization. Furthermore, for constant modulus signals, signals with row, block, and rank sparsity, as well as non-circular signals, we illustrate how structural prior information can be used to devise efficient algorithms with improved recovery performance and reduced computational complexity. Finally, we address the measurement system design for linear and nonlinear measurements of sparse signals. To this end, we derive a new linear mixing matrix design based on coherence minimization. Then, we extend our focus to nonlinear measurement systems where we design parallel optimization algorithms to efficiently compute stationary points in the sparse phase-retrieval problem with and without dictionary learning.



Müller, Robert; Dupleich, Diego
THz broadband channel sounders. - In: THz Communications, (2022), S. 37-48

This chapter is the perfect introduction to get an overview of THz channel sounder technologies. Additionally, all relevant state of the art and references for the field of THz channel sounding are summarized. The aim of the THz sounder chapter is to create a basic understanding of measurement setups and challenges for the measurement of the electromagnetic wave propagation in the THz range. All necessary principles, from generating the transmit signal over different mixing principles to the THz band and the data acquisition, are compact summarized.



Brauer, Hartmut; Ziolkowski, Marek
Motion-induced eddy current testing. - In: Handbook of advanced nondestructive evaluation, (2019), S. 781-825

Nondestructive material testing and evaluation is a vast interdisciplinary field as well as a challenge due to the variety of applications. Whereas the focus of nondestructive testing is to identify anomalies within a specimen, the reconstruction of defect properties and their influence on the materials usability is the focus of nondestructive evaluation. In this chapter the technology of motion-induced eddy current testing (MIECT) is introduced. In contrast to traditional eddy current testing (ECT) methods, MIECT makes use of relative motion between the object under test and permanent magnets. The induced eddy currents interact with the applied magnetic field and result in a Lorentz force, depending on the impressed magnetic induction, the electrical conductivity, and the measuring velocity. Because permanent magnets produce considerably stronger magnetic fields than current-carrying ECT coils, even deep internal defects can be detected using the Lorentz force eddy current testing (LET). It is shown how the electromagnetic fields can be described theoretically and simulated numerically, as well as how imperfections/defects in non-ferromagnetic, conducting specimens can be detected using an appropriate laboratory environment. Comparative studies have shown that LET applied to metallic composite material or friction stir welds is a promising and competitive alternative to traditional ECT methods enabling the contactless evaluation of moving electrical conductors.



https://doi.org/10.1007/978-3-319-26553-7_25
Uhlig, Robert P.; Brauer, Hartmut; Weise, Konstantin; Ziolkowski, Marek
Applications. - In: Motion-induced eddy current techniques for non-destructive testing and evaluation, ISBN 978-1-78561-215-2, (2018), S. 243-305

Brauer, Hartmut;
Lorentz force evaluation. - In: Motion-induced eddy current techniques for non-destructive testing and evaluation, ISBN 978-1-78561-215-2, (2018), S. 227-242

Carlstedt, Matthias; Weise, Konstantin
Experiments and LET measurements. - In: Motion-induced eddy current techniques for non-destructive testing and evaluation, ISBN 978-1-78561-215-2, (2018), S. 175-225

Carlstedt, Matthias; Brauer, Hartmut; Weise, Konstantin
Sensors for MIECT. - In: Motion-induced eddy current techniques for non-destructive testing and evaluation, ISBN 978-1-78561-215-2, (2018), S. 137-174

Ziolkowski, Marek; Zec, Mladen; Weise, Konstantin
Forward simulation methods. - In: Motion-induced eddy current techniques for non-destructive testing and evaluation, ISBN 978-1-78561-215-2, (2018), S. 47-136