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Konferenzbeiträge

Anzahl der Treffer: 1996
Erstellt: Fri, 15 Jan 2021 23:03:55 +0100 in 0.0514 sec


Krey, Maximilian; Töpfer, Hannes;
Topology optimization of magnetoelectric sensors using Euler-Bernoulli beam theory. - In: Microactuators, Microsensors and Micromechanisms : MAMM 2020.. - Cham : Springer International Publishing, (2021), S. 115-124

A studied magnetic field sensor is based on resonant operation of magnetoelectric micro-electro-mechanical systems (MEMS). Subsequently to an applied magnetic field, the micro beam changes the eigenfrequency, due to the magnetostrictive effect. Euler-Bernoulli beam theory can calculate eigenfrequencies of bending vibrations of beams with high accuracy. Implementing more complex beam geometries is challenging, thus often the finite element method (FEM) is used. This paper deals with the modeling of prestressed beams with multilayered structure and discontinuities along the beam length using Euler-Bernoulli beam theory. The arising problems are addressed in detail. As an example, the model is applied to the studied magnetoelectric sensor and shows good accordance to FEM simulations. An optimization algorithm is used to find a sensor geometry that leads to high output signals utilizing the developed model as input for the minimization of a target function.



https://doi.org/10.1007/978-3-030-61652-6_10
Wagner, Christoph W.; Semper, Sebastian; Römer, Florian; Schönfeld, Anna; Del Galdo, Giovanni;
Hardware architecture for ultra-wideband channel impulse response measurements using compressed sensing. - In: 28th European Signal Processing Conference (EUSIPCO 2020) : proceedings : 24-28 August 2020, Amsterdam, The Nederlands.. - [Piscataway, NJ] : IEEE, (2021), S. 1663-1667

We propose a compact hardware architecture for measuring sparse channel impulse responses (IR) by extending the M-Sequence ultra-wideband (UWB) measurement principle with the concept of compressed sensing. A channel is excited with a periodic M-sequence and its response signal is observed using a Random Demodulator (RD), which observes pseudo-random linear combinations of the response signal at a rate significantly lower than the measurement bandwidth. The excitation signal and the RD mixing signal are generated from compactly implementable Linear Feedback Shift registers (LFSR) and operated from a common clock. A linear model is derived that allows retrieving an IR from a set of observations using Sparse-Signal-Recovery (SSR). A Matrix-free model implementation is possible due to the choice of synchronous LFSRs as signal generators, resulting in low computational complexity. For validation, real measurement data of a time-variant channel containing multipath components is processed by simulation models of our proposed architecture and the classic M-Sequence method. We show successful IR recovery using our architecture and SSR, outperforming the classic method significantly in terms of IR measurement rate. Compared to the classic method, the proposed architecture allows faster measurements of sparse time-varying channels, resulting in higher Doppler tolerance without increasing hardware or data stream complexity.



https://doi.org/10.23919/Eusipco47968.2020.9287454
Korobkov, Alexey A.; Diugurova, Marina K.; Haueisen, Jens; Haardt, Martin;
Multi-dimensional model order estimation using LineAr Regression of Global Eigenvalues (LaRGE) with applications to EEG and MEG recordings. - In: 28th European Signal Processing Conference (EUSIPCO 2020) : proceedings : 24-28 August 2020, Amsterdam, The Nederlands.. - [Piscataway, NJ] : IEEE, (2021), S. 1005-1009

The efficient estimation of an approximate model order is very important for real applications with multi-dimensional data if the observed low rank data is corrupted by additive noise. In this paper, we present a novel robust method for model order estimation of multi-dimensional data based on the LineAr Regression of Global Eigenvalues (LaRGE). The LaRGE method uses the multi-linear singular values obtained from the HOSVD of the measurement tensor to construct global eigenvalues. In contrast to the Modified Exponential Test (EFT) that also exploits the approximate exponential profile of the noise eigenvalues, LaRGE does not require the calculation of the probability of false alarm. Therefore, it is well suited for the analysis of biomedical data. The excellent performance of the LaRGE method is illustrated via simulations and results obtained from EEG as well as MEG recordings.



https://doi.org/10.23919/Eusipco47968.2020.9287523
Shala, Mendrit; Sewalkar, Parag; Seitz, Jochen;
On-demand quality-of-service for crucial vehicle-to-pedestrian communication. - In: IEEE Xplore digital library. - New York, NY : IEEE, ISSN 2473-2001, (2020), insges. 6 S.

https://doi.org/10.1109/WiMob50308.2020.9253416
Bauer, Julia; Andrich, Carsten; Ihlow, Alexander; Beuster, Niklas; Del Galdo, Giovanni;
Characterization of GPS disciplined oscillators using a laboratory GNSS simulation testbed. - In: IEEE IFCS-ISAF 2020 : Joint Conference of the IEEE International Frequency Control Symposium & IEEE International Symposium on Applications of Ferroelectrics : virtual conference, July 19-23, 2020 : 2020 symposium proceedings.. - Piscataway, NJ : IEEE, (2020), insges. 4 S.

This paper introduces a testbed to characterize the performance of GPS disciplined oscillators using a GNSS signal simulator and a measurement system based on software-defined radios and digital signal processing that allows to examine the stability of up to four devices with sub-nanosecond precision, time-coherently for 1 PPS and 10 MHz signals, in a controllable laboratory environment with reproducible and adjustable GNSS signal settings over a long-term observation period. To demonstrate the effectiveness of this method, four devices of one specific low-cost GPSDO type available to the authors are characterized and compared in terms of their positional accuracy and their time and frequency stability in steady state and during stabilization.



https://doi.org/10.1109/IFCS-ISAF41089.2020.9234932
Andrich, Carsten; Engelhardt, Maximilian; Ihlow, Alexander; Beuster, Niklas;
Measurement of drift and jitter of network synchronized distributed clocks. - In: IEEE IFCS-ISAF 2020 : Joint Conference of the IEEE International Frequency Control Symposium & IEEE International Symposium on Applications of Ferroelectrics : virtual conference, July 19-23, 2020 : 2020 symposium proceedings.. - Piscataway, NJ : IEEE, (2020), insges. 8 S.

We propose a measurement setup for simultaneous measurement of drift and jitter of network synchronized distributed clocks using only off-the-shelf components. A network interface card with hardware timestamping capability and a local GPS-synchronized PTP grandmaster combined with appropriate post-processing enable absolute time measurement with sub-microsecond accuracy. The setup is explained in detail and its use exemplified by a 34 day measurement campaign. By polling a selection of globally distributed, GPS-synchronized NTP servers, delay asymmetry measurements were enabled. A detailed analysis of results illustrates the time-variant statistical properties of the jitter.



https://doi.org/10.1109/IFCS-ISAF41089.2020.9234926
Andrich, Carsten; Engelhardt, Maximilian; Ihlow, Alexander; Beuster, Niklas; Del Galdo, Giovanni;
Stochastic modeling of short and long term clock skew. - In: IEEE IFCS-ISAF 2020 : Joint Conference of the IEEE International Frequency Control Symposium & IEEE International Symposium on Applications of Ferroelectrics : virtual conference, July 19-23, 2020 : 2020 symposium proceedings.. - Piscataway, NJ : IEEE, (2020), insges. 4 S.

Traditional black box clock skew models are either the power-law noise model or a more recent approach based on auto-regressive (AR) filters. Unfortunately, neither algorithm can accurately model short and long term skew due to limited degrees of freedom or stability constraints. We propose a novel model that employs the current AR algorithm recursively with appropriate pre- and post-processing to achieve numeric stability and accurate reproduction of short and long term effects. The model coefficients are derived from a measured skew signal, with the model output matching an exemplary original signal closely in terms of Allan variance and time-domain behavior.



https://doi.org/10.1109/IFCS-ISAF41089.2020.9234818
Bauer, Julia; Andrich, Carsten; Ihlow, Alexander; Beuster, Niklas; Del Galdo, Giovanni;
Characterizing GPS disciplined oscillators for distributed vehicle-to-X measurement applications. - In: IEEE IFCS-ISAF 2020 : Joint Conference of the IEEE International Frequency Control Symposium & IEEE International Symposium on Applications of Ferroelectrics : virtual conference, July 19-23, 2020 : 2020 symposium proceedings.. - Piscataway, NJ : IEEE, (2020), insges. 4 S.

In this paper, we analyze the reference signal stability of 1 PPS and 10 MHz signals provided by a low-cost GPS disciplined oscillator under application specific conditions using a comparable light-weight measurement system based on software defined radio and digital signal processing. In mobile measurement scenarios, GPS signal impairments are inevitable, due to obstacles such as buildings, street canyons, bridges, and tunnels. Therefore, we preliminarily characterize four GPSDOs under test in a stationary setup using controlled GPS reception loss to drive them into alternating operation modes, namely free-run, disciplined and holdover mode. Further, we conducted a more than 100 km real-world diversified test drive to characterize the performance of the particular GPSDO as realistically as possible for the intended use in mobile V2X measurements.



https://doi.org/10.1109/IFCS-ISAF41089.2020.9234915
Schmidt, Leander; Römer, Florian; Böttger, David; Leinenbach, Frank; Straß, Benjamin; Wolter, Bernd; Schricker, Klaus; Seibold, Marc; Bergmann, Jean Pierre; Del Galdo, Giovanni;
Acoustic process monitoring in laser beam welding. - In: Procedia CIRP. - Amsterdam [u.a.] : Elsevier, ISSN 2212-8271, Bd. 94 (2020), S. 763-768

Structure-borne acoustic emission (AE) measurement shows major advantages regarding quality assurance and process control in industrial applications. In this paper, laser beam welding of steel and aluminum was carried out under varying process parameters (welding speed, focal position) in order to provide data by means of structure-borne AE and simultaneously high-speed video recordings. The analysis is based on conventionally (e.g. filtering, autocorrelation, spectrograms) as well as machine learning methods (convolutional neural nets) and showed promising results with respect to the use of structure-borne AE for process monitoring using the example of spatter formation.



https://doi.org/10.1016/j.procir.2020.09.139
Kreismann, Jakob; Kim, Jaewon; Bosch, Martí; Hein, Matthias; Sinzinger, Stefan; Hentschel, Martina;
Super-directional light emission and emission reversal from micro cavity arrays. - In: DPG-Frühjahrstagung (DPG Spring Meeting) of the Condensed Matter Section (SKM) together with the DPG Division Environmental Physics and the Working Groups Accelerator Physics; Equal Opportunities; Energy; Industry and Business; Physics, Modern IT and Artificial Intelligence, Young DPG. - Bad Honnef : Deutsche Physikalische Gesellschaft, (2020), KFM 7.1