Regelstrategien für die Echtzeit-Leistungsregelung beim gepulsten Laserstrahlschweißen von Aluminium-Kupfer-Mischverbindungen. - In: Innovative Verfahren der Lasermaterialbearbeitung, (2021), S. 33-42
Six decades of research on 2D materials: progress, dead ends, and new horizons. - In: LAEDC 2021, (2021), insges. 4 S.
https://doi.org/10.1109/LAEDC51812.2021.9437918
CSI-based localization with CNNs exploiting phase information. - In: 2021 IEEE Wireless Communications and Networking Conference (WCNC), (2021), insges. 6 S.
In this paper we study the use of the Channel State Information (CSI) as fingerprint inputs of a Convolutional Neural Network (CNN) for localization. We examine whether the CSI can be used as a distinct fingerprint corresponding to a single position by considering the inconsistencies with its raw phase that cause the CSI to be unreliable. We propose two methods to produce reliable fingerprints including the phase information. Furthermore, we examine the structure of the CNN and more specifically the impact of pooling on the positioning performance, and show that pooling over the subcarriers can be more beneficial than over the antennas.
https://doi.org/10.1109/WCNC49053.2021.9417561
Parallel field segmentation concept in ER/MR dampers for a simpler control system. - In: Actuator 2021, (2021), S. 385-388
Electromagnetic actuators. - In: Actuator 2021, (2021), S. 24-29
DRIE Si nanowire arrays supported nano-carbon film for deriving high specific energy supercapacitors on-chip. - In: 30th Micromechanics and Microsystems Europe Workshop (MME) 2019, 18-20 August 2019, Wolfson College, Oxford, United Kingdom, (2021), 012005, S. 1-6
Supercapacitor is a promising solution to storage of pulsed energy generated by MEMS energy harvesting systems, relying on its faster charging/discharging capability than secondary battery. To improve the energy density of on-chip supercapacitor which shows potential for integration with MEMS devices, in this paper we first present a successful electrode design for high specific energy pseudo-supercapacitors on the basis of deep reactive ion etched Si nanowire array supported nano-carbon matrix. Widely used pseudo-capacitive manganese oxide active material is facilely deposited into the conductive nano-carbon matrix by a chemical bath deposition. The derived electrode exhibits a remarkable capacitance increase (around 4.5x enhancement) compared with the nano-carbon matrix benefiting from the contribution of pseudo-capacitive manganese oxide. Assembled sandwich prototype on-chip supercapacitors with a symmetric configuration offer a high specific capacitance of 741.6 mF cm^-2 when discharged at 1 mA cm^-2, and the energy density can attain as high as 51.5 [my]Wh cm^-2. The achieved high specific energy makes such on-chip supercapacitors attractive in the field of energy collection when cooperated with micro-or nano-energy generators.
https://doi.org/10.1088/1742-6596/1837/1/012005
Silicon interface passivation studied by modulated surface photovoltage spectroscopy. - In: Peruvian Workshop on Solar Energy 2020 (JOPES 2020), 25-26 June 2020, Lima, Peru, (2021), 012003, S. 1-7
We demonstrate that the modulated surface photovoltage spectroscopy (modulated SPS) technique can be applied to investigate interface states in the bandgap, i.e. interface passivation, of crystalline silicon coated with a downshift layer such as hydrogenated aluminum nitride with embedded terbium ions by suppressing straylight with a cut-off filter. Different hydrogen contents influence the surface photovoltage spectra at photon energies below the bandgap of crystalline silicon. Modulated SPS reveals that at higher hydrogen content there is a lower signal and, thus, a lower density of surface defect states. Our experiments show that modulated SPS can become a powerful tool for characterizing defect states at interfaces which cannot be easily studied by other methods.
https://doi.org/10.1088/1742-6596/1841/1/012003
Determination of instantaneous and maximal human exposure to 5G massive-MIMO base stations. - In: Focus on linking antennas and propagation with the automotive and 5G industries, (2021), insges. 5 S.
The roll-out of the 5G standard with novel functionalities brings with it the urgent need to evaluate the human exposure to massive-MIMO base stations. This paper discusses concepts for the measurement of instantaneous and maximal exposure in the sub-6 GHz frequency range (FR1). The concepts have been implemented with the NARDA SRM-3006 selective radiation meter. For instantaneous exposure, the Safety Evaluation mode with an averaging over multiple frequency sweeps has been identified appropriate. First results with provoked data traffic revealed exposures below 0.25 % of the ICNIRP 1998 power density reference levels. For maximal possible exposures, the exposure to the synchronization signal and physical broadcast channel block (SSB) should be measured in the Level Recorder mode and extrapolated to the signal bandwidth considering a measurement point-specific gain difference between traffic and broadcast beams. As another outcome of our studies, we argue that code-selective devices for SSB measurements are urgently needed.
https://doi.org/10.23919/EuCAP51087.2021.9411089
UHF RFID tag performance measurements for SLCs applications using DIY-positioners. - In: Focus on linking antennas and propagation with the automotive and 5G industries, (2021), insges. 5 S.
With this paper, we present cost-effective techniques to characterize UHF RFID performance with regards to small load carriers (SLC). A self-developed turntable-positioner is used to measure the antenna pattern of tags attached to empty SLCs, as well as SLCs filled with scrap metal. With the tag-positioner we presented in a recent publication, read range degradation of various tags near dissipative and conductive electro static discharge (ESD) protective material was investigated. We also measured the sensitivity of around 80 different tags in front of an SLC made of ESD protective material and compared their performance to operation in free-space propagation. To conduct the measurements themselves, we use commercial off-the-shelf readers like the R420 from Impinj, which we control via low level reader protocol (LLRP) commands, implemented in Python.
https://doi.org/10.23919/EuCAP51087.2021.9411100
On the modelling of the NLOS first multi-path component in stochastic spatial channel models. - In: Focus on linking antennas and propagation with the automotive and 5G industries, (2021), insges. 5 S.
Positioning and localization is one of the key features in the 5G and beyond wireless networks. Since accuracy strongly depends on the channel conditions, channel models are of special importance for the testing and development of such applications. While several localization methods are based on the time of arrival (ToA) and time-difference of arrival (TDoA), stochastic spatial channel models (SCMs) as the 3GPP don't consider absolute values on the delays of the non-line of sight (NLOS) multi-path components (MPCs), making these models not appropriate for these applications. Therefore, we investigate the time and angular characteristics of the first multi-path component (FMPC) using multi-band ray tracing (RT) simulations in order to extend stochastic SCMs to support localization applications in NLOS.
https://doi.org/10.23919/EuCAP51087.2021.9411142