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  • Publication
    Automated Cone and Vessel Analysis in Adaptive Optics Like Retinal Images for Clinical Diagnostics Support
    ( 2023)
    Hertlein, Anna-Sophia
    ;
    Wesarg, Stefan
    ;
    Jessica Schmidt
    ;
    Boche, Benjamin
    ;
    Pfeiffer, Norbert
    ;
    Matlach, Juliane
    Today, modern non-invasive Adaptive Optics (AO) imaging enables visualization of cone photoreceptors and vessels on a cellular level. High Magnification Module (HMM) images strongly resemble AO images and can be acquired fast and cost-effectly in clinical routine. Manual examination of those images, however, is tedious and time-consuming. Therefore, methods are needed to automatically analyse HMM images to facilitate the work of ophthalmologists. In this work an automatic cone detection method is presented that robustly detects cones in these images of both healthy and glaucoma patients. In addition, a vessel segmentation algorithm is provided to mask vessels during cone detection and additionally provide the ophthalmologist with vessel diameters that aid in monitoring ocular and cardiovascular diseases. The results on the given data are comparable to the performance of a trained expert and the methods are already being used in clinical practice.
  • Publication
    An Echo Suppression Delay Estimator for Angle-of-Arrival Ultrasonic Indoor Localization
    ( 2021)
    Gabrielli, Andrea
    ;
    Xiong, Wenxin
    ;
    Schott, Jan Dominik
    ;
    Fischer, Georg
    ;
    Wendeberg, Johannes
    ;
    Höflinger, Fabian
    ;
    Reindl, Leonhard M.
    ;
    Schindelhauer, Christian
    ;
    Rupitsch, Stefan J.
    In this article, we propose a new robust, stable, accurate, and efficient time-delay estimation scheme for the angle-of-arrival (AoA) ultrasonic indoor single-source localization systems. The AoA technique employing microphone arrays and ultrasonic signal emitting sources has turned out to be a promising alternative to the conventional distance-based ultrawideband systems for indoor localization. The crux of AoA estimation lies in the derivation of time-delay estimates, which is typically handled by advanced digital signal processing approaches based on cross-correlation and matching algorithms. The calculation of the channel response for each received signal and the conversion from the time to the time-delay domain consent our echo suppression delay estimator (ESDE) to apply echo suppression, in order to overcome the typical challenges introduced by the channel in indoor environments. Moreover, the optimization of the cross-correlation algorithm through oversampling the cross power spectrum and the curve-fitting algorithm allows to ensure subsample precision results. The performances of our developed AoA estimation system are evaluated by carrying out real-world experiments and compared with the state-of-the-art generalized cross correlators. Our ESDE algorithm is shown to outperform several generalized solutions.
  • Publication
    Blockchain and AI - Cyber-Physical Production Systems
    ( 2019)
    Sprenger, Philipp
    ;
    Sparer, Robert
    A new joint project between Fraunhofer IML and TU Dortmund University combines blockchain, IoT and artificial intelligence (AI). The demonstrator for ""cyber-physical production systems (CPPS)"" integrates smart contracts and blockchain technology into a multi-agent system at shop-floor level. The system covers negotiations, financial transactions and agile self-organisation while employing only limited hardware resources in a near real-time environment.
  • Publication
    Prediction of subgap states in Zn- and Sn-based oxides using various exchange-correlation functionals
    ( 2014)
    Körner, W.
    ;
    Urban, D.F.
    ;
    Ramo, D.M.
    ;
    Bristowe, P.D.
    ;
    Elsässer, C.
    We present a density-functional-theory analysis of crystalline and amorphous Zn- and Sn-based oxide systems which focuses on the electronic defect states within the band gap. A comparison of these electronic levels reveals that the hybrid functionals PBE0, HSE06, or B3LYP agree with a self-interaction corrected (SIC) local-density-approximation functional on occupied defect levels when similar treatments of the self-interaction are considered. However, for unoccupied levels, the hybrid functionals and the SIC approach lead to very different predictions. We show that a prerequisite for the determination of the energetic position of subgap states in these oxides is that a functional needs to predict correctly the electronic band structure over a wide energy range and not just close to the band gap. We conclude that for accurate defect levels, an adequate treatment of the self-interaction problem is required especially in the presence of nearby metal-metal interactions.