Current publications of the Faculty of Engineering

2021

 back to the year overview

• Hanemann T, Antusch S, Baumgaertner S, Bonk S, Klein A, Walter H, Wilhelm D
  3D-gedruckte PEEK Formeinsätze für das Mikropulverspritzgießen
  2021 MikroSystemTechnik Kongress 2021 VDE Verlag GmbH, pages: 60 - 63
  » show abstract« hide abstract
  Abstract

  Mittels Fused Filament Fabrication (FFF) 3D-gedruckte Kunststoff-Formwerkzeuge stellen eine kostengünstige Möglichkeit dar, im Sinne eines Rapid Tooling schnell und kostengünstig die Abformung von Kunststoffbauteilen zu erlauben. Aufgrund der schlechten Wärmeleitfähigkeit von Polymeren muss der als Formeinsatz zu verwendende Kunststoff eine hohe Dauergebrauchstemperatur aufweisen, um eine gute Abformqualität zu ermöglichen. Diese Arbeit beschreibt die Prozessentwicklung der Formeinsatzherstellung mittels FFF aus Polyetheretherketon (PEEK) und dessen Abformung im keramischen Pulverspritzguss. Es konnten erste keramische Grünlinge in guter Bauteilqualität abgeformt werden.
• Bast H, Brosi P, Kalmbach J, Lehmann A
  An Efficient RDF Converter and SPARQL Endpoint for the Complete OpenStreetMap Data
  2021 SIGSPATIAL
  » show abstract« hide abstract
  Abstract

  We present osm2rdf, a tool for converting OpenStreetMap (OSM) data to RDF triples, along with an efficient SPARQL endpoint and a convenient user interface for formulating SPARQL queries on that data. Unlike previous tools, osm2rdf retains all data provided by OSM, including the complete object geometries. Optionally, the tool can output explicit triples realizing the spatial relations contains and intersects. We provide weekly updates of the data (for the whole planet and also per continent and per country) on https://osm2rdf.cs.uni-freiburg.de. The tool is publicly available on GitHub. The SPARQL endpoint is realized via the open-source SPARQL engine QLever. We extended QLever to enable the efficient geometric filtering of a result by a given axis-parallel rectangle. The QLever UI provides interactive context-sensitive autocompletion that helps constructing SPARQL queries without prior knowledge of the details of the data.
  
  
   
  Download file
• Bast H, Hertel M, Mostafa M. Mohamed
  Tokenization Repair in the Presence of Spelling Errors
  2021 CoNLL
  » show abstract« hide abstract
  Abstract

  We consider the following tokenization repair problem: Given a natural language text with any combination of missing or spurious spaces, correct these. Spelling errors can be present, but it’s not part of the problem to correct them. For example, given: “Tispa per isabout token izaionrep air”, compute “Tis paper is about tokenizaion repair”. We identify three key ingredients of highquality tokenization repair, all missing from previous work: deep language models with a bidirectional component, training the models on text with spelling errors, and making use of the space information already present. Our methods also improve existing spell checkers by fixing not only more tokenization errors but also more spelling errors: once it is clear which characters form a word, it is much easier for them to figure out the correct word. We provide six benchmarks that cover three use cases (OCR errors, text extraction from PDF, human errors) and the cases of partially correct space information and all spaces missing. We evaluate our methods against the best existing methods and a non-trivial baseline. We provide full reproducibility under https://ad.cs.uni-freiburg.de/publications .
  
  
   
  Download file
• Hallak A, Wilde J
  Optimization of the Curing Process of dual-hardening Adhesive used in Thermoplastic Injection Molded Housings
  2021 EURADH - 13th European Adhesion Conference, Antibes, France
• Qazzazie-Hauser A, Honnef K, Hanemann T
  Additive Fertigung von Polysilazan als präkeramisches Polymer für die Herstellung von passivierenden Dünnschichtkontakten für Solarzellen
  2021 MikroSystemTechnik Kongress 2021, Stuttgart-Ludwigsburg, FRG VDE Verlag GmbH, Berlin, ISBN 978-3-8007-5656-8, pages: 376 - 379
  » show abstract« hide abstract
  Abstract

  Im Rahmen dieser Arbeit wurde eine Tinte für die additive Fertigung, speziell das Tintenstrahldrucken, entwickelt, welche als passivierender Dünnschichtkontakt in Silizium-Solarzellen eingesetzt werden soll. Die Tinte (AQ01), die hauptsäch-lich aus dem präkeramischen Polymer Polyorganosilazan besteht, wurde hinsichtlich ihrer rheologischen, strukturellen und thermischen Eigenschaften untersucht. Anschließend wurde die Druckbarkeit von Dünnschichten mittels Tintenstrahldruckers geprüft. Die Ergebnisse zeigen, dass die entwickelte Tinte die Anforderungen des Tintenstrahldruckers erfüllt, da sie sowohl eine niedrige Viskosität (unter 20 mPa∙s) als auch Newton‘sches Verhalten bei hohen Scherraten aufweist. Zusätzlich hat die Tinte eine Oberflächenspannung von 21 mN/m2. Die entwickelte Tinte konnte photochemisch vernetzt werden und anschließend bei hohen Temperaturen (950 °C) in eine amorphe Keramik überführt werden. Anhand der FTIR-Spektren konnte die chemische Struktur der Tinte sowohl nach der Polymerisation als auch nach der Pyrolyse untersucht werden. Die Ergebnisse zeigen, dass die Vernetzung überwiegend über radikalische Polymerisation der Vi-nylgruppe abgelaufen ist. Darüber hinaus handelt es sich bei der resultierenden Keramik um Siliziumcarbonitrid (SiCN). Die keramische Ausbeute liegt bei ungefähr 76 %.
• Pfeifer C, Vieten T, Jung J, Gläser K, Hanemann T
  Additive Fertigung, Laserdirektstrukturierung und chemische Metallisierung von Duroplasten: Material- und Prozessentwicklung
  2021 MikroSystemTechnik Kongress 2021, Stuttgart-Ludwigsburg, FRG VDE Verlag GmbH, Berlin, ISBN 978-3-8007-5656-8, pages: 372 - 375
  » show abstract« hide abstract
  Abstract

  Die Produktion von Komponenten mittels additiver Fertigung erlangt im Rahmen der zunehmenden Individualisierung von Produkten immer größere Bedeutung. Im Gegensatz zu konventionellen Herstellungsprozessen ist die additive Fertigung als werkzeugloses Verfahren auch bei kleinen Stückzahlen bis hin zur Losgröße eins wirtschaftlich, da der Initialaufwand sehr gering und die Designflexibilität sehr hoch ist. In diesem Projekt soll für die additive Fertigung mittels Stereolithographie ein laseraktivierbares Material entwickelt und Verfahren zum Aufbau, zur Laseraktivierung und selektiven Metallisierung additiv gefertigter 3D-Kunststoffbauteile untersucht werden. Die Kombination von additiver Fertigung des 3D-Kunststoffbauteils und laserbasierter Strukturierung ermöglicht eine komplett werkzeuglose Fertigung mit auf der Oberfläche aufgebrachten Leiterbahnstrukturen für kunststoffbasierte mechatronische oder mikrosystemtechnische Baugruppen. Besonderes Augenmerk liegt hierbei auch auf der Herstellung von Polymer-Keramik-Kompositen mit hoher Wärmeleitfähigkeit ≥ 1 W/(mK). Diese garantiert den raschen Abtransport der Abwärme von elektrischen Bauteilen und ermöglicht im Verbund mit der hohen mechanischen und chemischen Stabilität von Duroplasten den Einsatz in technisch anspruchsvollen Umgebungen.
• Ketterer I, Yang C K, Frey M, Wappler M, Hanemann T
  Bleifreie Bariumtitanat-Piezokeramik dargestellt durch elektrophoretische Abscheidung auf Graphitelektroden
  2021 MikroSystemTechnik Kongress 2021, Stuttgart-Ludwigsburg, FRG VDE Verlag GmbH, Berlin, ISBN 978-3-8007-5656-8, pages: 388 - 391
  » show abstract« hide abstract
  Abstract

  Die Toxizität von Blei macht die Suche nach bleifreien piezoelektrischen Keramiken und deren Optimierung zu einem aktuellen Forschungsthema. Diese Arbeit beschäftigt sich mit der Herstellung dünner, bleifreier Bariumtitanat-Keramiken mit einer Schichtdicke im Bereich von 50-150 μm ohne ein darunterliegendes Trägermaterial zur Anwendung in Aktoren. Die Keramikschichten wurden durch elektrophoretische Abscheidung auf Graphitelektroden dargestellt und anschließend einem Temperaturprogramm unterworfen, das aus drei Stufen besteht: 1. Entbindern bei 250-450 °C. 2. Veraschen der Graphitelektrode bei 700 °C. 3. Sintern der Piezokeramik bei Temperaturen ab 800 °C. Die Bariumtitanat-Keramiken wurden mittels Weißlichtinterferometrie, thermogravimetrischer Analyse und Rasterelektronenmikroskopie untersucht.
• Zürn M, Medesi A, Klein A, Schüßler C, Türk M, Dietrich S, Hanemann T
  Keramische Mikroreaktoren für die kontinuierliche hydrothermale Synthese (CHTS)
  2021 MikroSystemTechnik Kongress 2021, Stuttgart-Ludwigsburg, FRG VDE Verlag GmbH, Berlin, ISBN 978-3-8007-5656-8, pages: 586 - 589
  » show abstract« hide abstract
  Abstract

  Der Pulverspritzguss bietet als Massenfertigungsverfahren ein attraktives Herstellungsverfahren für die Serienfertigung von strukturierten Reaktorsystemen, die in der chemischen Industrie zunehmend an Bedeutung gewinnen, da diese eine hohe Produktqualität sowie Reaktionskontrolle durch eine integrierte in-situ-Sensorik bieten. Im vorliegenden Beitrag wird daher der Focus auf die Herstellung und besonders auf das Fügen von Aluminiumoxid-Reaktoren gelegt, welche mittels Spritzgießen hergestellt werden. Dabei hat sich gezeigt, dass eine hohe Produktqualität durch Optimierung der Nachbehandlungsschritte erzielt werden kann.
• Graf D, Jung J, Hanemann T
  Thermisch leitfähige Polymer-Keramik-Komposite für den Tintenstrahldruck
  2021 MikroSystemTechnik Kongress 2021, Stuttgart-Ludwigsburg, FRG VDE Verlag GmbH, Berlin, ISBN 978-3-8007-5656-8, pages: 384 - 387
  » show abstract« hide abstract
  Abstract

  Der Tintenstrahldruck ermöglicht das simultane und kontaktlose Abscheiden von mehreren Materialien, was die Herstellung neuer innovativer elektronischer Geräte bei starker Reduktion der Fertigungsschritte ermöglichen könnte. Druckbare elektrisch isolierende Polymer-Keramik-Komposite zur Betriebswärmeabführung könnten hierbei notwendig werden. Darum wurden in dieser Arbeit mit 3-(Trimethoxysilyl)propylmethacrylat (MPS) beschichtete Al2O3 Submikropartikel in einer Lösung aus dem Oligomethacrylat Genomer 4247 und dem flüchtigen Lösungsmittel Propylenglykolmonome-thyletheracetat (PGMMEA) zu einer keramischen Tinte dispergiert. Diese wurde mittels statischer Lichtstreuung, Transmissionselektronenmikroskopie (TEM), thermogravimetrischer Analyse, rheologischer Messung und Oberflächenspan-nungsmessung charakterisiert. Zudem wurden Tintenstrahldrucktests und eine Analyse der thermischen Leitfähigkeit des gedruckten Materials durchgeführt. Das Ergebnis der Untersuchung ist ein Material, das den Tintenstrahldruck von Kompositen mit einem Keramikgehalt von 50 Vol% und einer thermischen Leitfähigkeit von 1,2 W/(m·K) ermöglicht.
• Bast H, Brosi P, Storandt S
  Metro Maps on Flexible Base Grids
  2021 17th International Symposium on Spatial and Temporal Databases (SSTD '21)
  » show abstract« hide abstract
  Abstract

  We present new generic methods to efficiently draw schematized metro maps for a wide variety of layouts, including octilinear, hexalinear, and orthoradial maps. The maps are drawn by mapping the input graph to a suitable grid graph. Previous work was restricted to regular octilinear grids. In this work, we investigate a variety of grids, including triangular grids and orthoradial grids. In particular, we also construct sparse grids where the local node density adapts to the input graph (e.g. octilinear Hanan grids, which we introduce in this work). For octilinear maps, this reduces the grid size by a factor of up to 5 compared to previous work, while still achieving close-to-optimal layouts. For many maps, this reduction also leads to up to 5 times faster solution times of the underlying optimization problem. We evaluate our approach on five maps. All octilinear maps can be computed in under 0.5 seconds, all hexalinear and orthoradial maps can be computed in under 2.5 seconds.
  
  
   
  Download file
• Hallak A, Wilde J
  Assessment of High-Temperature Reliability of Adhesion Promoter for Self-Healing Mechanisms in Thermoplastic, Media-Tight Injection Molded Housings
  2021 in-adhesives, Symposium on Innovations in Adhesives and their Applications
• Kempiak C, Schiffmacher A, Chupryn A, Lindemann A, Wilde J, Rudzki J, Osterwald F
  Accelerated Qualification of Highly Reliable Chip Interconnect Technology by Power Cycling Under Thermal Overload
  2021 PCIM Europe digital days 2021
• Schiffmacher A, Strahringer D, Malasani S, Wilde J, Kempiak C, Lindemann A
  In Situ Degradation Monitoring Methods during Lifetime Testing of Power Electronic Module
  2021 2021 IEEE 71st Electronics Components and Technology Conference (ECTC)
• Rathmann, Lars, Geissler, Joschka, Reiterer, Alexander
  Concept for a novel airborne LiDAR system combining high-resolution snow height mapping with coregistered spatial information on the water content of the snowpack
  2021 SPIE Optical Metrology, 2021 , volume: 11785, 1178513
  » show abstract« hide abstract
  Abstract

  The impact of climate change on snow cover evolution is evident. Increasing amounts of winter precipitation as well as rising temperatures are causing the winter snow cover to change more and more rapidly within one season. To quantify the direct effects on hydrological cycles, spatially and temporally high-resolution information on snow height and the amount of water stored as snow (Snow Water Equivalent, SWE) is required on watershed scales. This paper presents the concept for a novel airborne light detection and ranging (LiDAR) system combining high-resolution snow height mapping with co-registered spatial information on the water content of the snowpack. Based on the optical characteristics of snow, we outline a detailed plan for dual-wavelength LiDAR sensor working at wavelengths of 1030 nm and 515 nm. By comparing the intensities received in the two channels, snow cover parameters like the effective grain size can be inferred. By means of recent snow hydrological models, from these data and the topographic snow depth maps then high resolution SWE maps can be deduced. We supplement our outline with conceptual LiDAR snow depth and reflectance measurements using a commercially available system, pointing out the impact of view angle dependence of received intensity and general applicability for future airborne LiDAR surveys.
• Stemmler, Simon
  Development of a high-speed, high-resolution multispectral camera system for airborne applications
  2021 , volume: 11785 1178512-1
  » show abstract« hide abstract
  Abstract

  For decades, satellite and aerial imagery have been the central element of mapping the earth's surface. The need for fast and frequent imaging, especially of smaller areas with unmanned aerial vehicles (UAVs) is gaining importance in various industries. Regular monitoring of agricultural areas, forests, coastal regions and urban areas are of utmost interest. Using UAVs to examine the worlds surface allows high resolution imagery captured in short time intervals without high costs as with the use of airplanes. This time series monitoring allows a quick detection of changes in the study area. The Fraunhofer-Institute for Physical Measurement Techniques IPM presents a compact and lightweight multispectral camera system. A 12 MP RGB-sensor and two 5.5 MP grayscale sensors are simultaneously capturing images. High frame rates, ultra-lightweight design, and the ability to easily adjust the aperture angle and wavelengths to be recorded open up many new applications. This ensures the use on a wide range of UAVs. Even with fast flying fixed wing UAVs, images can be acquired with high overlap. Further, we present results of a first measurement campaign.
• Merkle, Dominik, Reiterer, Alexander
  Evaluation of thermography-based automated delamination and cavity detection in concrete bridges
  2021 SPIE Optical Metrology, 2021
  » show abstract« hide abstract
  Abstract

  The stability, durability, and safety of concrete bridges are not only endangered by visible damages on the surface such as cracks or spalling, but also internal damages such as cavities, delamination, or material changes due to carbonation or moisture penetration. In Germany, the inspection is regulated by the norm DIN 1076. Accordingly, the inspectors with an experienced hearing still interpret the sound of a hammer on the entire underside of the bridge. Therefore, to inspect the underside of a bridge with its underlying infrastructures like traffic, water, or railroads and its usually complex and difficult to reach structures, including girders, a fast and reliable remote sensing approach is required to increase both efficiency and level of automation. This paper summarizes recent work using both passive and active thermography for bridge inspection. We compare three different sensor systems including the Parrot Anafi Thermal, the FLIR Vue Pro R, and the FLIR SC640 which could be used in a UAV, UGV, or human based inspection. To test and verify our concepts, we apply passive thermography on real concrete bridges in Freiburg (Germany) and derive 2D and 3D data using a photogrammetric approach. We analyse spatial and thermal resolution dependent on camera selection, working distance, weather conditions, and the bridges’ surface properties. For damage detection, we use high-pass or low-pass filtering dependent on the ambient temperature gradient. Moreover, we discuss further damage detection methods that could be integrated into the proposed processing workflow.
• Olshausen, Philipp, Roetner, Moritz, Koch, Christian, Reiterer, Alexander
  Multimodal measurement system for road analysis and surveying of road surroundings
  2021 SPIE Optical Metrology, 2021 Jürgen Beyerer, Michael Heizmann, volume: 11787 1178709-1
  » show abstract« hide abstract
  Abstract

  Identification and documentation of the state of road infrastructure are rapidly gaining in importance due to increased traffic. This requires regular inspection in order to optimize maintenance efforts. Additionally, construction projects are getting more complex and demand digital planning and building processes. The data, which forms the basis for these processes, must be rapidly acquired and it must be digital. In this paper, a measurement vehicle is presented that efficiently collects all desired data. The vehicle is based on a modular system platform from the Fraunhofer-Institute for Physical Measurement Techniques IPM. It enables measurements for road analysis while driving with up to 80 km/h. Four lasers quantify the longitudinal evenness of the road with submillimetre precision and kHz temporal resolution. A pavement profile scanner built by Fraunhofer IPM is used to measure the transverse evenness of the road with millimetre precision and a 2 MHz sampling rate. Two cameras and an illumination system provide continuous high-resolution and high-contrast images of the road surface for the quantification of the road condition. Furthermore, additional instruments are mounted for the surveying of road surroundings. A clearance profile scanner built by Fraunhofer IPM scans a 345° area perpendicular to the driving direction and delivers 3D data with millimetre precision. Four cameras acquire high-resolution images of the surrounding in all directions. In combination with a sophisticated post-processing pipeline, which extracts semantically segmented information from the images, this yields a digital, semantically interpreted representation of the mapped urban area.
• Bast H, Kalmbach J, Klumpp T, Kramer F, Schnelle N
  Efficient SPARQL Autocompletion via SPARQL
  2021 arXiv
  » show abstract« hide abstract
  Abstract

  We show how to achieve fast autocompletion for SPARQL queries on very large knowledge bases. At any position in the body of a SPARQL query, the autocompletion suggests matching subjects, predicates, or objects. The suggestions are context-sensitive in the sense that they lead to a non-empty result and are ranked by their relevance to the part of the query already typed. The suggestions can be narrowed down by prefix search on the names and aliases of the desired subject, predicate, or object. All suggestions are themselves obtained via SPARQL queries, which we call \emph{autocompletion queries}. For existing SPARQL engines, these queries are impractically slow on large knowledge bases. We present various algorithmic and engineering improvements of an existing SPARQL engine such that these autocompletion queries are executed efficiently. We provide an extensive evaluation of a variety of suggestion methods on three large knowledge bases, including Wikidata (6.9B triples). We explore the trade-off between the relevance of the suggestions and the processing time of the autocompletion queries. We compare our results with two widely used SPARQL engines, Virtuoso and Blazegraph. On Wikidata, we achieve fully sensitive suggestions with sub-second response times for over $90\%$ of a large and diverse set of thousands of autocompletion queries.
  
  
   
  Download file
• A. Premanand, F. Balle
  Development of ultrasonic fatigue system for testing hybrid materials
  2021 FMF Jahresbericht 2020
• F. Balle, B. Khatri
  Hybrid multifunctional composites (MCFRP): Metal and carbon fibers united!
  2021 FMF Jahresbericht 2020, Freiburger Materialforschungszentrum
• Wendler D, De Dorigo D, Amayreh M, Bleitner A, Marx M, Manoli Y
  A 0.00378mm2 Scalable Neural Recording Front-End for Fully Immersible Neural Probes Based on a Two-Step Incremental Delta-Sigma Converter with Extended Counting and Hardware Reuse
  2021 IEEE International Solid-State Circuits Conference (ISSCC)
• H. Nguyen, F. Lombeck, C. Schwarz, P. A. Heizmann, M. Adamski, H-F. Lee, B. Britton, S. Holdcroft, S. Vierrath, M. Breitwieser
  A fluorine-free hydrocarbon-based proton exchange membrane fuel cell with state-of-the-art performance
  2021 23rd European Fuel Cell Forum (EFCF), Lucerne, Switzerland (Online), 2.-5.07.2021
• Ashouri Vajari D, Vomero M, Coenen VA, Stieglitz T
  A stepping stone to enable preclinical evaluation of multimodal thin-film probes in small animal models
  2021 10th International IEEE/EMBS Conference in Neural Engineering (NER) 4-6 May 2021, Italy IEEE, pages: 132 - 135
  » show abstract« hide abstract
  Abstract

  The successful translation of novel implantable technologies to clinical applications demands the comprehensive preclinical evaluation of the devices in vivo. This work aims to facilitate such translation by proposing a miniaturized multimodal thin-film deep brain stimulation ( μ DBS) device, tailored to rodent anatomy. The device was realized by incorporating glassy carbon (GC) electrodes into a thin-film polyimide-based substrate. The finished probe featured nine GC active sites with diameters ranging from 50 μm to 300 μm. The performed fast scan cyclic voltammetry revealed a dopamine sensitivity of 12.63 ±2.19 nA μM -1 , 20.72±4.33 nA μM -1 , 135.44+8.24 nA μM -1 , and 68.50 ±3.42 μM -1 for electrodes with diameter of 50 μm, 100 μm, 200 μm, and 300 μm, respectively. The in vitro characterization assessed the μDBS probe's ability to address electrical stimulation - in addition to neurochemical sensing - in a single integrated device. Future evaluation of the μ-DBS probes as a multimodal platform in animal models remains to be the next step in this path.
• Manzouri F, Khurana L, Kravalis K, Stieglitz T, Schulze-Bonhage A, Dümpelmann M
  An Optimized EEG-Based Seizure Detection Algorithm for Implantable Devices
  2021 10th International IEEE/EMBS Conference in Neural Engineering (NER) 4-6 May 2021, Italy IEEE, pages: 995 - 998
  » show abstract« hide abstract
  Abstract

  A novel approach to the treatment of drug-resistant patients with epilepsy involves the use of implantable devices that deliver electrical stimulation to the epileptic focus at seizure onset. Accordingly, this process requires reliable and energy-efficient seizure detection. To this end, first, for finding the best match between the electrode configuration of an implantable device and the layout of electrodes used during long-term recordings for epilepsy diagnostics, we designed two automatic electrode selection methods. We next implemented four seizure detection algorithms, namely Random Forest (RF), Support Vector Machine (SVM), Multi-Layer Perceptron (MLP), and Convolutional Neural Network (CNN). We compared their performance using the automatically selected electrodes. The proposed CNN model showed the best performance, with a mean AUC-ROC (area under the receiver operating characteristic curve) score of 0.94. These results were obtained by applying just four channels with a limited spatial distribution. Therefore, automatic electrode selection methods enable an optimal training of the seizure detection algorithm. Besides, our newly designed seizure detection algorithm is a promising candidate for application in implantable devices.
• J.-N. Klatt, T.-L. Dinh, O. Schilling, R. Zengerle, F. Schmidt, T. Hutzenlaub, N. Paust
  Automation of Solid Phase Extraction for Peptide Desalting by Centrifugal Microfluidics
  2021 37th International Symposium on Microscale Separations and Bioanalysis 2021, Boston/USA (online), 12.-15.07.2021
• J.-N. Klatt, T.J. Dinh, N. Paust, R. Zengerle, F. Schmidt, O.Schilling, T. Hutzenlaub
  Automation of peptide desalting by centrifugal microfluidics
  2021 MicroTAS 2021, Palm Springs/USA, 10.-14.10.2021, online
• Lukas Mentel, Karsten Scheibler, Felix Winterer, Bernd Becker, Tino Teige
  Benchmarking SMT Solvers on Automotive Code
  2021 GI/ITG/GMM Workshop “Methoden und Beschreibungssprachen zur Modellierung und Verifikation von Schaltungen und Systemen”
  » show abstract« hide abstract
  Abstract

  Using embedded systems in safety-critical environments requires a rigorous testing of the components these systems are composed of. For example, the software running on such a system has to be evaluated regarding its code coverage – in particular, unreachable code fragments have to be avoided according to the ISO 26262 standard. Software model checking allows to detect such dead code automatically. While the recent case study [1] compares several academic software model checkers with the commercial test and verification tool BTC EmbeddedPlatform R (BTC EP), we want to focus on a lower level – i.e. the back-end solvers within BTC EP. Therefore, we evaluate the performance of off-the-shelf SMT solvers supporting the theory of floating-point as well as the theory of bitvectors on floating-point dominated benchmark instances originating from the automotive domain. Furthermore, we compare these off-the-shelf SMT solvers with the back-end solvers used by BTC EP.
• Klobasa M, Kühnbach M, Pelka S, Stute J, Sarfarazi S, Nienhaus K, Bruckmeier A, Springmann E, Köppl S, Guthoff F, Qussous R, Ritter D, Flachsbarth F, Heinemann C
  Bewertung der systemischen Auswirkungen der C/sells-Anwendungsfälle: Gesamtbericht der Arbeiten in Arbeitspaket 2.6 des SINTEG-Forschungsprojekts C/sells
  Fraunhofer ISI, 2021
• Kohler F, Hahn D, Schulz M, Fritze H, Wilde J
  Challenges for a High Temperature Glass Solder for the Assembly Concept of a Piezoelectric Resonator
  2021 Sensors
• Abunofal M, Poshiya N, Qussous R, Weidlich A
  Comparative Analysis of Electricity Market Prices Based on Different Forecasting Methods
  2021 IEEE Madrid PowerTech, volume: 2021
  
   
  Download file
• Huai H, Laskin G, Fratz M, Seyler T, Beckmann T, Bertz A, Wilde J
  Detecting Local Delamination of Power Electronic Devices Through Thermal-Mechanical Analysis
  2021 SMSI, Sensor and Measurement Science International
• B. Johannsen, D. Baumgartner, L. Karkossa, L. Müller, N. Paust, M. Karpíšek, N. Bostanci, R. Zengerle, K. Mitsakakis
  Detection of systemic and oral inflammation biomarkers through biochemical and microfluidic integration
  2021 MicroTAS 2021, Palm Springs/USA, 10.-14.10.2021, online
• D. Kainz, B. Breiner, R. Zengerle, N. Paust, T. Hutzenlaub, S. M. Früh
  Determining binding kinetics of a PCT lateral flow assay during runtime
  2021 MicroTAS 2021, Palm Springs/USA, 10.-14.10.2021, online
• P. Juelg, E. Kipf, M. Specht, J. Menges, M. Fillies, C. Eckert, N. Paust, R. Zengerle, M. Lehnert, T. Hutzenlaub
  Die MRD Disk: Automatisiertes Monitoring Minimaler Resterkrankung durch hochsensitive, zentrifugal-mikrofluidische Multiplex-qPCR / The MRD disk: automated minimal residual disease monitoring by highly sensitive centrifugal microfluidic multiplex qPCR
  2021 MST
• J. Weygant, F. Koch, K. Troendle, G. Finkenzeller, R. Zengerle, S. Kartmann, S. Zimmermann, P. Koltay
  Drop-on-Demand Bioprinting Approach For Precise Alignment and Interaction Studies of Different Cell Types
  2021 International Conference on Biofabrication, Australia, 27. – 29.09.2021 (online)
• K. Tröndle, A. Itani, F. Koch, R. Zengerle, P. Koltay, S. Zimmermann
  Drop-on-demand bioprinting solutions for the fabrication of 3D cell culture systems
  2021 DECHEMA 3D Cell Culture Freiburg (online), 05.-07.05.2021
• C. Schwarz, S. Vierrath, M. Breitwieser
  Elucidating the impact of Pt-ink ageing on fuel cell performance in laboratory scale CCM production
  2021 23rd European Fuel Cell Forum (EFCF), Lucerne, Switzerland (Online), 2.-5.07.2021
• van Dinther C, Flath CM, Gaerttner J, Huber J, Mengelkamp E, Schuller A, Staudt P, Weidlich A
  Engineering Energy Markets – The Past, the Present and the Future
  In: Market Engineering - Insights from Two Decades of Research on Markets and Information
  2021, Springer, pages: 113 - 134,
  » show abstract« hide abstract
  Abstract

  Since the beginning of energy sector liberalization, the design of energy markets has become a prominent field of research. Markets nowadays facilitate efficient resource allocation in many fields of energy system operation, such as plant dispatch, control reserve provisioning, delimitation of related carbon emissions, grid congestion management and, more recently, smart grid concepts and local energy trading. Therefore, good market designs play an important role in enabling the energy transition towards a more sustainable energy supply for all. In this contribution, we retrace how market engineering shaped the development of energy markets, and how the research focus shifted from national wholesale markets towards more decentralized and location-sensitive concepts.
• Huai H, Laskin G, Fratz M, Seyler T, Beckmann T, Bertz A, Carl D, Wilde J
  Evaluating Local Delamination of Power Electronic Devices Through Thermal-Mechanical Analysis
  2021 ,22nd International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems (EuroSimE)
• L. Niebling, S. Burger, N. Paust, A. R. Homann
  Fast and on-site animal species identification in processed meat
  2021 MicroTAS 2021, Palm Springs/USA, 10.-14.10.2021, online
• C. Klose, T. Saatkamp, A. Münchinger, L. Bohn, G. Titvinidze, M. Breitwieser, S. Vierrath,
  Fluorine-free membrane electrode assemblies for water electrolysis based on sulfonated polyphenylensulfone
  2021 23rd European Fuel Cell Forum (EFCF), Lucerne, Switzerland (Online), 2.-5.07.2021
• F. Schlenker, L. Karkossa, N. Paust, R. Zengerle, S. Giaglis, U. A. Walker, T. Hutzenlaub, P. Juelg
  Generation of platelet poor plasma for circulating cell-free mitochondrial DNA analysis on a centrifugal microfluidic platform
  2021 Micro and Nano Engineering Conference, Turin, Italy, 20. – 23.09.2021
• M. Schulz, J. Ruediger, E. Landmann, M. Bakheit, S. Frischmann, D. Rassler, A. R. Homann, F. von Stetten, R. Zengerle, N.Paust
  High dynamic range digital assay enabled by dual volume centrifugal step emulsification
  2021 MST-Kongress, Ludwigsburg, 08.-10.11.2021
• Laskin G, Huai H, Fratz M, Seyler T, Beckmann T, Schiffmacher A, Wilde J, Carl D
  High-speed electronic speckle pattern interferometry for analysis of thermo-mechanical behavior of electronic components
  2021 Optical Measurement Systems for Industrial Inspection XII (SPIE)
• E. Ortiz, F. Lombeck, M. Kroschel, J. Hübner, L. Bohn, M. von Holst, M. Breitwieser, P. Strasser, S. Vierrath
  Highly efficient low-loaded Ir-anodes proton exchange membrane water electrolysis: concepts to reduce in-plane resistance
  2021 23rd European Fuel Cell Forum (EFCF), Lucerne, Switzerland (Online), 2.-5.07.2021
• Schulz M, Kohler F, Wilde J, Fritze H
  Housed Temperature Sensors Based on Piezoelectric Resonators for High-Temperature Applications
  2021 SMSI, Sensor and Measurement Science International
• Z. Khan, Z. Shu, R. Zengerle, P. Koltay
  Hybrid 3D printing of polymer and solder to create functional 3D electronics
  2021 EPoSS Annual Forum 2021, Freiburg, 04.-07.10.2021
• F. Koch, K. Tröndle, G. Finkenzeller, P. Rukavina, R. Zengerle, P. Koltay, S. Zimmermann
  Hybrider 3D-Biodruck zur künstlichen Herstellung von Knochen / Using hybrid processes for 3D-bioprinting of artificial bone tissue
  2021 MST-Kongress, Ludwigsburg, 08.-10.11.2021
• Karsten Scheibler, Felix Winterer, Tobias Seufert, Tino Teige, Christoph Scholl, Bernd Becker
  ICP and IC3
  2021 Conference on Design, Automation and Test in Europe Conference (DATE)
  » show abstract« hide abstract
  Abstract

  If embedded systems are used in safety-critical environments, they need to meet several standards. For example, in the automotive domain the ISO 26262 standard requires that the software running on such systems does not contain unreachable code. Software model checking is one effective approach to automatically detect such dead code. Being used in a commercial product, iSAT3 already performs very well in this context. In this paper we integrate IC3 into iSAT3 in order to improve its dead code detection capabilities even further.
• Karsten Scheibler, Felix Winterer, Tobias Seufert, Tino Teige, Christoph Scholl, Bernd Becker
  ICP and IC3
  2021 DATE, IEEE
  » show abstract« hide abstract
  Abstract

  If embedded systems are used in safety-critical environments,they need to meet several standards. For example, in the automotive domain the ISO 26262 standard requires that the software running on such systems does not contain unreachable code. Software model checking is one effective approach to automatically detect such dead code. Being used in a commercial product, iSAT3 already performs very well in this context. In this paper we integrate IC3 into iSAT3 in order to improve its dead code detection capabilities even further.
• Felix Winterer, Tobias Seufert, Karsten Scheibler, Tino Teige, Christoph Scholl, Bernd Becker
  ICP and IC3 with Stronger Generalization
  2021 GI/ITG/GMM Workshop “Methoden und Beschreibungssprachen zur Modellierung und Verifikation von Schaltungen und Systemen”
  » show abstract« hide abstract
  Abstract

  Most recently, IC3 was integrated into the SMT solver iSAT3. Thus, iSAT3+IC3 introduces the first IC3 variant based on interval abstraction and Interval Constraint Propagation (ICP). As strong generalization is one of the key aspects for the IC3 algorithm to be successful, we integrate two additional generalization schemes from literature into iSAT3+IC3: Inductive Generalization and Counterexamples To Generalization (CTG). Furthermore, we evaluate the benefits and the drawbacks of different variants of these methods in the context of interval abstraction and ICP.
• Felix Winterer, Tobias Seufert, Karsten Scheibler, Tino Teige, Christoph Scholl, Bernd Becker
  ICP and IC3 with Stronger Generalization
  2021 MBMV
  » show abstract« hide abstract
  Abstract

  Most recently, IC3 was integrated into the SMT solver iSAT3. Thus, iSAT3+IC3 introduces the first IC3 variant based on interval abstraction and Interval Constraint Propagation (ICP). As strong generalization is one of the key aspects for the IC3 algorithm to be successful, we integrate two additional generalization schemes from literature into iSAT3+IC3: Inductive Generalization and Counterexamples To Generalization (CTG). Furthermore, we evaluate the benefits and the drawbacks of different variants of these methods in the context of interval abstraction and ICP.
• S. Koch, S. K. Kilian, P. A. Heizmann, M. Breitwieser, S. Vierrath
  Improving anion-exchange-membrane water electrolyzers by adjusting the ionomer content in the catalyst layers
  2021 23rd European Fuel Cell Forum (EFCF), Lucerne, Switzerland (Online), 2.-5.07.2021
• Schiffmacher A, Malasani S, Kempiak C, Lindemann A, Wilde J
  In-situ Degradationserfassung mittels Lock-In Thermographie während aktiver Lastwecheltests
  2021 50. Kolloquium Leistungshalbleiter-Bauelemente und ihre systemtechnische Integration
• Weidlich A
  Infrastrukturen für ein klimaneutrales Energiesystem: Szenarienstudien weisen den Weg
  Stiftung Energie und Klimaschutz, 2021
• H. C. Ates, A. Brunauer, F. von Stetten, G. A. Urban, F. Güder, A. Merkoçi, S. M. Früh, C. Dincer
  Integrated Devices for Non‐Invasive Diagnostics
  2021 Advanced Functional Materials, volume: 31, issue: 15, page: 2010388
  » show abstract« hide abstract
  Abstract

  “Sample‐in‐answer‐out” type integrated diagnostic devices have been widely recognized as the ultimate solution to simplify testing across healthcare systems. Such systems are equipped with advanced fluidic, mechanical, chemical, biological, and electronic components to handle patient samples without any manual steps therefore have the potential to accelerate intervention and improve patient outcomes. In this regard, the combination of integrated devices and non‐invasive sampling has gained a substantial interest to further improve the comfort and safety of patients. In this Review, the pioneering developments in integrated diagnostics are covered and their potential in non‐invasive sampling is discussed. The key properties of possible sample types are highlighted by addressing their relevance for the clinical practice. Last, the factors affecting the transition of integrated devices from academia to the market are identified by analyzing the technology readiness levels of selected examples and alternative remedies are explored to increase the rate of survival during this transition.
• M. Trotter, D. Juric, Z. Bagherian, N. Borst, K. Gläser, F. von Stetten, A. Zimmermann
  Integration of nanoporous gold electrodes in microfluidic chambers by inkjet-printing for biosensing applications
  2021 MST-Kongress, Ludwigsburg, 08.-10.11.2021
• J. Schlanderer, J. Lüddecke, R. Zengerle, N. Paust
  Large sample volume management on centrifugal microfluidic cartridges
  2021 Micro and Nano Engineering Conference, Turin, Italy, 20. – 23.09.2021
• P. A. Heizmann, M. von Holst, H. Nguyen, F. Lombeck, C. Schwarz, C. Klose, M. Breitwieser, S. Vierrath
  Linking morphological properties of Pt/C catalysts to electrochemical performances for improved catalysis in fuel cells
  2021 23rd European Fuel Cell Forum (EFCF), Lucerne, Switzerland (Online), 2.-5.07.2021
• Gimpel H, Krämer J, Neumann D, Pfeiffer J, Seifert S, Teubner T, Veit DJ, Weidlich A
  Market Engineering - Insights from Two Decades of Research on Markets and Information
  2021 Springer
• Kohler F, Farina M, Zeitouny Z, Schulz M, Fritze H, Wilde J
  Materialien und Prozesse für zuverlässige Aufbautechnologien von piezoelektrischen Sensorelementen bis 1000 °C
  2021 4. Symposium Materialtechnik und e-Conference des Clausthaler Zentrum für Materialtechnik
• D. Baumgartner, B. Johannsen, N. Paust, F. von Stetten, R. Zengerle, K. Mavridis, J. Vontas, K. Mitsakakis
  Microfluidic-based molecular analysis of plant psts for insecticide resistance management (Superpests-Disk)
  2021
• Pascal Pieper, Ralf Wimmer, Gerhard Angst, Rolf Drechsler
  Minimally Invasive HW/SW Co-debug Live Visualization on Architecture Level
  2021 ACM Press
  » show abstract« hide abstract
  Abstract

  We present a tool that allows developers to debug hard- and software and their interaction in an early design stage. We combine a SystemC virtual prototype (VP) with an easily configurable and interactive graphical user interface and a standard software debugger. The graphical user interface visualizes the internal state of the hardware. At the same time, the software debugger monitors and allows to manipulate the state of the software. This co-visualization supports design understanding and live debugging of the HW/SW interaction. We demonstrate its usefulness with a case-study where we debug an OLED display driver running on a RISC-V VP.
• A. Brunauer, A.-S. Kittel, R. D. Verboket, F. von Stetten, S. M. Früh
  Multianalyte-Assays: Simultaneous detection of protein and nucleic acid biomarkers
  2021 European Biosensor Symposium (EBS), online, 09.-12.03.2021
• A.-S. Kittel, R. D. Verboket, F. von Stetten, S. M. Früh
  Multianalyte-Assays: Simultaneous detection of protein and nucleic acid biomarkers
  2021 European Biosensor Symposium (EBS), online, 09.-12.03.2021
• Coenen C, Stieglitz T
  Neurotech-Ethics: Suggestions for the Way Forward
  2021 10th International IEEE/EMBS Conference in Neural Engineering (NER) 4-6 May 2021, Italy IEEE, pages: 639 - 642
  » show abstract« hide abstract
  Abstract

  In recent years, the ethics of neurotechnology are emerging as a major area of research within neuroethics. In this paper, we comment on the state of the art and discussions in this area, addressing a number of key questions and making suggestions for the way forward concerning certain under-appreciated aspects. We argue that for embedding new, emerging and future neurotechnologies in society, interactions between the various stakeholder groups and their interests should be analyzed in more detail, and the spectrum of involved stakeholder groups as well as the thematic scope of activities and discussions should be broadened.
• Tobias Paxian, Pascal Raiola, Bernd Becker
  On Preprocessing for Weighted MaxSAT
  2021 VMCAI - 22nd International Conference on Verification, Model Checking, and Abstract Interpretation, Springer, volume: 12597, pages: 556 - 577
  » show abstract« hide abstract
  Abstract

  Modern competitive solvers employ various preprocessing techniques to efficiently tackle complex problems. This work introduces two preprocessing techniques to improve solving weighted partial MaxSAT problems: Generalized Boolean Multilevel Optimization (GBMO) and Trimming MaxSAT (TrimMaxSAT). GBMO refines and extends Boolean Multilevel Optimization (BMO), thereby splitting instances due to their distribution of weights into multiple less complex subproblems, which are solved one after the other to obtain the overall solution. The second technique, TrimMaxSAT, finds unsatisfiable soft clauses and removes them from the instance. This reduces the complexity of the MaxSAT instance and works especially well in combination with GBMO. The proposed algorithm works incrementally in a binary search fashion, testing the satisfiability of every soft clause. Furthermore, as a by-product, typically an initial weight close to the maximum is found, which is in turn advantageous w.r.t. the size of e.g. the Dynamic Polynomial Watchdog (DPW) encoding. Both techniques can be used by all MaxSAT solvers, though our focus lies on Pseudo Boolean constraint based MaxSAT solvers. Experimental results show the effectiveness of both techniques on a large set of benchmarks from a hardware security application and from the 2019 MaxSAT Evaluation. In particular for the hardest of the application benchmarks, the solver Pacose with GBMO and TrimMaxSAT performs best compared to the MaxSAT Evaluation solvers of 2019. For the benchmarks of the 2019 MaxSAT Evaluation, we show that with the proposed techniques the top solver combination solves significantly more instances.
• Bielefeldt S, Stieglitz T, Eickenscheidt M
  On the Stability of Porous Platinum Coatings for In-Ear EEG Applications
  2021 10th International IEEE/EMBS Conference on Neural Engineering (NER) 4-6 May 2021, Italy IEEE, pages: 601 - 604
  » show abstract« hide abstract
  Abstract

  Challenging applications, like in-ear electroencephalography (EEG), call for small electrode geometries with a large active area. Porous platinum (pPt) coating is a promising candidate, whereby the stability and reusability remain pressing manners. Here, different seeding layers were examined to find the most stable base substrate. In all cases the pPt reduced the impedance by two orders of magnitude in the low frequency region (<; 100 Hz), and the atomic concentration of platinum was preserved with 85%wt. Roughening of the materials by hatching or using medical alloys like MP35N leads to increased abrasion after peeling tests. Smooth platinum or platinum-iridium (90/10) performed best and withstood up to 2 MPa peeling force.
• Y.-T. Kao, S. Calabrese, N. Borst, M. Lehnert, Y.-K. Lai, F. Schlenker, R. Zengerle, P. Garstecki, F. von Stetten
  One-step amplification-free bacteria detection by optimizes LNA/DNA molecular beacons in droplets
  2021 MicroTAS 2021, Palm Springs/USA, 10.-14.10.2021, online
• L. Becherer, J.F. Hess, S. Frischmann, M. Bakheit, H. Nitschko, S. Stinco, F. Zitz, H. Hofer, G. Porro, F. Hausladen, K. Stock, D. Drossart, H. Wurm, H. Kuhn, D. Huber, T. Hutzenlaub, N. Paust, M. Keller, O. Strohmeier, S. Wadle, N. Borst, R. Zengerle, F. von Stetten
  Point-of-Care System for HTLV-1 Proviral Load Quantification by Digital Mediator Displacement LAMP
  2021 MST-Kongress, Ludwigsburg, 08.-10.11.2021
• Weidlich A, Neumann D, Gust G, Staudt P, Schäfer M
  Proceedings of the 10th DACH+ Conference on Energy Informatics
  2021 SpringerOpen
• A. Brunauer, R. D. Verboket, D. M. Kainz, F. von Stetten, S. M. Früh
  Rapid nucleic acid lateral flow immunoassay for the detection of Pseudomonas aeruginosa
  2021 Biosensors 2021, Haeundae-gu, South Korea, (online), 26. - 29.07.2021
• K. Seteiz, B. Shanahan, P. A. Heizmann, S. Koch, J. Büttner, S. Ouardi, S. Vierrath, A. Fischer, M. Breitwieser
  Rapid wet-chemical oxidative activation of graphite felt electrodes for vanadium redox flow batteries
  2021 2nd Electrochemical Cell Concepts Colloquium (Virtual E3C), Oberhausen, Germany (Online), 6.5.2021
• Hallak A, Mathpati M, Wilde J
  Self-Healing Mechanisms in Thermoplastic, Media-Tight Injection-Molded Housings
  2021 44th International Spring Seminar on Electronics Technology (ISSE)
• A. Klebes, A.-S. Kittel, R. D. Verboket, F. von Stetten, S. M. Früh
  Simultaneous detection of protein and nucleic acid biomarkers via paper-based multianalyte sensor
  2021 MicroTAS 2021, Palm Springs/USA, 10.-14.10.2021, online
• Aile Ge-Ernst, Christoph Scholl, Ralf Wimmer
  Solving Dependency Quantified Boolean Formulas Using Quantifier Localization
  CoRR, volume: 1905.04755, 2021
• D. Baumgartner, B. Johannsen, N. Paust, F. von Stetten, R. Zengerle, K. Mavridis, J. Vontas, K. Mitsakakis
  SuperPests LabDisk: a microfluidic-based molecular diagnostic platform for detection of biotypes, resistance mutations and plant pathogens P3.021
  2021 Biosensors, Haeundae-gu, South Korea (online), 26. – 29.07.2021
• S. Vierrath, E. Cruz Ortiz, F. Hegge, T. Böhm, F. Lombeck, M. Breitwieser
  Tackling durability and efficiency in polymer membrane fuel cells and electrolysis
  2021 MRS Seattle/Washington, USA (online), 10. – 14.04.2021
• Marc Pfeifer, Benjamin Völker, Sebastian Böttcher, Sven Köhler, Philipp M Scholl
  Teaching Embedded Systems by Constructing an Escape Room
  2021 In Proceedings of the 52nd ACM Technical Symposium on Computer Science Education (SIGCSE ’21), Virtual Event, New York, USA ACM
  » show abstract« hide abstract
  Abstract

  Embedded systems form the basis of many of today's consumer products and industrial applications - and they are increasingly connected. To teach this topic, we created a course with the overarching goal of designing and constructing an automated escape room. This provided the motivation for the students to learn the engineering and soft skills required for building networked embedded systems. The game was open for faculty members and friends of the students after course completion. By splitting the building process into multiple tasks, such as individual puzzles, the presented concept encourages inter- and intra-group work, including conceptualizing, designing and developing reliable, connected embedded systems. In this paper we first present the motivation, context, and pedagogical approach of the course. We then describe the course structure and conclude with experiences from constructing an escape room as a group.
  
  
   
  Download file
• P. A. Heizmann, M. von Holst, F. Lombeck, H. Nguyen, C. Klose, M. Breitwieser, S. Vierrath
  Understanding the platinum carbon-support interaction for improved catalysis in hydrogen fuel cells
  2021 9th NRW Nano Conference: Innovations in Materials and Applications, Münster, Germany (Online), 21.-23.04.2021
• T. Härpfer, L. Becherer, M. Bakheit, S. Frischmann, S. Stinco, N. Borst, R. Zengerle, F. von Stetten
  Universal multiplex mediator displacement LAMP Nr. P3.062 analytical and clinical validation on the example of HIV, Haemophilus ducreyi and Treponema pallidum
  2021 Biosensors, , Haeundae-gu, South Korea (online) , 26. – 29.07.2021
• Christoph Scholl, Alexander Konrad, Alireza Mahzoon, Daniel Große, Rolf Drechsler
  Verifying Dividers Using Symbolic Computer Algebra and Don’t Care Optimization
  2021 DATE, IEEE
  » show abstract« hide abstract
  Abstract

  In this paper we build on methods based on Symbolic Computer Algebra that have been applied successfully to multiplier verification and more recently to divider verification as well. We show that existing methods are not sufficient to verify optimized non-restoring dividers and we enhance those methods by a novel optimization method for polynomials w. r. t. satisfiability don’t cares. The optimization is reduced to Integer Linear Programming (ILP). Our experimental results show that this method is the key for enabling the verification of large and optimized non-restoring dividers (with bit widths up to 512).
• E. Mahmodi Arjmand, G. Grether, R. Zengerle, N. Paust, J. Lüddecke
  Waste liquid assisted flow-switching on a centrifugal microfluidic platform
  2021 Micro and Nano Engineering Conference, Turin, Italy, 20. – 23.09.2021
• Sauer DU, Pittel K, Henning H-M, Renn J, Schmidt C, Spiecker I, Bett A, Haucap J, Kühling J, Matthies E, Umbach E, Ragwitz M, Staiß F, Weidlich A, Erlach B, Glotzbach U, Lapac A, Seiler A, Stephanos C
  Wenn nicht jetzt, wann dann – wie die Energiewende gelingt
  acatech Schriftenreihe zur wissenschaftsbasierten Politikberatung, 2021

2020

 back to the year overview

• Bast H, Brosi P, Näther M
  Similarity Classification of Public Transit Stations
  2020 arXiv
  » show abstract« hide abstract
  Abstract

  We study the following problem: given two public transit station identifiers and , each with a label and a geographic coordinate, decide whether and describe the same station. For example, for "St Pancras International" at (51.5306, −0.1253) and "London St Pancras" at (51.5319, −0.1269), the answer would be "Yes". This problem frequently arises in areas where public transit data is used, for example in geographic information systems, schedule merging, route planning, or map matching. We consider several baseline methods based on geographic distance and simple string similarity measures.We also experiment with more elaborate string similarity measures and manually created normalization rules. Our experiments show that these baseline methods produce good, but not fully satisfactory results. We therefore develop an approach based on a random forest classifier which is trained on matching trigrams between two stations, their distance, and their position on an interwoven grid. All approaches are evaluated on extensive ground truth datasets we generated from OpenStreetMap (OSM) data: (1) The union of Great Britain and Ireland and (2) the union of Germany, Switzerland, and Austria. On all datasets, our learning based approach achieves an F1 score of over 99%, while even the most elaborate baseline approach (based on TFIDF scores and the geographic distance) achieves an F1 score of at most 94%, and a naive approach of using a geographical distance threshold achieves an F1 score of only 75%. Both our training and testing datasets are publicly available1.
  
  
   
  Download file as PDF
• Bast H, Brosi P, Näther M
  staty: Quality Assurance for Public Transit Stations in OpenStreetMap
  2020 Sigspatial
  » show abstract« hide abstract
  Abstract

  We present staty, a browser-based tool for quality assurance of public transit station tagging in OpenStreetMap (OSM). Building on the results of a similarity classifier for these stations, our tool visualizes name tag errors as well as incorrect and/or missing station group relations. Detailed edit suggestions are provided for individual objects. This is done intrinsically without an external ground truth. Instead, the underlying classifier is trained on the OSM data itself. We describe how our tool derives errors and suggestions from station tag similarities and provide experimental results on the OSM data of the United Kingdom, the United States, and a dataset consisting of Germany, Switzerland, and Austria. Our tool can be accessed under https://staty.cs.uni-freiburg.de.
• Unnewehr J
  Tracking CO2 emissions from power generation in high spatial and temporal resolution – Case study for the German electricity system
  2020 Energy Informatics, volume: 3
  » show abstract« hide abstract
  Abstract

  Until today it is not possible to allocate the CO2 emissions in the German electricity system to a specific region and its corresponding electricity demand that caused them. This paper presents a new energy system model and uses established methods for answering this question. A detailed bottom-up model of the German electricity system is built to represent a highly spatial and temporal representation of the Germany electricity system in 2019. In combination with a customized input-output analysis, the individual emissions from the producer to the caused consumer can be traced. The analysis demonstrates the importance of considering spatial and temporal effects as well as electricity exchanges between regions in estimating emissions footprints.
• Bast H, Hertel M, Mostafa M
  Tokenization Repair in the Presence of Spelling Errors
  2020 arXiv
  » show abstract« hide abstract
  Abstract

  We consider the following tokenization repair problem: Given a natural language text with any combination of missing or spurious spaces,correct these. Spelling errors can be present,but it’s not part of the problem to correct them. For example, given: “Tispa per is about tokenizaion repair”, compute “Tis paper is about tokenizaion repair”.It is tempting to think of this problem as a special case of spelling correction or to treat the two problems together. We make a case that tokenization repair and spelling correction should and can be treated as separate problems.We investigate a variety of neural models as well as a number of strong baselines. We identify three main ingredients to high-quality tokenization repair: deep language models with a bidirectional component, training the models on text with spelling errors, and making use of the space information already present.Our best methods can repair all tokenization errors on 97.5% of the correctly spelled test sentences and on 96.0% of the misspelled test sentences. With all spaces removed from the given text (the scenario from previous work),the accuracy falls to 94.5% and 90.1%, respectively. We conduct a detailed error analysis.
  
  
   
  Download file
• Merkle, Dominik, Schmitt, Annette, Reiterer, Alexander
  Concept of an autonomous mobile robotic system for bridge inspection
  2020 Conference "Remote Sensing Technologies and Applications in Urban Environments" <5, 2020 SPIE, SPIE, 2020 (Proceedings of SPIE 11535) Paper 115350A
  » show abstract« hide abstract
  Abstract

  Fraunhofer-Gesellschaft Concept of an autonomous mobile robotic system for bridge inspection Autor(en): Merkle, Dominik; Schmitt, Annette; Reiterer, Alexander Zugang: Postprint urn:nbn:de:0011-n-6032527 (17 MByte PDF) MD5 Fingerprint: 5cbbff9ccf7e32d405c888142f2850d4 Copyright Society of Photo-Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited. Erstellt am: 9.10.2020 DOI: 10.1117/12.2570633 [Titel anhand dieser DOI in Citavi-Projekt übernehmen] Quelle Society of Photo-Optical Instrumentation Engineers -SPIE-, Bellingham/Wash.: Remote Sensing Technologies and Applications in Urban Environments V : 21-25 September 2020, Online Only Bellingham, WA: SPIE, 2020 (Proceedings of SPIE 11535) Paper 115350A, 16 S. Konferenz Conference "Remote Sensing Technologies and Applications in Urban Environments" <5, 2020, Online> Sprache Englisch Dokumentart Konferenzbeitrag, Elektronische Publikation Fraunhofer Institut Fraunhofer IPM (Institutshomepage) Schlagwörter mobile mapping; LiDAR; bridge inspection; sensor system; mobile robot Abstract In the next decade, many old bridges will be exposed to increasing traffic loads and destructive environmental conditions. Measurement methods like laser scanning, infrared thermography, photogrammetry, ground penetrating radar, or ultrasonic scanning are used on single robotic systems to partially support the inspectors. However, time-consuming manual inspections for crack detection, measurement, and documentation are still necessary. This paper describes the concept of an autonomous mobile robotic bridge inspection system. The proposed concept for an unmanned ground vehicle (UGV) is achieved by a trade-off of different mobile platforms, sensor systems for mapping, localization and inspection, and fist tests assessing the feasibility. We use a small concrete bridge in Freiburg (Germany) with various cracks for testing the sensors, the UGV concept, and initial tests of the mobile platform. This results in the choice of selecting the weatherproof version of the mobile robotic platform Husky from Clearpath Robotics. It is equipped with Swift Navigation's Duro real-time kinematic (RTK) system, a heading system, an inertial measurement unit (IMU), a base station, and software for semi-autonomous navigation. In the next step, we compare different sensor systems. For mapping and localization, we decide to use the 360 spherical camera Ladybug 5+ from FLIR Systems and a Velodyne VLP-16 light detection and ranging (LiDAR). High-resolution cameras allow recording damages on the bridge's surface. We perform first tests using monochrome and colour cameras. After evaluating different sensor integration concepts, we present a preliminary design of the UGV including integrated sensors.
  
  
   
  Download file
• Magnús M. Halldórsson, Fabian Kuhn, Yannic Maus, Alexandre Nolin
  Coloring Fast Without Learning Your Neighbors' Colors.
  2020 34rd International Symposium on Distributed Computing (DISC)
  » show abstract« hide abstract
  Abstract

  We give an improved randomized CONGEST algorithm for distance-2 coloring that uses Δ²+1 colors and runs in O(log n) rounds, improving the recent O(log Δ ⋅ log n)-round algorithm in [Halldórsson, Kuhn, Maus; PODC '20]. We then improve the time complexity to O(log Δ) + 2^{O(√{log log n})}.
• Fabian Kuhn, Philipp Schneider
  Computing Shortest Paths and Diameter in the Hybrid Network Model.
  2020 39th ACM Symposium on Principles of Distributed Computing (PODC)
  » show abstract« hide abstract
  Abstract

  The HYBRID model, introduced in [Augustine et al., SODA '20], provides a theoretical foundation for networks that allow multiple communication modes. The model follows the principles of synchronous message passing, whereas nodes are allowed to use two fundamentally different communication modes. First, a local mode where nodes may exchange arbitrary information per round over edges of a local communication graph G (akin to the LOCAL model). Second, a global mode where every node may exchange O(log n) messages of size O(log n) bits per round with arbitrary nodes in the network. The HYBRID model intends to reflect the conditions of many real hybrid networks, where high-bandwidth but inherently local communication is combined with highly flexible global communication with restricted bandwidth. We continue to explore the power and limitations of the HYBRID model by investigating the complexity of computing shortest paths and diameter of the local communication graph G. We show that the all pair shortest paths problem can be solved exactly in [EQUATION] rounds, which improves on the previous Õ(n2/3) round algorithm and closes the gap to the known [EQUATION] lower bound (up to polylog n factors). Furthermore, we give constant approximations for the k-source shortest paths problem (k-SSP) with runtime [EQUATION], provided that k is sufficiently large. As k-SSP has a lower bound of [EQUATION] even for large approximation ratios, our k-SSP algorithms are almost tight for large enough k. In the case of a single source we give an exact Õ(n2/5)-round algorithm, improving on the known [EQUATION]-round algorithm for graphs with large diameter D. For the diameter problem we provide algorithms with complexities Õ(n1/3/ε) and Õ(n0.397/ε) and approximation factors (3/2 + ε) and (1 + ε), respectively. On the negative side, we demonstrate that the classical 2-party set-disjointness framework can be adapted for the HYBRID model to prove a lower bound of [EQUATION] rounds for computing the diameter exactly. For the weighted diameter problem the same holds for computing (2 − ε)-approximations for any ε > 0.
• Magnús M. Halldórsson, Fabian Kuhn, Yannic Maus
  Distance-2 Coloring in the CONGEST Model.
  2020 39th ACM Symposium on Principles of Distributed Computing (PODC)
  » show abstract« hide abstract
  Abstract

  We give efficient randomized and deterministic distributed algorithms for computing a distance-2 vertex coloring of a graph G in the CONGEST model. In particular, if Δ is the maximum degree of G, we show that there is a randomized CONGEST model algorithm to compute a distance-2 coloring of G with Δ2 + 1 colors in O(log Δ · log n) rounds. Further if the number of colors is slightly increased to (1 + ∈)Δ2 for some ∈ > 1/polylog n, we show that it is even possible to compute a distance-2 coloring deterministically in polylog n time in the CONGEST model. Finally, we give a O(Δ2 + log* n)-round deterministic CONGEST algorithm to compute distance-2 coloring with Δ2 + 1 colors.
• Alkida Balliu, Fabian Kuhn, Dennis Olivetti
  Distributed Edge Coloring in Time Quasi-Polylogarithmic in Delta.
  2020 39th ACM Symposium on Principles of Distributed Computing (PODC)
  » show abstract« hide abstract
  Abstract

  The problem of coloring the edges of an n-node graph of maximum degree Δ with 2Δ − 1 colors is one of the key symmetry breaking problems in the area of distributed graph algorithms. While there has been a lot of progress towards the understanding of this problem, the dependency of the running time on Δ has been a longstanding open question. Very recently, Kuhn [SODA '20] showed that the problem can be solved in time [EQUATION]. In this paper, we study the edge coloring problem in the distributed LOCAL model. We show that the (degree + 1)-list edge coloring problem, and thus also the (2Δ − 1)-edge coloring problem, can be solved deterministically in time 2O(log2 log Δ)+O(log*n). This is a significant improvement over the result of Kuhn [SODA '20].
• Mohamad Ahmadi, Fabian Kuhn
  Distributed Maximum Matching Verification in CONGEST
  2020 34rd International Symposium on Distributed Computing (DISC)
  » show abstract« hide abstract
  Abstract

  We study the maximum cardinality matching problem in a standard distributed setting, where the nodes V of a given n-node network graph G = (V,E) communicate over the edges E in synchronous rounds. More specifically, we consider the distributed CONGEST model, where in each round, each node of G can send an O(log n)-bit message to each of its neighbors. We show that for every graph G and a matching M of G, there is a randomized CONGEST algorithm to verify M being a maximum matching of G in time O(|M|) and disprove it in time O(D + ), where D is the diameter of G and is the length of a shortest augmenting path. We hope that our algorithm constitutes a significant step towards developing a CONGEST algorithm to compute a maximum matching in time Õ(s^*), where s^* is the size of a maximum matching.
• Philipp Bamberger, Fabian Kuhn, Yannic Maus
  Efficient Deterministic Distributed Coloring with Small Bandwidth.
  2020 39th ACM Symposium on Principles of Distributed Computing (PODC)
  » show abstract« hide abstract
  Abstract

  We show that the (degree + 1)-list coloring problem can be solved deterministically in O(D · log n · log2 Δ) rounds in the CONGEST model, where D is the diameter of the graph, n the number of nodes, and Δ the maximum degree. Using the recent polylogarithmic-time deterministic network decomposition algorithm by Rozhoň and Ghaffari [49], this implies the first efficient (i.e., poly log n-time) deterministic CONGEST algorithm for the (Δ + 1)-coloring and the (degree + 1)-list coloring problem. Previously the best known algorithm required [EQUATION] rounds and was not based on network decompositions. Our techniques also lead to deterministic (degree + 1)-list coloring algorithms for the congested clique and the massively parallel computation (MPC) model. For the congested clique, we obtain an algorithm with time complexity O(log Δ · log log Δ), for the MPC model, we obtain algorithms with round complexity O(log2 Δ) for the linear-memory regime and O(log2 Δ + log n) for the sublinear memory regime.
• D. Merkle;, A. Schmitt;, A. Reiterer
  SENSOR EVALUATION FOR CRACK DETECTION IN CONCRETE BRIDGES
  2020 Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci., pages: 1107 - 1114
  » show abstract« hide abstract
  Abstract

  Bridges are one of the most critical traffic infrastructure objects, therefore it is necessary to monitor them at regular intervals. Nowadays, this monitoring is made manually by visual inspection. In recent projects, the authors are developing automated crack detection systems to support the inspector. In this pre-study, different sensors, like different camera systems for photogrammetry, a laser scanner, and a laser triangulation system are evaluated for crack detection based on a defined required minimum crack width of 0.2 mm. The used test object is a blasted concrete plate, sized 70 cm × 70 cm × 5 cm and placed in an outdoor environment. The results of the data acquisition with the different sensors are point clouds, which make the results comparable. The point cloud from the chosen laser scanner is not sufficient for the required crack width even at a low speed of 1 m/s. The RGB or intensity information of the photogrammetric point clouds, even based on a low-cost smartphone camera, contain the targeted cracks. The authors advise against using only the 3D information of the photogrammetric point clouds for crack detection due to noise. The laser triangulation system delivers the best results in both intensity and 3D information. The low weight of camera systems makes photogrammetry to the preferred method for an unmanned aerial vehicle (UAV). In the future, the authors aim for crack detection based on the 2D images, automated by using machine learning, and crack localisation by using structure from motion (SfM) or a positioning system.
  
  
   
  Download file
• Bast H, Brosi P, Storandt S
  Metro Maps on Octilinear Grid Graphs
  2020 EuroVis Eurographics Conference on Visualization, volume: 39, issue: 3
  » show abstract« hide abstract
  Abstract

  Schematic transit maps (often called "metro maps" in the literature) are important to produce comprehensible visualizations ofcomplex public transit networks. In this work, we investigate the problem of automatically drawing such maps on an octilineargrid with an arbitrary (but optimal) number of edge bends. Our approach can naturally deal with obstacles that should berespected in the final drawing (points of interest, rivers, coastlines) and can prefer grid edges near the real-world course of aline. This allows our drawings to be combined with existing maps, for example as overlays in map services. We formulate aninteger linear program which can be used to solve the problem exactly. We also provide a fast approximation algorithm whichgreedily calculates shortest paths between node candidates on the underlying octilinear grid graph. Previous work used localsearch techniques to update node positions until a local optimum was found, but without guaranteeing octilinearity. We canthus calculate nearly optimal metro maps in a fraction of a second even for complex networks, enabling the interactive use ofour method in map editors
• Ruther P
  LED-based optogenetic tools - Thin-film LEDs vs LED chips
  2020 Bionics Institute Melbourne, Melbourbe, Australia; Remote seminar talk
• Ruther P, Ayub S, Klein E, Sharma K, Paul O
  LED-Based Optogenetic Tools - Are Smallest LEDs Always Requested and Reasonable?
  2020 ICAN Workshop 2./3.3.2020, College of Health and Life Sciences at Hamad Bin Khalifa University, Doha, Qatar
  
   
  Download file as PDF
• Vilches S, Ataman C, Zappe H
  Non-contact endoscopic temperature measurement
  2020 Proceedings of SPIE, volume: 11233
• Feißt M, Wilde J
  Niedertemperatur-Verbindungstechnik für MEMS-Sensorbauelemente
  2020 Elektronische Baugruppen und Leiterplatten EBL 2020, Fellbach, ISBN 978-3-8007-5185-3, VDE VERLAG GMBH, volume: 94, pages: 199 - 203
• Kohler F, Wilde J
  Untersuchung der Einflussfaktoren zur Industrialisierung der Prozesse beim mediendichten Umspritzen von mechatronischen Komponenten
  2020 Elektronische Baugruppen und Leiterplatten EBL 2020, Fellbach, ISBN 978-3-8007-5185-3, VDE VERLAG GMBH, volume: 94, pages: 114 - 118
• Stieglitz T, Cvancara P, Mueller M, Ordonez JS
  Minaturized neural implants: towards longevity of compound systems.
  2020 Wissenschaftliches Symposium zur Einweihung des 3000. FIB/SEM Gerätes der Firma TESCAN am IMTEK , 11.02.2020, Freiburg (2020).
• Stieglitz T, Cvancara P, Mueller M, Liljemalm R, Erhardt J, Boehler C, Pfau J, Fiedler E, Ashouri Vajari D, Vomero M, Oliveira A, Kan S, Kiele P, Langenmair M, Pasluoasta C, Eickenscheidt M, Asplund M, Ordonez JS
  Miniaturized neural implants for interfacing with the brain
  2020 6th CiNet Conference: Brain-Machine Interface - Medical Engineering based on Neuroscience, Feb. 5-7, 2020, Osaka , Japan (2020). -
• Ruther P, Ayub S, Klein E, Sharma K, Paul O
  MEMS tools based on integrated light sources for optogenetics
  2020 beim Physikalisches Kolloquium, Institut für Physik, Universität Chemnitz
  
   
  Download file as PDF
• Stieglitz T
  Advanced Testing for future active implants.
  2020 Themenforum “Additive Medicine 4.0, Advanced Testing & Big Data” am Fraunhofer ITEM, 22.01.2020, Hannover (2020).
• Negassi M.,, Parupalli U.,, Suarez-Ibarrola R.,, Schmitt A.,, Hein S.,, Miernik A.,, Reiterer A.
  3D-Reconstruction and Semantic Segmentation of Cystoscopic Images
  2020 MICAD2020; Oxford, UK
  
   
  Download file
• Ruther P, Ayub S, Klein E, Sharma K, Paul O
  Optical MEMS tools based on light-emitting diodes for optogenetics
  2020 Max Planck Institute for Biological Cybernetics, Max-Planck-Ring 8, D-72076 Tübingen
• Fabian Kuhn
  Faster Deterministic Distributed Coloring Through Recursive List Coloring
  2020 31st ACM-SIAM Symp. on Discrete Algorithms (SODA)
  » show abstract« hide abstract
  Abstract

  We provide novel deterministic distributed vertex coloring algorithms. As our main result, we give a deterministic distributed algorithm to compute a (Δ + 1)-coloring of an n-node graph with maximum degree rounds. For graphs with arboricity a, we obtain a deterministic distributed algorithm to compute a (2 + o(1))a-coloring in time . Further, for graphs with bounded neighborhood independence, we show that a (Δ + 1)-coloring can be computed more efficiently in time . This in particular implies that also a (2Δ – 1)-edge coloring can be computed deterministically in rounds, which improves the best known time bound for small values of Δ. All results even hold for the list coloring variants of the problems. As a consequence, we also obtain an improved deterministic n-round algorithm for Δ-coloring non-complete graphs with maximum degree Δ ≥ 3. Most of our algorithms only require messages of O(log n) bits (including the (Δ + 1)-vertex coloring algorithms). Our main technical contribution is a recursive deterministic distributed list coloring algorithm to solve list coloring problems with lists of size Δ1+o(1). Given some list coloring problem and an orientation of the edges, we show how to recursively divide the global color space into smaller subspaces, assign one of the subspaces to each node of the graph, and compute a new edge orientation such that for each node, the list size to out-degree ratio degrades at most by a constant factor on each recursion level.
  
  
   
  Download file as PDF
• John Augustine, Kristian Hinnenthal, Fabian Kuhn, Christian Scheideler, Philipp Schneider
  Shortest Paths in a Hybrid Network Model
  2020 31st ACM-SIAM Symp. on Discrete Algorithms (SODA)
  » show abstract« hide abstract
  Abstract

  We introduce a communication model for hybrid networks, where nodes have access to two different communication modes: a local mode where (like in traditional networks) communication is only possible between specific pairs of nodes, and a global mode where (like in overlay networks) communication between any pair of nodes is possible. Typically, communication over short-range connections is cheaper and can be done at a much higher rate than communication via the overlay network. Therefore, we are focusing on the LOCAL model for the local connections where nodes can exchange an unbounded amount of information per round. For the global communication we assume the so-called nodecapacitated clique model, where in each round every node can exchange O(log n)-bit messages with O(log n) arbitrary nodes. We explore the impact of hybrid communication on the complexity of distributed algorithms by studying the problem of computing shortest paths in the graph given by the local connections. We present the following results. For the all-pairs shortest paths problem, we show that an exact solution can be computed in time Õ (n2/3), and that approximate solutions can be computed in time but not faster. For the single-source shortest paths problem an exact solution can be computed in time , where SPD denotes the shortest path diameter. Furthermore, a (l + o(1))-approximate solution can be computed in time . Finally, we show that for every constant ε > 0, it is possible to compute an O(1)-approximate solution in time.
  
  
   
  Download file as PDF
• L Nitzsche, J Goldschmidt, J Kießling, S Wolf, F Kühnemann, J Wöllenstein
  A Mid-Infrared Dual-Comb Spectrometer for High Sensitivity Multi-Component Trace Gas Detection
  2020 Frontiers in Optics, Washington, DC, United States, 14–17 September; Verlag: Optical Society of America, page: FW7B. 2
  » show abstract« hide abstract
  Abstract

  A dual-comb spectrometer with flexibility in spectral coverage, resolution and central wavelength where all affect sensitivity is optimized to simultaneously determine atmospheric concentration levels of CO 2 and N 2 O from spectra taken at 4470 nm.
• A. Brunauer, B. Breiner, S. Hennig, D. Kainz, R. Verboket, B. Johannsen, D. Baumgartner, K. Mitsakakis, L. Gutzweiler, Z. Shu, P. Koltay, T. Hutzenlaub, N. Paust, R. Zengerle, F. von Stetten, S. M. Früh
  Actuation principles for bioanalytical platforms to combat infectious diseases
  2020 Virtual EMBL Conference: Microfluidics: Designing the Next Wave of Biological Inquiry 2020, 13.-15.07.2020
• Murmann B, Verhelst M, Manoli Y
  Analog-to-Information Conversion
  In: NANO-CHIPS 2030 - On-Chip AI for an Efficient Data-Driven World
  2020, Springer, pages: 275 - 292, ISBN: 978-3-030-18338-7
• Benjamin Völker, Marc Pfeifer, Philipp M Scholl, Bernd Becker
  Annoticity: A Smart Annotation Tool and Data Browser for Electricity Datasets
  2020 5th International Workshop on Non-Intrusive Load Monitoring ACM
  » show abstract« hide abstract
  Abstract

  The growing request for eco-feedback and smart living concepts accelerated the development of Non-Intrusive Load Monitoring (NILM) algorithms during the last decade. Comparing and evaluating these algorithms still remains challenging due to the absence of a common benchmark datasets, and missing best practises for their application. Despite the fact that multiple datasets were recorded for the purpose of comparing NILM algorithms, many researchers still have to record their own dataset in order to meet the requirements of their specific application. Adding ground truth labels to these datasets is a cumbersome and time consuming process as it requires an expert to visually inspect all the data manually. Therefore, we propose the Annoticity inspection and labeling tool which simplifies the process of visualizing and labeling of electricity data. We use an event detector based on the log likelihood ratio test which achieved an F1 score of 90.07% in our experiments. Preliminary results indicate that the effort of generating event labels is reduced by 80.35% using our tool.
  
  
   
  Download file
• Kohler F, Wilde J
  Assembly Technologies for Piezoelectric Sensors up to 1000 °C
  2020 IEEE 70th Electronic Components and Technology Conference (ECTC), Orlando, FL
• Post Regina, Niewelt Tim, Kwapil Wolfram, Schubert Martin C.
  Assessment of Influencing Factors on Lifetime-Based Defect Analysis
  2020 37th EU PVSEC , pages: 332 - 335
  » show abstract« hide abstract
  Abstract

  Since most detection methods are not sensitive enough to detect and characterize recombination active defects in silicon lifetime spectroscopy is an important method in silicon photovoltaics. It is a powerful tool, that can determine the defect parameters Et and k via the analysis of defect parameter solution surfaces. But despite being a crucial method there is no convention for the assessment of uncertainties. This work lines out a possible way to characterize the uncertainty of the method by a simulation of statistical noise onto lifetime curves following the Shockley-Read-Hall-statistics. The uncertainty analysis is done for one exemplary set of defect parameters. It outlines how prone to wrongful parametrization this method can be, if not conducted with great care. Thereby the suggested approach can act as a tool to decrease the uncertainty of the method by understanding, which influences are most crucial to control.
• J. F. Hess, M. Kotrová, S. Calabrese, T. Hutzenlaub, R. Zengerle, M. Brüggemann, N. Paust
  Automated library preparation for next generation sequencing of immunoglobulin gene rearrangements by centrifugal microfluidics
  2020 MicroTAS 2020, 04.-09.10.2020, virtual
• Eberle R., Fell A., Schindler F., Schubert M.C.
  Breakdown of Temperature Sensitivity of Silicon Solar Cells by Simulation Input Parameters
  2020 SiliconPV
• Farahani H, Wagiran R, Urban G
  Capacitive Properties of Ceramic Humidity Sensors Made from Porous Perovskite Films
  2020 IEEE SENSORS 2020
  » show abstract« hide abstract
  Abstract

  In this research, ceramic-based capacitive humidity sensors based on the barium strontium titanate perovskite nanocomposite and doped with the various concentrations of magnesia nanoparticles were fabricated and investigated. The particle size of the sensing elements is varied from 56 nm to 35 nm per dopant surcharges. The interaction between bulk perovskites (pellet) and water vapor was studied by impedance spectroscopy. Presence of the ionic transport even at low RH values is observed from the bulk frequency-capacitance spectra. The EIS results of the bulk sample confirm that the proton transfer operates only by charge transfer kinetics and not diffusion process to metals (up to 90% RH). Among all the proposed sensors, the device contains of 3 mol% magnesia exhibits the most capacitance change (21 pF – 25200 pF) with the sensitivity of 335 pF/RH% in the range of 20–95% RH, and a maximum hysteresis of 5.2% RH at 60% RH. The impact of rest of dopant values on the main perovskite is negative.
• F. Schlenker, E. Kipf, N. Borst, T. Hutzenlaub, N. Paust, R. Zengerle, F. von Stetten, P. Juelg
  Centrifugal microfluidic 4 Plex digital droplet PCR for quantification of circulating tumor DNA
  2020 MicroTAS 2020, 04.-09.10.2020, virtual
• F. Lombeck, F. Hegge, M. von Holst, C. Klose, S. Vierrath, M. Breitwieser
  Ceramic Nanofibers: A versatile material class to improve Electrochemical Energy Applications
  2020 71st International Society of Electrochemistry, Belgrad, Serbia (Online), 30.08. – 04.09.2020
• Hampson K, Cui J, Wincott M, Lane R, Hussain S, Banerjee K, Rajaeipour P, Zappe H, Ataman C, Booth M
  Closed-loop multiconjugate adaptive optics for microscopy
  2020 Adaptive Optics and Wavefront Control for Biological Systems VI
• Subbiah N, Schiffmacher A, Song X, Wilde J
  Comparison of Silver Sintered Assemblies on Non-DCB Substrates
  2020 CIPS 2020; 11th International Conference on Integrated Power Electronics Systems, Berlin, Germany, pp. 1-7.
  
   
  Download file
• Weber T, Zgierski-Johnston C, Klein E, Ayub S, Paul O, Kohl P, Ruther P
  Concentric MEMS-based Opto-electro-mechanical Pacer for Multimodal Cardiac Tissue Excitation
  2020 2020 IEEE 33rd International Conference on Micro Electro Mechanical Systems (MEMS), Vancouver, Canada
  » show abstract« hide abstract
  Abstract

  This paper reports on the fabrication, assembly, characterization and validation of a novel opto-electrical cardiac stimulator designed to augment a mechanical pacing device. The integration of miniaturized electrodes and blue light-emitting diode (LED) chips on the pacer tip with a diameter of 1 mm enables the application of multimodal stimuli in one location on the surface of isolated murine hearts. The opto-electrical stimulator is based on two separate polyimide (PI) substrates each with a thickness of 10 μm combined into a functional unit based on dedicated assembly and encapsulation processes using silicone rubber. The experimental validation in isolated, whole hearts compares electrical, optical and mechanical stimuli exerted at frequencies of up to 8 Hz on Langen-dorff-perfused hearts expressing channelrhodopsin-2. The integrated iridium oxide electrodes implemented above the LED chips enable simultaneous electrical recordings of local cardiac electrical activity.
• M. Liebmann, A. Treffer, M. Bock, U. Wallrabe, R. Grunwald
  Controlling the spectral rotation of ultra-short vortex pulses
  2020 SPIE OPTO 2020, San Francisco, CA, USA , volume: 112970W
• Uwe Wagschal, Thomas Metz, Thomas Waldvogel, Bernd Becker, Linus Feiten, Samuel Weishaupt
  Das »Debat-O-Meter« als neues Tool in der E-Partizipation
  In: Demokratie im 21. Jahrhundert
  2020, Nomos, pages: 341 - 368, ISBN: 978-3-7489-2150-9
• Schiffmacher A, Qelibari A, Rudzki R, Osterwald F, Wilde J
  Deformation Measurements during Active Operation of Power Modules with Novel Assembly and Packaging Technology
  2020 CIPS 2020; 11th International Conference on Integrated Power Electronics Systems, Berlin, Germany
  
   
  Download file
• Universität Freiburg, Technische Fakultät
  Dissertation "Influence of realistic operation conditions on silicon solar cells and energy yield"
  Eberle R.
• Luderer C., Tutsch L., Messmer M., Bivour M., Hermle M.
  Doping Variation at the TCO/a-Si(p) Hole Contact
  In: 37th EU PVSEC
  2020, Proceedings of the 37th European Photovoltaic Solar Energy Conference and Exhibition, page: 493–496,
  » show abstract« hide abstract
  Abstract

  Resistive losses arise at the transport barriers at the interfaces between the different semiconductor materials in the TCO/a-Si/c-Si stack and limit the power output of silicon heterojunction (SHJ) solar cells. A key element is the unisotype recombination junction at the TCO/a-Si(p) interface. We identify sufficient doping on both sides of this junction to be crucial for low contact resistance ( c). For a-Si this is achieved by using a sufficient but not too high doping gas concentration during deposition. On the TCO side high oxygen (O2) gas concentrations during deposition have to be avoided. To combine high transparency of O2-rich TCOs with low c and Rsheet of O2-poor TCOs, we utilize a TCO layer stack. We show that a low O2 content in the vicinity of the TCO/a-Si(p) interface is mandatory to provide efficient tunnelling transport and to avoid resistive losses at the TCO/a-Si(p) interface.
• Luderer, C., Tutsch, L., Messmer, M., Bivour, M., Hermle, M.
  Doping Variation at the TCO/a-Si(p) Hole Contact
  2020 37th EU PVSEC , pages: 493 - 496
  » show abstract« hide abstract
  Abstract

  Resistive losses arise at the transport barriers at the interfaces between the different semiconductor materials in the TCO/a-Si/c-Si stack and limit the power output of silicon heterojunction (SHJ) solar cells. A key element is the unisotype recombination junction at the TCO/a-Si(p) interface. We identify sufficient doping on both sides of this junction to be crucial for low contact resistance ( c). For a-Si this is achieved by using a sufficient but not too high doping gas concentration during deposition. On the TCO side high oxygen (O2) gas concentrations during deposition have to be avoided. To combine high transparency of O2-rich TCOs with low c and Rsheet of O2-poor TCOs, we utilize a TCO layer stack. We show that a low O2 content in the vicinity of the TCO/a-Si(p) interface is mandatory to provide efficient tunnelling transport and to avoid resistive losses at the TCO/a-Si(p) interface.
• Minet Y, Breunig I, Buse K
  Electro-optic based adiabatic frequency conversion in a non-centrosymmetric microresonator
  2020 Laser Resonators, Microresonators, and Beam Control XXII, San Francisco, CA, United States Proceedings of SPIE, volume: 11266, page: 1126606
  » show abstract« hide abstract
  Abstract

  A rather unknown method to perform optical frequency tuning is the adiabatic frequency conversion. But this method has some appealing advantages compared to conventional frequency conversion schemes, i. e. nonlinear- optical based ones: The internal conversion efficiency can reach unity even on a single-photon level. No threshold and no phase-matching conditions need to be fulfilled. Previous realizations of adiabatic frequency conversion suffer from short photon lifetimes, limited tuning range and challenging experimental setups. Here, we employ the Pockels effect for adiabatic frequency conversion (AFC) in a non-centrosymmetric ultrahigh-Q microresonator made out of lithium niobate. With a 70-μm-thick resonator we observe frequency shifts of more than 5 GHz by applying a moderate voltage of 20V. In contrast to former schemes our setup is considerably simplified and provides a linear electric-to-optical link that enables us to generate also arbitrary waveforms of frequency shifts. Furthermore, our presented conversion scheme is well-suited for on-chip fabrication. Volume fabrication and application of larger electric fields for reasonable voltages become possible. By doing this, it is feasible to achieve tuning on the order of hundreds of GHz.
• M. Trotter, N. Borst, R. Thewes, F. von Stetten
  Electrochemical DNA sensing – Principles, commercial systems, and applications
  2020 Biosens Bioelectron, volume: 154, page: 112069
  » show abstract« hide abstract
  Abstract

  Driven by the vision of robust and portable, yet sensitive DNA detection systems for point-of-need applications, the development of electrochemical DNA sensing principles has been of high interest. Many different principles have been developed and these are regularly reviewed. However, the maturity of electrochemical principles and their ability to produce competitive real-world applications is rarely assessed. In this review, general electrochemical DNA sensing principles are briefly introduced and categorized into heterogeneous vs. homogeneous approaches, and then the subcategories label-free vs. labeled and reagent-less vs. reagent-dependent principles. We then focus on reviewing the electrochemical sensing principles implemented in DNA detection systems, which are commercially available or close to market entry, considering the complete analysis process, automation and the field of application. This allows us to outline and discuss which principles have proved suitable for which kinds of applications, as well as the stage of integration and automation. Examples from all the identified categories of electrochemical DNA sensing principles have found application in commercial detection systems or advanced prototypes. Various applications have already been demonstrated, ranging from on-site skin care testing, to food safety to the most frequent in vitro diagnostic tests, partially conducted in automated sample-to-answer devices. Our review is intended to enable researchers in areas related to electrochemistry, biochemistry or microfluidics to assess the commercial state of the art of electrochemical nucleic acid testing, and the interdisciplinary challenges for further improvements.
• Hehn T, Bleitner A, Goeppert J, Hoffmann D, Schillinger D, Sanchez D, Manoli Y
  Energy-Harvesting Applications and Efficient Power Processing
  In: NANO-CHIPS 2030 - On-Chip AI for an Efficient Data-Driven World
  2020, Springer, pages: 405 - 442, ISBN: 978-3-030-18338-7
• Becker, Denise;, Stemmler, Simon;, Reiterer, Alexander
  Entwicklung und Evaluierung eines kompakten Multisensorsystems für den Einsatz auf Drohnen
  In: Ingenieurvermessung 20 Beiträge zum 19. Internationalen Ingenieurvermessungskurs München, 2020
  2020, Wichmann, Thomas A. Wunderlich, pages: 99 - 108, Thomas A. Wunderlich, ISBN: 978-3-87907-672-7
• Benjamin Völker, Marc Pfeifer, Philipp M Scholl, Bernd Becker
  FIRED: A Fully-labeled hIgh-fRequency Electricity Disaggregation Dataset
  2020 The 7th ACM International Conference on Systems for Energy-Efficient Buildings, Cities, and Transportation Virtual Event Japan November, 2020 ACM
  » show abstract« hide abstract
  Abstract

  As more and more homes are equipped with smart electricity meters, home owners gain the ability to monitor their total electricity consumption on a daily or hourly basis. Techniques such as load forecasting, load disaggregation, and activity recognition try to provide even better insights into our electricity consumption, highlight saving potential or improve our daily living. To develop and evaluate these techniques, publicly available datasets are used. We identified a lack of high frequency fully labeled electricity datasets in the residential domain and present the FIRED dataset. It contains 52 of 8kHz aggregated current and voltage readings of the 3-phase supply of a typical residential apartment in Germany. The dataset also contains synchronized ground truth data as 2kHz readings of 21 individual appliances, as well as room temperature readings and fully labeled state changes of the lighting system, resulting in a complete and versatile residential electricity dataset.
• A Eberhardt, C Weber, L Bauersfeld, J Wöllenstein
  FT-IR Coupled Goniometer Setup for Characterization of the Spatial and Spectral Emission of IR-Sources
  2020 SMSI Sensors and Instrumentation (did not take place because of Covid-19 virus pandemic) Chapter: C4.5; AMA, pages: 177 - 178
  » show abstract« hide abstract
  Abstract

  We present a FT-IR coupled goniometer setup, which allows the simultaneous spatial and spectral characterization of optical components used in non-dispersive infrared gas sensor systems. The per-formance of the laboratory setup is demonstrated by comparing reflector and Fresnel lens equipped thermal infrared radiation sources. We show that even the simplest binary Fresnel lenses, when opti-mally designed, can achieve a thinner emission angle than parabolic mirrors at comparable radiation intensities.
• K. Tröndle, A. Itani, F. Koch, R. Zengerle, S. Zimmermann, P. Koltay
  Fabrication and fluidic integration of self-assembled cellular microtubules for nephron-on-chip applications
  2020 MicroTAS 2020, 04.-09.10.2020, virtual
• Szabados J, Breunig I, Buse K
  Frequency comb generation in non-centrosymmetric optical microresonators
  2020 Laser Resonators, Microresonators, and Beam Control XXII, San Francisco, CA, United States Proceedings of SPIE, volume: 11266, page: 112660G
  » show abstract« hide abstract
  Abstract

  Optical frequency combs are a key technology for precision measurements. In the past years, microresonatorbased frequency combs based on third-order χ (3) (Kerr) nonlinearities have attracted significant attention thanks to their small footprint and their wide-ranging applications in fields such as telecommunications, molecular spectroscopy or ultrafast distance measurements. In this contribution, we present a frequency comb generated in a microresonator made of 5% MgO-doped congruent lithium niobate, a non-centrosymmetric crystalline material, employing the generally much stronger second-order χ (2)-nonlinearities of such a material via a scheme of cascaded nonlinear processes. This approach paves the way towards reduced pump thresholds for comb generation and comes with intrinsic suitability for self-referencing.
• H. Nguyen, P. A. Heizmann, F. Lombeck, A. Belletti, B. Britton, S. Vierrath, M. Breitwieser
  Improving the Performance of All-Hydrocarbon PEM Fuel Cells Based on Pemion™ Ionomer
  2020 71st International Society of Electrochemistry, Belgrad, Serbia (Online), 30.08. – 04.09.2020
• R Bernhardsgrütter, C Hepp, M Jägle, H Pernau, K Schmitt, J Wöllenstein
  Inline Quality Monitoring of Diesel Exhaust Fluid (AdBlue) by Using the 3w-Method
  2020 SMSI Sensors and Instrumentation (did not take place because of Covid-19 virus pandemic) Chapter: A5.2; AMA, pages: 79 - 80
  » show abstract« hide abstract
  Abstract

  Quality monitoring of diesel exhaust fluid is crucial for optimal selective catalytic reduction in diesel combustion processes. This article presents a platinum thin film sensor using the 3ω-method to char-acterize the diesel exhaust fluid. The results show that this sensor can determine the urea content with in 1% by weight. An inline measurement is well applicable because the same structure can be used for both concentration and flow measurement.
• A. Brunauer, H. Ceren Ates, C. Dincer, S. M. Früh
  Integrated paper-based sensing devices for diagnostic applications
  In: Comprehensive Analytical Chemistry
  2020, Elsevier,
  » show abstract« hide abstract
  Abstract

  Paper-based sensing platforms are one of the most powerful tools for point-of-care diagnostics. The ease of use while ensuring low production costs of such devices is the key for paper-based technologies to find their way to a successful commercialization. Thus, all steps in the analytical process chain from sample interface, sample preparation, signal amplification to signal transduction and data analysis have to be integrated in a single diagnostic platform. In this chapter, we provide a comprehensive and critical overview on recent developments towards integrated paper-based platforms in academia and industry. Herein, innovative solutions are discussed with respect to their sampling methods such as invasive and non-invasive approaches. We also address the requirements and challenges for the sampling and analysis of the different body fluids. Finally, we present our views about the future perspectives, challenges, and opportunities of the integrated paper-based devices.
• Breunig I, Buse K
  Juggling with light: powerful second-order nonlinear optical effects in whispering gallery resonators
  2020 Laser Resonators, Microresonators, and Beam Control XXII, San Francisco, CA, United States Proceedings of SPIE, volume: 11266, page: 1126609
  » show abstract« hide abstract
  Abstract

  Whispering gallery resonators made out of crystalline materials exhibiting second-order nonlinearities enable frequency mixing such as optical parametric oscillation with high efficiency at low optical input powers and are ideally suited to realize versatile and compact optical frequency converters. Recent achievements stimulate this field further: Frequency conversion not only at a single wavelength or with few wavelengths is possible, entire frequency combs can be transferred into different spectral domains, e.g., allowing the realization of frequency combs in spectral regions that are suitable for multicomponent analytics like the mid-infrared region. Furthermore, these resonators are also supposed to be the ideal host for cascaded nonlinearities allowing the build-up of frequency combs based on second-order nonlinearities. All this comes with new and better schemes to tune whispering gallery resonators, providing advanced opportunities to modulate the laser wavelengths with nanosecond speed employing the Pockels effect. Juggling with light: We will summarize in the presentation these recent achievements, demonstrating that in the field of whispering gallery resonators still many discoveries are ahead of us.
• Kwapil W., Dalke J., Niewelt T., Schubert M.
  LeTID- and (Extended) BO-Related Degradation and Regeneration in B- and Ga-Doped Monocrystalline Silicon during Dark and Illuminated Anneals
  In: 37th EU PVSEC
  2020, , page: 152–155,
  » show abstract« hide abstract
  Abstract

  We study the degradation effects of boron-oxygen related light-induced degradation (LID) and light- and elevated temperature-induced degradation (LeTID) on both B- and Ga-doped Cz-Si wafers from the same industrial producer. The wafers of the two doping types were subjected to the same sample processing and degradation conditions. The studied conditions include dark anneal (DA) at 175°C and illuminated anneals at 75°C and either 1 or 0.1 sun eq. illumination intensity, which allow a good direct comparison of the influence of the dopant elements on the degradation effects. We find an atypical injection dependence of LeTID in the Ga-doped samples compared to the “standard” behavior in B-doped silicon. The Ga-doped samples degrade strongly only when the carrier injection is low. Degradation of Ga-doped samples during DA is only observed on long timescales, resulting in an injection-dependent lifetime dissimilar to LeTID-degraded Ga-doped samples and B-doped samples after both DA and LeTID. The results indicate that the dopants have a strong influence on the degradation behavior.
• Kwapil W., Dalke J., Niewelt T., Schubert M.
  LeTID- and (Extended) BO-Related Degradation and Regeneration in B- and Ga-Doped Monocrystalline Silicon during Dark and Illuminated Anneals
  In: 37th EU PVSEC
  2020, , page: 152–155,
  » show abstract« hide abstract
  Abstract

  We study the degradation effects of boron-oxygen related light-induced degradation (LID) and light- and elevated temperature-induced degradation (LeTID) on both B- and Ga-doped Cz-Si wafers from the same industrial producer. The wafers of the two doping types were subjected to the same sample processing and degradation conditions. The studied conditions include dark anneal (DA) at 175°C and illuminated anneals at 75°C and either 1 or 0.1 sun eq. illumination intensity, which allow a good direct comparison of the influence of the dopant elements on the degradation effects. We find an atypical injection dependence of LeTID in the Ga-doped samples compared to the “standard” behavior in B-doped silicon. The Ga-doped samples degrade strongly only when the carrier injection is low. Degradation of Ga-doped samples during DA is only observed on long timescales, resulting in an injection-dependent lifetime dissimilar to LeTID-degraded Ga-doped samples and B-doped samples after both DA and LeTID. The results indicate that the dopants have a strong influence on the degradation behavior.
• Kwapil W., Dalke J., Niewelt T., Schubert M.
  LeTID- and (Extended) BO-Related Degradation and Regeneration in B- and Ga-Doped Monocrystalline Silicon during Dark and Illuminated Anneals
  In: 37th EU PVSEC
  2020, , page: 152–155,
  » show abstract« hide abstract
  Abstract

  We study the degradation effects of boron-oxygen related light-induced degradation (LID) and light- and elevated temperature-induced degradation (LeTID) on both B- and Ga-doped Cz-Si wafers from the same industrial producer. The wafers of the two doping types were subjected to the same sample processing and degradation conditions. The studied conditions include dark anneal (DA) at 175°C and illuminated anneals at 75°C and either 1 or 0.1 sun eq. illumination intensity, which allow a good direct comparison of the influence of the dopant elements on the degradation effects. We find an atypical injection dependence of LeTID in the Ga-doped samples compared to the “standard” behavior in B-doped silicon. The Ga-doped samples degrade strongly only when the carrier injection is low. Degradation of Ga-doped samples during DA is only observed on long timescales, resulting in an injection-dependent lifetime dissimilar to LeTID-degraded Ga-doped samples and B-doped samples after both DA and LeTID. The results indicate that the dopants have a strong influence on the degradation behavior.
• Kwapil W, Niewelt T, Schubert M, Dalke, J
  LeTID- and (Extended) BO-Related Degradation and Regeneration in B- and Ga-Doped Monocrystalline Silicon during Dark and Illuminated Anneals
  In: 37th EU PVSEC
  2020, Dalke et al., page: 152–155,
  » show abstract« hide abstract
  Abstract

  We study the degradation effects of boron-oxygen related light-induced degradation (LID) and light- and elevated temperature-induced degradation (LeTID) on both B- and Ga-doped Cz-Si wafers from the same industrial producer. The wafers of the two doping types were subjected to the same sample processing and degradation conditions. The studied conditions include dark anneal (DA) at 175°C and illuminated anneals at 75°C and either 1 or 0.1 sun eq. illumination intensity, which allow a good direct comparison of the influence of the dopant elements on the degradation effects. We find an atypical injection dependence of LeTID in the Ga-doped samples compared to the “standard” behavior in B-doped silicon. The Ga-doped samples degrade strongly only when the carrier injection is low. Degradation of Ga-doped samples during DA is only observed on long timescales, resulting in an injection-dependent lifetime dissimilar to LeTID-degraded Ga-doped samples and B-doped samples after both DA and LeTID. The results indicate that the dopants have a strong influence on the degradation behavior.
• Kwapil W., Dalke J., Niewelt T., Schubert M.
  LeTID- and (Extended) BO-Related Degradation and Regeneration in B- and Ga-Doped Monocrystalline Silicon during Dark and Illuminated Anneals
  In: 37th EU PVSEC
  2020, , page: 152–155,
  » show abstract« hide abstract
  Abstract

  We study the degradation effects of boron-oxygen related light-induced degradation (LID) and light- and elevated temperature-induced degradation (LeTID) on both B- and Ga-doped Cz-Si wafers from the same industrial producer. The wafers of the two doping types were subjected to the same sample processing and degradation conditions. The studied conditions include dark anneal (DA) at 175°C and illuminated anneals at 75°C and either 1 or 0.1 sun eq. illumination intensity, which allow a good direct comparison of the influence of the dopant elements on the degradation effects. We find an atypical injection dependence of LeTID in the Ga-doped samples compared to the “standard” behavior in B-doped silicon. The Ga-doped samples degrade strongly only when the carrier injection is low. Degradation of Ga-doped samples during DA is only observed on long timescales, resulting in an injection-dependent lifetime dissimilar to LeTID-degraded Ga-doped samples and B-doped samples after both DA and LeTID. The results indicate that the dopants have a strong influence on the degradation behavior.
• J. F. Hess, T.A. Kohl, M. Kotrová, K. Roensch, T. Paprotka, V. Mohr, T. Hutzenlaub, M. Brüggemann, R. Zengerle, S. Niemann, N. Paust
  Library preparation for next generation sequencing: A review of automation strategies
  2020 Biotechnol Adv, page: 107537
  » show abstract« hide abstract
  Abstract

  Next generation sequencing is in the process of evolving from a technology used for research purposes to one which is applied in clinical diagnostics. Recently introduced high throughput and benchtop instruments offer fully automated sequencing runs at a lower cost per base and faster assay times. In turn, the complex and cumbersome library preparation, starting with isolated nucleic acids and resulting in amplified and barcoded DNA with sequencing adapters, has been identified as a significant bottleneck. Library preparation protocols usually consist of a multistep process and require costly reagents and substantial hands-on-time. Considerable emphasis will need to be placed on standardisation to ensure robustness and reproducibility. This review presents an overview of the current state of automation of library preparation for next generation sequencing. Major challenges associated with library preparation are outlined and different automation strategies are classified according to their functional principle. Pipetting workstations allow high-throughput processing yet offer limited flexibility, whereas microfluidic solutions offer great potential due to miniaturisation and decreased investment costs. For the emerging field of single cell transcriptomics for example, microfluidics enable singularisation of tens of thousands of cells in nanolitre droplets and barcoding of the RNA to assign each nucleic acid sequence to its cell of origin. Finally, two applications, the characterisation of bacterial pathogens and the sequencing within human immunogenetics, are outlined and benefits of automation are discussed.
• Gaiser P., Klingler M, Wilde J
  Lifetime model for the fatigue fracture in Cu/Al2O3/Cu composites: experimental validation of a substantial lifetime enhancement by Cu step etching
  2020 Journal of Electronic Packaging
• Hafner J, Moazenzadeh A, Heinen F, Rodriguez M, Wallrabe U, Paul O
  Long-range telemetric smart orthodontic bracket with CMOS-integrated 3D wirebonder-fabricated microcoils
  2020 IEEE 33rd International Conference on Micro Electro Mechanical Systems (MEMS), Vancouver, Canada , pages: 1266 - 1269
  » show abstract« hide abstract
  Abstract

  This paper reports a novel telemetric smart bracket (TSB) for in vivo force/moment measurements during clinical orthodontic applications. The prototype implements a novel microcoil design resulting in a significant increase of the transmission distance compared to the previous state-of-the-art TSB. Using an automatic wirebonder, the microcoil is wound around an SU-8 post attached to the CMOS sensor wafer. For the first time, thus, 3D wirebonder-fabricated microcoils were integrated on a CMOS substrate, without compromising CMOS functionality. The augmented CMOS system serves here as a force/moment measurement device with six-degree-of-freedom (fx, fy, fz, mx, my, mz) functionality. The achieved transmission distance, i.e. coil-to-coil distance, was thereby increased by 80% compared to the best previous design to 5 mm, without the need for the system to exceed the severe size constraints of 2×2.8×1 mm 3 defined by the bracket dimensions. The increased transmission distance allows uncritical contactless system powering and readout.
• F. Schlenker, E. Kipf, M. Deuter, I. Hoeffkes, N. Borst, T. Hutzenlaub, R. Zengerle, F. von Stetten, N. von Bubnoff, P. Juelg
  Low optimization effort for highly sensitive assays for point mutation quantification in CTDNA: the Mediator Probe digital PCR
  2020 Liquid Biopsy Symposium, 30.10.2020, virtuell
• P Nitzsche, C Dinc, J Wöllenstein, K Schmitt
  Measurement of 13C and 18O Ratio in CO2 using Quantum Cascade Laser based Tunable Absorption Spectroscopy
  2020 SMSI Sensors and Instrumentation (did not take place because of Covid-19 virus pandemic) Chapter: C4; AMA, pages: 175 - 176
  » show abstract« hide abstract
  Abstract

  We present a spectroscopic approach for measurements of 13C and 18O isotopic ratio in carbon dioxide (CO2) gas using a quantum cascade laser (QCL). A narrow linewidth mid-infrared QCL is continuously scanned across three absorption lines of CO2 near 2310 cm-1 including 12C16O2, 13C16O2 and 16O12C18O isotopes. The simultaneous detection of three spectral lines permits the determination of simple concentration ratios (R13 and R18) in atmospheric CO2. With an averaging time of about 10 s both R13 and R18 reach a precision of 0.2‰ and 0.1‰, respectively.
• González G, Stein P, Kretschmer S, Bauer C, Sandic D, Ataman C, Zappe H
  Micro-structured glass probe for endoscopic Optical Coherence Tomography
  2020 SPIE Photonics Europe, 2020, France , volume: 11359
• P. Koch, O. Barth, M. Meyer, R. Streller, R. Zengerle, M. Rombach, M. Jehle
  Microthermoforming: Enhancing blister technology to introduce microstructures in functional packaging
  2020 12. European Thermoforming Conference, Geneva, Switzerland, 18.-20.03.2020
• C Weber, E El-Safoury, C Pannek, L Engel, A Eberhardt, M Bauersfeld, J Wöllenstein
  Multispectral Readout System for Detecting Tiny Color Changes of Gas Sensitive Colorimetric Dyes
  2020 SMSI (did not take place because of Covid-19 virus pandemic) ECS - The Electrochemical Society, pages: 205 - 206
  » show abstract« hide abstract
  Abstract

  The detection of flammable gases is necessary to avoid explosive atmospheres. For this reason, low-cost pellistors are frequently used sensors, although they suffer from high operation temperatures and high power consumption. Within the scope of our work, we present a novel wireless low-power catalytic gas sensor system for flammable gases. The combination of a MEMS-based sensor and low power radio system provide the opportunity to monitor complex infrastructures without using the grid for power supply.
• M. Breitwieser, S. Vierrath
  One for all or one for each application? Recent advances in membrane & ionomer development for electrochemical energy converters
  2020 E3C Electrochemical Cell Concepts Colloquium Fraunhofer UMSICHT, 14.05.2020
• Folwill Y, Zappe H
  Optics and Photonics for Advanced Dimensional Metrology
  2020 Photonics Europe, 2020, France SPIE Digital Library, volume: 11352U
• Tobias Paxian, Bernd Becker
  Pacose: an iterative SAT-based MaxSAT solver
  2020 MaxSAT Evaluation 2020: Solver and Benchmark Descriptions, volume: 16, pages: 12 - 12
• Brunauer A, Ates H, Dincer C, Früh S
  Paper Based Sensors, Volume 89
  In: Integrated paper-based sensing devices for diagnostic applications
  2020, Elsevier B.V., pages: 1 - 54, ISBN: 9780444643452
  » show abstract« hide abstract
  Abstract

  Paper-based sensing platforms are one of the most powerful tools for point-of-care diagnostics. The ease of use while ensuring low production costs of such devices is the key for paper-based technologies to find their way to a successful commercialization. Thus, all steps in the analytical process chain from sample interface, sample preparation, signal amplification to signal transduction and data analysis have to be integrated in a single diagnostic platform. In this chapter, we provide a comprehensive and critical overview on recent developments towards integrated paper-based platforms in academia and industry. Herein, innovative solutions are discussed with respect to their sampling methods such as invasive and non-invasive approaches. We also address the requirements and challenges for the sampling and analysis of the different body fluids. Finally, we present our views about the future perspectives, challenges, and opportunities of the integrated paper-based devices.
• Pascal Raiola, Tobias Paxian, Bernd Becker
  Partial (un-) weighted MaxSAT benchmarks: minimizing witnesses for security weaknesses in reconfigurable scan networks
  2020 MaxSAT Evaluation 2020, volume: 14, pages: 44 - 44
• E. Cruz Ortiz, F. Hegge, M. Breitwieser, S. Vierrath
  Performance Improvement of PEM Water Electrolyzer Anodes via a Bi-Functional Binder Polymer Blends for Ionic and Electrical Conduction
  2020 71st International Society of Electrochemistry, Belgrad, Serbia (Online), 30.08. – 04.09.2020
• S Wolf, T Trendle, N Catalan, J Kießling, J Wöllenstein, F Kühnemann
  Photothermal Common-Path Interferometry for Trace Gas Detection
  2020 Laser Applications to Chemical, Security and Environmental Analysis, DC, United States, 22-26 June; Verlag: Optical Society of America, page: LTu3C.3
  » show abstract« hide abstract
  Abstract

  Photothemal common-path interferometty is used for sensitive infrared gas spectroscopy. Numerical modeling of the effect is validated by experimental results. The method enables compact sensor systems that operate largely independent of the achral excitation wavelength.
• Schäfer M, Tranberg B, Greiner M
  Power flows in complex renewable energy networks
  In: Discoveries at the Frontiers of Science
  2020, Springer, pages: 239 - 251,
• M. Rombach, S. Hin, M. Specht, B. Johannsen, J. Lüddecke, N. Paust, R. Zengerle, K. Mitsakakis
  RespiDisk: A Point-of-Care platform for fully automated detection of respiratory tract infection pathogens in clinical samples
  2020 MicroTAS 2020, 04.-09.10.2020, virtual
• Tobias Paxian, Mael Gay, Devanshi Upadhyaya, Bernd Becker, Ilia Polian
  SAT Benchmarks of AutoFault Attacking AES, LED and PRESENT
  2020 SAT COMPETITION 2020, volume: 20, pages: 79 - 79
• Behrmann O, Bachmann I, Hufert F, Dame G
  Schnellnachweis von SARS-CoV-2 mit recombinase polymerase amplification
  BIOSpektrum, 2020
• Heimsath A, Sutardhio C, Schöttl P, Nitz P
  Soiling of Solar Mirrors - Impact of Incidence Angles on CSP Plant Performance
  2020 25th Solar Power And Chemical Energy Systems International Symposium SolarPACES 2019 25th Solar Power And Chemical Energy Systems International Symposium SolarPACES, volume: 1
• Christoph Scholl, Alexander Konrad
  Symbolic Computer Algebra and SAT Based Information Forwarding for Fully Automatic Divider Verification
  2020 Design Automation Conf., pages: 1 - 6
  » show abstract« hide abstract
  Abstract

  During the last few years Symbolic Computer Algebra (SCA) delivered excellent results in the verification of large integer and finite field multipliers at the gate level. In contrast to those encouraging advances, SCA-based divider verification has been still in its infancy and awaited a major breakthrough. In this paper we analyze the fundamental reasons that prevented the success for SCA-based divider verification so far and present SAT Based Information Forwarding (SBIF). SBIF enhances SCA-based backward rewriting by information propagation in the opposite direction. We successfully apply the method to the fully automatic formal verification of large non-restoring dividers.
• O Yurchenko, H-F Pernau, L Engel, B Bierer, M Jägle, J Wöllenstein
  Systematic Investigations on the Reaction Potential of Catalytic Sensor Materials
  2020 SMSI (did not take place because of Covid-19 virus pandemic) ECS - The Electrochemical Society, pages: 201 - 202
  » show abstract« hide abstract
  Abstract

  We present Simultaneous Thermal Analysis (STA) as a systematic approach for investigation of cata-lytic activity at ideal conditions and for thermal stability. The investigations were performed on different cobalt oxide samples differing in particle size, which is a promising catalyst for methane oxidation. The obtained results demonstrate the reliability of the method for preselection of catalysts for their applica-tion in catalytic gas sensors.
• Schiffmacher A, C. Kempiak, J. Rudzki, F. Osterwald, A. Lindemann, Wilde J.
  Thermomechanical Deformations of Power Modules with Sintered Metal Buffer Layers under Consideration of the Operating Time and Conditions
  2020 IEEE 70th Electronic Components and Technology Conference (ECTC), Orlando, FL, USA, 2020, pp. 561-567
  
   
  Download file
• Alireza Mahzoon, Daniel Große, Christoph Scholl, Rolf Drechsler
  Towards Formal Verification of Optimized and Industrial Multipliers
  2020 Conference on Design, Automation and Test in Europe (DATE), pages: 544 - 549
  » show abstract« hide abstract
  Abstract

  Formal verification methods have made huge progress over the last decades. However, proving the correctness of arithmetic circuits involving integer multipliers still drives the verification techniques to their limits. Recently, Symbolic Computer Algebra (SCA) methods have shown good results in the verification of both large and non-trivial multipliers. Their success is mainly based on (1) reverse engineering and identifying basic building blocks, (2) finding converging gate cones which start from the basic building blocks and (3) early removal of redundant terms (vanishing monomials) to avoid the blow-up during backward rewriting. Despite these important accomplishments, verifying optimized and technology-mapped multipliers is an almost unexplored area. This creates major barriers for industrial use as most of the designs are area and delay optimized. To overcome the barriers, we propose a novel SCA-method which supports the formal verification of a large variety of optimized multipliers. Our method takes advantage of a dynamic substitution ordering to avoid the monomial explosion during backward rewriting. Experimental results confirm the efficiency of our approach in the verification of a wide range of optimized multipliers including industrial benchmarks.
• S. Koch, C. Klose, B. Britton, M. Breitwieser, S. Vierrath
  Towards stable catalyst layers for water electrolysis based on anion-exchange membranes
  2020 71st International Society of Electrochemistry, Belgrad, Serbia (Online), 30.08. – 04.09.2020
• Breunig I, Herr S, Buse K
  Tunable single-frequency lasing in whispering gallery resonators
  2020 Laser Resonators, Microresonators, and Beam Control XXII, San Francisco, CA, United States Proceedings of SPIE, volume: 11266, page: 112660Q
  » show abstract« hide abstract
  Abstract

  Whispering gallery resonators (WGRs) are ideally suited for the realization of miniaturized lasers. Due to their high quality factor and small mode volume, they allow for low-threshold and narrow-linewidth emission from (sub)millimeter-sized cavities made of laser-active materials. However, so far the majority of experimental realizations relies on expensive pump light sources like narrow-linewidth or pulsed laser systems, impeding most applications. We demonstrate two whispering-gallery-based single-frequency lasers pumped by compact spectrally multimode low-cost laser diodes. The spheroidally-shaped millemeter-sized WGRs are made of Pr:LiLuF4 and Nd:YVO4. They provide quality factors beyond 107 at the lasing wavelengths (640 nm and 1064 nm, respectively). The pump light is focused onto the rim of the WGR. We observe single frequency emission at milliwatt output powers. The temporal stability of the output power and of the output frequency are determined to be ±1:5 % and ±30 MHz within 30 min, respectively. By changing the temperature of the cavity, we achieve mode-hop-free tuning exceeding 11 GHz.
• L Nitzsche, J Kießling, S Wolf, F Kühnemann, J Wöllenstein
  Ultra-fast gas spectroscopy with a dual-comb spectrometer
  2020 SMSI Sensors and Instrumentation (did not take place because of Covid-19 virus pandemic) Chapter: B4.4; AMA, pages: 123 - 124
  » show abstract« hide abstract
  Abstract

  Dual-comb spectroscopy has the potential to measure broadband transmission spectra fast and precisely. To employ these features for gas analysis we present a fiber-based dual-comb-spectrometer and compare the spectrum of an HCN filled cell with a simulation using the HITRAN database. Although point-to-point fluctuations across the spectrum show a rms of 4% fit results indicate that absorptions features with (α* L)= 0.01 can be detected within measurement time of 0.5 ms.
• Reiterer, Alexander, Störk, Dominik, Wäschle, Katharina, Leydecker, Achim
  Vollautomatisierte Auswertung von Mobile-Mapping-Daten mithilfe von Machine Learning
  In: Ingenieurvermessung 20 Beiträge zum 19. Internationalen Ingenieurvermessungskurs München, 2020
  2020, Wichmann, Thomas A. Wunderlich, pages: 141 - 147, Thomas A. Wunderlich, ISBN: 978-3-87907-672-7
• B Bierer, J Wöllenstein, O Yurchenko, L Engel, H Pernau, L Reindl, D Grgic
  Wireless low-power warning system for the detection of flammable gases
  2020 SMSI Sensors and Instrumentation (did not take place because of Covid-19 virus pandemic) Chapter: B4.3; AMA, pages: 121 - 122
  » show abstract« hide abstract
  Abstract

  The detection of flammable gases is necessary to avoid explosive atmospheres. For this reason, low-cost pellistors are frequently used sensors, although they suffer from high operation temperatures and high power consumption. Within the scope of our work, we present a novel wireless low-power catalytic gas sensor system for flammable gases. The combination of a MEMS-based sensor and low power radio system provide the opportunity to monitor complex infrastructures without using the grid for power supply.
• Schiffmacher A, Strahringer D, Kempiak C, Rudzki J, Osterwald F, Lindemann A, Wilde J
  Zuverlässigkeitsuntersuchungen von Leistungsmodulen mit neuartiger Aufbau- und Verbindungstechnik
  2020 49. Kolloquium Leistungshalbleiter-Bauelemente und ihre systemtechnische Integration
• B. Johannsen
  id Diagnosis of Respiratory Tract Infections Using a Point-of-Care Platform Incorporating a Clinical Decision Support Algorithm
  2020 pHealth2020, 14. – 16. 09. 2020