@misc{ReiterSenguelMaietal., author = {Reiter, Sebastian and Seng{\"u}l, Akant and Mai, Christian and Spirito, Davide and Wenger, Christian and Fischer, Inga Anita}, title = {On-chip refractive index sensors based on plasmonic TiN Nanohole Arrays}, series = {2024 IEEE Silicon Photonics Conference (SiPhotonics)}, journal = {2024 IEEE Silicon Photonics Conference (SiPhotonics)}, isbn = {979-8-3503-9404-7}, issn = {1949-209X}, doi = {10.1109/SiPhotonics60897.2024.10544048}, pages = {2}, language = {de} } @misc{JoseMaiWengeretal., author = {Jose, Josmy and Mai, Christian and Wenger, Christian and Fischer, Inga Anita}, title = {Integration concept of plasmonic TiN nanohole arrays in a 200 mm BiCMOS Si technology for refractive index sensor applications}, series = {iCCC2024 - iCampµs Cottbus Conference}, journal = {iCCC2024 - iCampµs Cottbus Conference}, doi = {10.5162/iCCC2024/7.2}, pages = {96 -- 99}, language = {de} } @misc{MaiPeczekKrohetal., author = {Mai, Christian and Peczek, Anna and Kroh, Aleksandra and Jose, Josmy and Reiter, Sebastian and Wenger, Christian and Fischer, Inga Anita}, title = {Towards a CMOS compatible refractive index sensor: cointegration of TiN nanohole arrays and Ge photodetectors in a 200 mm wafer silicon technology}, series = {Optics Express}, volume = {32}, journal = {Optics Express}, number = {17}, publisher = {Optica Publishing Group}, issn = {1094-4087}, doi = {10.1364/OE.530081}, pages = {29099 -- 29111}, abstract = {In this work, we present the monolithic integration of a TiN nanohole array and a Ge photodetector towards a CMOS compatible fabrication of a refractive index sensor in a 200 mm wafer silicon technology. We developed a technology process that enables fabrication with high yields of around 90\%. Ge photodetectors with a Ge layer thickness of 450 nm and an area of 1600 µm2 (40 µm x 40 µm) show dark current densities of around 129 mA/cm2 and responsivities of 0.114 A/W measured by top illumination (TE polarization; λ = 1310 nm; angle of incidence = 14 °) at a reverse bias of 1 V. Nanohole arrays were structured in a 150 nm thick TiN layer. They were integrated into the back end of line and placed spatially close to the Ge photodetectors. After the metallization, passivation, and pad opening, the nanohole arrays were released with the help of an amorphous silicon stop layer. A significant impact of the TiN nanohole arrays on the optical behavior of the photodetector could be proven on the wafer level. Photocurrent measurements by top illumination confirm a strong dependence of optical properties on the polarization of the incident light and the nanohole array design. We demonstrate very stable photocurrents on the wafer level with a standard deviation of σ \< 6\%.}, language = {en} } @misc{DerschRoemerPerezetal., author = {Dersch, Nadine and Roemer, Christian and Perez, Eduardo and Wenger, Christian and Schwarz, Mike and I{\~n}{\´i}guez, Benjam{\´i}n and Kloes, Alexander}, title = {Fast circuit simulation of memristive crossbar arrays with bimodal stochastic synaptic weights}, series = {2024 IEEE Latin American Electron Devices Conference (LAEDC)}, journal = {2024 IEEE Latin American Electron Devices Conference (LAEDC)}, publisher = {IEEE}, isbn = {979-8-3503-6130-8}, issn = {979-8-3503-6129-2}, doi = {10.1109/LAEDC61552.2024.10555829}, pages = {1 -- 4}, abstract = {This paper presents an approach for highly efficient circuit simulation of hardware-based artificial neural networks by using memristive crossbar array architectures. There are already possibilities to test neural networks with stochastic weights via simulations like the macro model NeuroSim. However, the noise-based variability approach offers more realistic setting options including elements of a classical circuit simulation for more precise analysis of neural networks. With this approach, statistical parameter fluctuations can be simulated based on different distribution functions of devices. In Cadence Virtuoso, a simulation of a crossbar array with 10 synaptic weights following a bimodal distribution, the new approach shows a 1,000x speedup compared to a Monte Carlo simulation. Initial tests of a memristive crossbar array with over 15,000 stochastic weights to classify the MNIST dataset show that the new approach can be used to test the functionality of hardware-based neural networks.}, language = {en} } @misc{ReiterHanMaietal., author = {Reiter, Sebastian and Han, Weijia and Mai, Christian and Spirito, Davide and Jose, Josmy and Z{\"o}llner, Marvin Hartwig and Fursenko, Oksana and Schubert, Markus Andreas and Stemmler, Ivo and Wenger, Christian and Fischer, Inga Anita}, title = {Titanium Nitride Plasmonic Nanohole Arrays for CMOS-compatible integrated refractive index sensing: influence of layer thickness on optical properties}, series = {Plasmonics}, journal = {Plasmonics}, issn = {1557-1963}, doi = {10.1007/s11468-023-01810-3}, pages = {1 -- 13}, language = {en} } @misc{HanReiterSchlipfetal., author = {Han, Weijia and Reiter, Sebastian and Schlipf, Jon and Mai, Christian and Spirito, Davide and Jose, Josmy and Wenger, Christian and Fischer, Inga Anita}, title = {Strongly enhanced sensitivities of CMOS compatible plasmonic titanium nitride nanohole arrays for refractive index sensing under oblique incidence}, series = {Optics Express}, volume = {31}, journal = {Optics Express}, number = {11}, issn = {1094-4087}, doi = {10.1364/OE.481993}, pages = {17389 -- 17407}, abstract = {Titanium nitride (TiN) is a complementary metal-oxide-semiconductor (CMOS) compatible material with large potential for the fabrication of plasmonic structures suited for device integration. However, the comparatively large optical losses can be detrimental for application. This work reports a CMOS compatible TiN nanohole array (NHA) on top of a multilayer stack for potential use in integrated refractive index sensing with high sensitivities at wavelengths between 800 and 1500 nm. The stack, consisting of the TiN NHA on a silicon dioxide (SiO2) layer with Si as substrate (TiN NHA/SiO2/Si), is prepared using an industrial CMOS compatible process. The TiN NHA/SiO2/Si shows Fano resonances in reflectance spectra under oblique excitation, which are well reproduced by simulation using both finite difference time domain (FDTD) and rigorous coupled-wave analysis (RCWA) methods. The sensitivities derived from spectroscopic characterizations increase with the increasing incident angle and match well with the simulated sensitivities. Our systematic simulation-based investigation of the sensitivity of the TiN NHA/SiO2/Si stack under varied conditions reveals that very large sensitivities up to 2305 nm per refractive index unit (nm RIU-1) are predicted when the refractive index of superstrate is similar to that of the SiO2 layer. We analyze in detail how the interplay between plasmonic and photonic resonances such as surface plasmon polaritons (SPPs), localized surface plasmon resonances (LSPRs), Rayleigh Anomalies (RAs), and photonic microcavity modes (Fabry-P{\´e}rot resonances) contributes to this result. This work not only reveals the tunability of TiN nanostructures for plasmonic applications but also paves the way to explore efficient devices for sensing in broad conditions.}, language = {en} } @misc{ZoellnerAdrianoWiethegeretal., author = {Z{\"o}llner, Christian and Adriano, Christian M. and Wietheger, Simon and Lambers, Leen and Giese, Holger}, title = {Tool support for the teaching of state-based behavior modeling}, series = {MODELS '22: Proceedings of the 25th International Conference on Model Driven Engineering Languages and Systems: Companion Proceedings}, journal = {MODELS '22: Proceedings of the 25th International Conference on Model Driven Engineering Languages and Systems: Companion Proceedings}, editor = {K{\"u}hn, Thomas and Sousa, Vasco}, publisher = {Association for Computing Machinery}, address = {New York, NY, United States}, isbn = {978-1-4503-9467-3}, doi = {10.1145/3550356.3556501}, pages = {87 -- 94}, abstract = {Modeling tools are commonly adopted in classrooms. However, complex state-based behavioral models still pose a challenge for students to understand and validate, mostly because of the intricate semantics of these models. We investigated this challenge and developed dedicated tool support in the form of a validation framework based on the YAKINDU Statechart Tools. Our validation framework simulates environments that interact with the code generated from statecharts as a means to animate various open-ended scenarios and predefined test cases that challenge the students' models. This enables short and user-friendly feedback cycles, which lowers the barrier for students to learn state-based behavioral models. We designed the validation framework to be extensible and made it available as an open source project together with two example environments and complete teaching materials. We report on our experiences in two undergraduate modeling courses (approx. 100 students each). Our results are promising in the sense that we detected positive effects of tool adoption and a surprising lack thereof, which we discuss w.r.t. lessons learned and future work.}, language = {en} } @book{SteffensDawoudRechenaueretal., author = {Steffens, Oliver and Dawoud, Belal and Rechenauer, Christian and M{\"u}hlberger, Thomas and Trauner, Matthias and Saller, Tobias and Riederer, Michael and Haug, Sonja and Vetter, Miriam and Cerullo, Laura and Weber, Karsten and Draeger, Susan and Kominis, Lena and Steininger, Peter and Malz, Sebastian and Gerdes, Thorsten and Melzl, Johannes and Haas, Katharina and Helling, Dominik and Zielbauer, Lukas and Stelzl, Andr{\´e} and Andratschke, Christin and Grießhammer, Peter and Giebisch, Matthias and Preis, Michael and Michlbauer, David and Walbrunn, Johannes and Nagel, Klaus and Lang, Christian and Schnabl, Andreas and Toutouly, Lovis and R{\"u}ckerl, Alexander}, title = {MAGGIE - Energetische Modernisierung des genossenschaftlichen Wohnquartiers Margaretenau in Regensburg : Musterl{\"o}sungen f{\"u}r solaroptimiertes Wohnen mit innovativen solaraktiven Baustoffen und einem KI-gest{\"u}tzten Energiemanagement f{\"u}r eine netzdienliche, emissionsarme Strom- und W{\"a}rmelogistik; Ergebnisbericht}, editor = {Steffens, Oliver}, address = {Regensburg}, doi = {10.35096/othr/pub-5901}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-59011}, pages = {XVIII, 462}, abstract = {Das Projekt MAGGIE ist ein vom Bundesministerium f{\"u}r Wirtschaft und Klimaschutz (BMWK) gef{\"o}rdertes Projekt innerhalb der F{\"o}rderinitiative „Solares Bauen/Energieeziente Stadt" im Rahmen des 6. Energieforschungsprogramms. Im Projekt MAGGIE sollten beispielhaft f{\"u}r das genossenschaftliche historische Stadtquartier „Margaretenau" in Regensburg Musterl{\"o}sungen f{\"u}r energieoptimiertes Wohnen mit innovativen Wandauauten aus solaraktiven Baustoen und einer vorhersagebasierten Versorgungstechnologie entwickelt werden. F{\"u}r ein bestehendes Wohngeb{\"a}ude als Demonstrationsund Versuchsobjekt wurde beispielhaft ein neuartiges, besonders ezientes Hybridsystem aus W{\"a}rmepumpentechnologie und Kraft-W{\"a}rme-Kopplung (Blockheizkraftwerk) konzipiert und umgesetzt. F{\"u}r die denkmalgerechte Modernisierung historischer Fassaden wurde ein solaraktives und solaradaptives Außenputzsystem entwickelt und getestet. Der erh{\"o}hte Ausnutzungsgrad solarer Gewinne in Verbindung mit einer verbesserten thermischen Behaglichkeit im Geb{\"a}udeinnerendurch innovative Innenputz-/Innenfarbsysteme kann maßgeblich zur Einsparung von Heizw{\"a}rme beitragen. Dazu wurden mit Blick auf die bauphysikalischen und w{\"a}rmetechnischen Eigenschaften Versuche an einem eigens aufgebauten Wandpr{\"u}fstand durchgef{\"u}hrt, erg{\"a}nzt durch bauphysikalische Modellsimulationen. Die Ergebnisse sind vielversprechend, auch wenn eine serientaugliche L{\"o}sung f{\"u}r den Einsatz am Geb{\"a}ude im Rahmen des Projektes nicht entstehen konnte. Das wichtigste Ziel des Projektes war es, ein hochezientes, skalierbares Versorgungssystem durch die Kombination von Kraft-W{\"a}rme-Kopplung (Blockheizkraftwerk, BHKW) mit einer Pvunterst{\"u}tzten W{\"a}rmepumpen-Technologie zu entwickeln und im Detail zu modellieren, in Verbindung mit einer innovativenW{\"a}rmelogistik zur Reduktion der Verteilungsverluste f{\"u}r dieWarm-wasserversorgung. Das Systemsollte neben einem hohen Eigenstrom-Nutzungsanteil auch netzdienliche Schwarmfunktionalit{\"a}t aufweisen. Die Skalierbarkeit des vernetzten Systems („Mitwachsen") erlaubt eine abschnittsweise Modernisierung des gesamten Ensembles {\"u}ber mehrere Jahre, was f{\"u}r die Finanzierbarkeit und praktische Umsetzung erhebliche Bedeutung hat. Durch die hohe Energieezienz wird die Warmmiete f{\"u}r die Bewohner der genossenschaftlichen Siedlung durch die Modernisierungsmaßnahmen nicht erh{\"o}ht, so dass auch nach der Modernisierung ein bezahlbares Wohnen sichergestellt wird. Die Auslegung des Systems erfolgte durch ein neu entwickeltes, generisch einsetzbares Planungs-, Optimierungs- und Steuerungstool, das auch die Regelung im Betrieb {\"u}bernimmt. Die in Echtzeit laufende Nachoptimierung des Systems w{\"a}hrend des Betriebs greift auf reale Monitoringdaten zu. Die Einbindung von Nutzerbedarfsprolen, Stromb{\"o}rse und Wetterdaten in die Steuerung ist vorbereitet und gestattet einen dynamischen und perspektivischen Anlagenbetrieb zur Maximierung der Solar- und Umweltw{\"a}rme-Anteile der Energieversorgung. Mithilfe einer intensiven Nutzerinformation in einem partizipativen Planungsprozess wurde die Akzeptanz der experimentellen Maßnahmen sichergestellt. Durch oene Kommunikation der Zielsetzungen und L{\"o}sungsans{\"a}tze f{\"u}r eine klimafreundliche, kostenbewusste Restaurierung des Wohnungsbestands und die aktive Einbindung der Bewohner fand das Projekt das Interesse und die Unterst{\"u}tzung der Menschen, auch in der schwierigen Phase der Umsetzung baulicher Maßnahmen in einem zwangsl{\"a}ug in Abschnitten vor{\"u}bergehend entmieteten Geb{\"a}ude.}, language = {de} } @misc{DerschPerezBoschQuesadaPerezetal., author = {Dersch, Nadine and Perez-Bosch Quesada, Emilio and P{\´e}rez, Eduardo and Wenger, Christian and Roemer, Christian and Schwarz, Mike and Kloes, Alexander}, title = {Efficient circuit simulation of a memristive crossbar array with synaptic weight variability}, series = {Solid State Electronics}, volume = {209}, journal = {Solid State Electronics}, issn = {0038-1101}, doi = {10.1016/j.sse.2023.108760}, abstract = {In this paper, we present a method for highly-efficient circuit simulation of a hardware-based artificial neural network realized in a memristive crossbar array. The statistical variability of the devices is considered by a noise-based simulation technique. For the simulation of a crossbar array with 8 synaptic weights in Cadence Virtuoso the new approach shows a more than 200x speed improvement compared to a Monte Carlo approach, yielding the same results. In addition, first results of an ANN with more than 15,000 memristive devices classifying test data of the MNIST dataset are shown, for which the speed improvement is expected to be several orders of magnitude. Furthermore, the influence on the classification of parasitic resistances of the connection lines in the crossbar is shown.}, language = {en} } @misc{KleinNadolskiZenkeretal., author = {Klein, Rupert and Nadolski, Maikel and Zenker, Christian and Oevermann, Michael and Paschereit, Christian Oliver}, title = {Pressure gain combustion for gas turbines : analysis of a fully coupled engine model}, series = {Journal of Engineering for Gas Turbines and Power}, volume = {147}, journal = {Journal of Engineering for Gas Turbines and Power}, number = {2}, publisher = {ASME International}, issn = {0742-4795}, doi = {10.1115/1.4066348}, pages = {26}, abstract = {The "Shockless Explosion Combustion" (SEC) concept for gas turbine combustors, introduced in 2014, approximates constant volume combustion (CVC) by harnessing acoustic confinement of auto-igniting gas packets. The resulting pressure waves simultaneously transmit combustion energy to a turbine plenum and facilitate the combustor's recharging against an average pressure gain. Challenges in actualizing an SEC-driven gas turbine include (i) the creation of charge stratifications for nearly homogeneous auto-ignition, (ii) protecting the turbocomponents from combustion-induced pressure fluctuations, (iii) providing evidence that efficiency gains comparable to those of CVC over deflagrative combustion can be realized, and (iv) designing an effective one-way intake valve. This work addresses challenges (i)-(iii) utilizing computational engine models incorporating a quasi-one-dimensional combustor, zero- and two-dimensional (2D) compressor and turbine plena, and quasi-stationary turbocomponents. Two SEC operational modes are identified which fire at roughly one and two times the combustors' acoustic frequencies. Results for SEC-driven gas turbines with compressor pressure ratios of 6:1 and 20:1 reveal 1.5-fold mean pressure gains across the combustors. Assuming ideally efficient compressors and turbines, efficiency gains over engines with deflagration-based combustors of 30\% and 18\% are realized, respectively. With absolute values of 52\% and 66\%, the obtained efficiencies are close to the theoretical Humphrey cycle efficiencies of 54\% and 65\% for the mentioned precompression ratios. Detailed thermodynamic cycle analyses for individual gas parcels suggest that there is room for further efficiency gains through optimized plenum and combustor designs.}, language = {en} } @misc{StichLinzWallravenetal., author = {Stich, Timo and Linz, Christian and Wallraven, Christian and Cunningham, Douglas William and Magnor, Marcus}, title = {Perception-motivated interpolation of image sequences}, series = {ACM Transactions and Applied Perception}, volume = {8}, journal = {ACM Transactions and Applied Perception}, number = {2}, issn = {1544-3965}, pages = {1 -- 25}, language = {en} }