@phdthesis{16935, author = {{Moussalem, Diego Campos}}, title = {{{Knowledge Graphs for Multilingual Language Translation and Generation}}}, doi = {{10.17619/UNIPB/1-980}}, year = {{2020}}, } @article{13770, author = {{Karl, Holger and Kundisch, Dennis and Meyer auf der Heide, Friedhelm and Wehrheim, Heike}}, journal = {{Business & Information Systems Engineering}}, number = {{6}}, pages = {{467--481}}, publisher = {{Springer}}, title = {{{A Case for a New IT Ecosystem: On-The-Fly Computing}}}, doi = {{10.1007/s12599-019-00627-x}}, volume = {{62}}, year = {{2020}}, } @article{17598, author = {{Nakatani, Tomohiro and Boeddeker, Christoph and Kinoshita, Keisuke and Ikeshita, Rintaro and Delcroix, Marc and Haeb-Umbach, Reinhold}}, journal = {{IEEE/ACM Transactions on Audio, Speech, and Language Processing}}, pages = {{1--1}}, title = {{{Jointly optimal denoising, dereverberation, and source separation}}}, doi = {{10.1109/TASLP.2020.3013118}}, year = {{2020}}, } @techreport{30034, author = {{Stender, Marius and Wallscheid, Oliver and Böcker, Joachim}}, title = {{{Data Set Description: Three-Phase IGBT Two-Level Inverter for Electrical Drives}}}, doi = {{10.13140/RG.2.2.23335.37280}}, year = {{2020}}, } @article{34789, author = {{Amiri, Habib and Glöckner, Helge and Schmeding, Alexander}}, issn = {{0044-8753}}, journal = {{Archivum Mathematicum}}, keywords = {{22A22, 22E65, 22E67, 46T10, 47H30, 58D15, 58H05}}, number = {{5}}, pages = {{307–356}}, title = {{{Lie groupoids of mappings taking values in a Lie groupoid}}}, doi = {{10.5817/AM2020-5-307}}, volume = {{56}}, year = {{2020}}, } @article{34787, author = {{Glöckner, Helge and Masbough, Niku}}, issn = {{0146-4124}}, journal = {{Topology Proceedings}}, keywords = {{54B10, 54D45, 54D50}}, pages = {{35–38}}, title = {{{Products of regular locally compact spaces are k_R-spaces}}}, volume = {{55}}, year = {{2020}}, } @unpublished{34808, abstract = {{For suitable finite-dimensional smooth manifolds M (possibly with various kinds of boundary or corners), locally convex topological vector spaces F and non-negative integers k, we construct continuous linear operators S_n from the space of F-valued k times continuously differentiable functions on M to the corresponding space of smooth functions such that S_n(f) converges to f in C^k(M,F) as n tends to infinity, uniformly for f in compact subsets of C^k(M,F). We also study the existence of continuous linear right inverses for restriction maps from C^k(M,F) to C^k(L,F) if L is a closed subset of M, endowed with a C^k-manifold structure turning the inclusion map from L to M into a C^k-map. Moreover, we construct continuous linear right inverses for restriction operators between spaces of sections in vector bundles in many situations, and smooth local right inverses for restriction operators between manifolds of mappings. We also obtain smoothing results for sections in fibre bundles.}}, author = {{Glöckner, Helge}}, booktitle = {{arXiv:2006.00254}}, title = {{{Smoothing operators for vector-valued functions and extension operators}}}, year = {{2020}}, } @inproceedings{18390, abstract = {{ Efficiencies and energy yields of microinverters available on the market during 2014‒2020 have been measured, compared, and ranked. Conversion efficiencies as a function of load have been measured indoors with high accuracy and ranked according to Euro- and CEC weightings. Energy yields have been measured outdoors via identical and calibrated crystalline silicon PV modules of 215 Wp each. Inverters with two inputs have been fed by two of those modules. DC input, AC power output and energy yield of each micro-inverter have been recorded by individual calibrated electricity meters. Apparently, some inverters have been optimized for high irradiance levels and ranked better at the CEC efficiency ranking, others performed very well also at low irradiance levels, thus ranking higher at in the EU efficiency ranking. Efficiency ranks are slightly deviating from rankings by energy yield measurements. At one inverter, a slow MPPT algorithm that barely could follow quickly changing irradiance levels is most probably responsible for this effect. Another inverter switched off for a while after operation at high power, another one failed permanently. Apparently, some inverters are been optimized to show excellent datasheet ratings for EU- or CEC- efficiency. On the other hand, two inverters (each featuring two inputs) did not show an outstanding performance at the EU- and CEC-ratings but achieved leading ranks for AC energy yields. For the customer, AC yield is a major performance indicator of a microinverter and should be included in the datasheet.}}, author = {{Krauter, Stefan and Bendfeld, Jörg}}, booktitle = {{Proceedings of the EUPVSEC 2020}}, isbn = {{ 3-936338-73-6}}, location = {{online}}, pages = {{935 -- 938}}, title = {{{Micro-Inverters: An Update of Comparison of Conversion Efficiencies and Energy Yields}}}, doi = {{10.4229/EUPVSEC20202020-4DO.7.2}}, year = {{2020}}, } @inproceedings{16857, author = {{Krauter, Stefan and Bendfeld, Jörg}}, booktitle = {{Tagungsband des 35. Symposiums für Photovoltaische Solarenergie, Kloster Banz, Bad Staffelstein (Deutschland)}}, location = {{Bad Staffelstein}}, title = {{{Einfluss der Betriebstemperatur auf den Wirkungsgrad von Modul-Wechselrichtern für PV-Netzeinspeisungen}}}, year = {{2020}}, } @inproceedings{19393, abstract = {{To provide a simple instrument to operate residential Load-Shifting or Demand-Side-Management systems, the measurement of the actual grid frequency seems to be an appropriate method. Due to the present inflexibility and the lack of sufficient throttling capabilities of lignite and nuclear power plants, a surplus of electricity generation occurs during periods of high wind and solar power generation. While the specific CO2- emission is decreasing then ‒ due to the increased share of Renewables, the grid frequency is increasing (to a certain limit). Using the grid frequency as an indicator to switch-on and off certain loads (loads that do not require power permanently (e.g. dishwashers, washing machines, dryers, fridges and freezers, heaters) could provide a simple, inexpensive demand-side management indicator to lower specific CO2‒emssions and costs (if a dynamic consumption tariff is available). To check the truthfulness of that hypothesis, the grid and frequency data of the German grid of the year 2018 have been collected and a the correlation between grid frequency, power surplus, share of renewables vs. CO2-contents and price at the European energy exchange (EEX) have been calculated. The results show: Correlation between frequency and share of renewables is quite low (r = 0.155) due to the fact that primary grid control quickly compensates deviations from the 50 Hz nominal frequency. There is a good anti-correlation (r = - 0.687) between the EEX‒prices and the share of renewables in the grid. Over the years, correlation between electricity trading prices (EEX) and CO2 emissions is quite good (r =0.665), within the one year (2018) that correlation almost doesn’t exist, possibly due to the inflexibility of the bulky lignite power plants that even operate at negative prices. }}, author = {{Krauter, Stefan and Zhang, L.}}, booktitle = {{Proceedings of the 37th European Photovoltaic Solar Energy Conference, 07 - 11 September 2020.}}, issn = {{ 3-936338-73-6}}, keywords = {{Keywords: Load-Shifting, Demand-Side-Management, DSM, grid frequency, EEX, electricity trading prices, renewable share, flexibility, emissions, CO2}}, location = {{online}}, pages = {{1815 -- 1817}}, title = {{{Triggering Demand‒Side‒Management: Correlation of electricity prices, share of renewables, CO2‒contents, and grid‒frequency in the German electricity grid.}}}, doi = {{10.4229/EUPVSEC20202020-6BV.5.9}}, year = {{2020}}, } @inproceedings{19390, abstract = {{Due to the strong reduction of PV prices, storage plays a dominating role in overall system costs. A steeper elevation angle would result in a more balanced seasonal PV yield, at the cost of PV yield reductions during summer, but allowing reduced storage capacities. Additionally, the effect of a single-axis tracking system has been investigated, generating more electricity during the morning and evening hours, thus reducing daily storage requirements. The necessary PV size and storage capacities required for the German energy supply (1,500 TWh after electrification of all sectors) via 100% renewable energies and a 50% solar share have been calculated via the HOMER Pro software, considering the bridging of periods of "dark lulls“ in winter, using costs of 2030 (Table 1). Results: The increase of module elevation angles above the typical 30° leads to a reduction of investment and supply costs. The optimum is reached at a cost reduction of -1.5% for an elevation angle at the latitude of the installation site. An explanation is that high elevation angles are favorable for clear winter days, but not at all for the critical days with diffuse irradiance only, so the battery capacity must be increased. For the same reason, tracking systems do not offer any cost advantage (at least for the ones without an option for horizontal positioning during diffuse days).}}, author = {{Krauter, Stefan and Rustemovic, D. and Khatibi, Arash}}, booktitle = {{Proceedings of the 37th European Photovoltaic Solar Energy Conference, 07 - 11 September 2020}}, isbn = {{3-936338-73-6}}, keywords = {{Energy Storage, PV system integration, Large Grid-connected PV systems, Simulation, Energy Supply Options}}, location = {{online}}, pages = {{1818 -- 1819}}, title = {{{Reduction of required storage capacities for a 100% renewable energy supply in Germany, if new PV systems are installed with east-west tracking systems at increased elevation angles}}}, doi = {{10.4229/EUPVSEC20202020-6BV.5.10}}, year = {{2020}}, } @inproceedings{18387, abstract = {{ During comparative measurements of different PV microinverters, two yield issues came up that could not be explored via conventional efficiency measurements, but do have a significant impact on electrical energy yield: First category of issues are either sluggish or nervously acting maximum–power–point–tracking devices, which lead to reduced energy yields. The other category of issues is thermal: As a first explanation for observed reduced energy yields, it has been assumed that the conversion efficiency degrades at higher operating temperatures. This matter has been investigated in this article: A change in conversion efficiency could not be observed for elevated operation temperatures up to 50°C, despite high-precision and repeated measurements. But it was found that some inverters temporarily interrupted (or entirely stopped) operation after long periods of running at high temperatures. Also, a reduction in potential maximum power output has been detected for those inverters. Summarizing: With a high degree of certainty it can be stated that those reported yield losses have been caused by the temporary shutdowns and power limitations of the inverters.}}, author = {{Krauter, Stefan and Bendfeld, Jörg}}, booktitle = {{Proceedings of the EU PVSEC 2020 }}, issn = {{3-936338-73-6}}, keywords = {{AC-modules, Microinverter, Power Conditioning, Thermal Performance, Ventilation, Stability, Efficiency, Yield}}, location = {{online}}, pages = {{1179 -- 1180}}, title = {{{Elevated Temperatures Affecting Efficiency, Overall Performance and Energy Yield of PV Microinverters}}}, doi = {{10.4229/EUPVSEC20202020-4AV.3.6}}, year = {{2020}}, } @inproceedings{19383, abstract = {{Due to the present inflexibility and the lack of sufficient throttling capabilities of lignite and nuclear power plants, a surplus of electricity generation occurs during periods of high wind and solar power generation in the German electricity grid. While the specific CO2-emission is decreasing then - due to the increased share of Renewables, the grid frequency should be increasing (to a certain limit). Using the grid frequency as an indicator to switch-on and -off certain loads (loads that do not require power permanently (e.g. dishwashers, washing machines, dryers, fridges and freezers, heaters) could provide a simple, inexpensive demand-side-management indicator to lower specific CO2-emissions and costs (if a dynamic consumption tariff is applied). To check the truthfulness of that hypothesis, the grid and frequency data of the German grid of the year 2018 have been collected and the correlations between grid frequency, share of renewables, CO2-contents, and actual price at the European energy exchange (EEX) have been calculated. The results show: Correlation between grid frequency and the share of renewables is quite low (r=0.155) due to the fact that primary grid control quickly compensates deviations from the 50 Hz nominal frequency. As expected, there is a good anti-correlation (r=-0.687) between the EEX-prices and the share of renewables in the grid. Over the years, correlation between electricity trading prices (EEX) and CO2 emissions is quite good (r=0.665), within the one year (2018) that correlation almost doesn't exist, possibly due to the inflexibility of the bulky lignite baseload power plants that even operate at negative prices.}}, author = {{Krauter, Stefan and Zhang, L.}}, booktitle = {{Proceedings of the 47th IEEE Photovoltaic Specialists Conference (PVSC 47) 2020}}, keywords = {{CO2, EEX, Grid frequency, DSM, electricity price, Renewable share}}, location = {{online}}, pages = {{1672--1674}}, title = {{{Correlation of grid-frequency, electricity prices, share of Renewables and CO2-contents of German electricity grid to enable inexpensive triggering of Demand-Side-Management}}}, doi = {{10.1109/PVSC45281.2020.9300487}}, year = {{2020}}, } @inproceedings{16899, abstract = {{To compare efficiency and yield of many micro-inverters available on the world market in 2014-2020, an in- and outdoor test laboratory at the University of Paderborn has been set up. The inverters have been fed by identical and calibrated crystalline silicon PV modules of 215 Wp. To monitor accurately DC input, AC power output and energy yield, each of the micro-inverters has been equipped with a calibrated electricity meter. For micro-inverters requiring control units for grid-feeding that has been acquired also. The comparison covers efficiency-load characteristics as well as electrical energy yields. Purchase costs vary considerably between the models in comparison, sometimes inverter costs are higher than module costs, particularly if an additional grid-connection or interface device is needed for operation. The weighted conversion efficiency according to EU and CEC standards has been measured and calculated. While some inverters have been optimized for high irradiance levels, they ranked better at the CEC efficiency, others performed very well also for low irradiance levels, thus ranking higher at in the EU-efficiency tables. These results are deviating from the actual energy yield measurements, which show a slightly different ranking. At one inverter, an accurate, but very slow MPPT algorithm that barely could follow quickly changing irradiance levels could be the reason for this effect. Another inverter switched off after operation at high power output for a while. Apparently, some inverters are been optimized to show excellent EU and CEC efficiency ratings. Two of the inverters featuring two inputs did not show an exceptional performance at the EU- and CEC-ratings, but they achieved top ranks at the AC energy yield for the first years. For the customer, the AC yield is a major performance indicator of any microinverter and should be included in the datasheet.}}, author = {{Krauter, Stefan and Bendfeld, Jörg}}, booktitle = {{Proceedings of the 47th IEEE Photovoltaic Specialists Conference (PVSC 47) JUNE 15 - AUGUST 21, 2020 VIRTUAL MEETING}}, issn = {{ 0160-8371}}, keywords = {{yield, AC, micro-inverter, MPPT, CEC rating, EU efficiency, Photovoltaic, Solar}}, location = {{VIRTUAL MEETING}}, pages = {{1429--1432}}, publisher = {{IEEE}}, title = {{{Comparison of Microinverters: Update on Rankings of Conversion Efficiencies and Energy Yields}}}, doi = {{10.1109/PVSC45281.2020.9300953}}, year = {{2020}}, } @inproceedings{16855, author = {{Krauter, Stefan and Zhang, L.}}, booktitle = {{Tagungsband des 35. Symposiums für Photovoltaische Solarenergie, Kloster Banz, Bad Staffelstein (Deutschland)}}, location = {{Bad Staffelstein}}, title = {{{Eignung der Netzfrequenz als Instrument der Entscheidungsfindung zur Auslösung von Lastverschiebungen bei niedrigen spezifischen CO2-Emissionen und EEX-Handelspreisen}}}, year = {{2020}}, } @inproceedings{16858, author = {{Krauter, Stefan and Zhang, L.}}, booktitle = {{Proceedings of the 14th International Renewable Energy Storage Conference, Düsseldorf (Deutschland), 10.–12. März 2020 (verschoben: 16.–18. März 2021)}}, location = {{Düsseldorf (Deutschland)}}, title = {{{Probability of Correct Decision–Making at Triggering of Load-Shifting Intended for low CO2-intensity and low EEX trading-prices via simple Grid Frequency Monitoring}}}, year = {{2020}}, } @inproceedings{29298, abstract = {{Die Themen „Big Data“, „Künstliche Intelligenz und „Data Science“ werden seit einiger Zeit nicht nur in der breiten Öffentlichkeit kontrovers diskutiert, sondern stellen für die Ausbildung in den IT- und IT-nahen Berufen schon heute neue Herausforderungen dar, die in Zukunft durch die gesellschaftliche und technologische Weiterentwicklung hin zu einer Datengesellschaft noch größer werden. An dieser Stelle stellt sich die Frage, welche Aspekte dieses großen Themenkomplexes für Schule und Ausbildung von Wichtigkeit sind und wie diese Themen sinnstiftend und gewinnbringend in die informatische Ausbildung in verschiedenen Bildungsgängen integriert werden können. Im Rahmen des von uns im Jahr 2017 organisierten Symposiums zum Thema „Data Science“ wurden für die Bildung relevante Aspekte erörtert, wodurch als Kernelemente für den Unterricht Algorithmen der Künstlichen Intelligenz und ihre Anwendung in Industrie und Gesellschaft, Explorationen von Big Data sowie der Umgang mit eigenen Daten in sozialen Netzwerken herausgearbeitet wurden. Ziel ist, aus diesen Themenbereichen sowohl ein umfassendes Curriculum als auch Module für verschiedene Unterrichtsszenarien zu entwickeln und zu erproben. Durch diese Materialien soll es Lehrkräften aus der Informatik, Mathematik oder Technik ermöglicht werden, diese Themen auf Basis des Curriculums und der erprobten Unterrichtskonzepte selbst zu unterrichten. Hierfür wurde im Rahmen des Projekts ProDaBi (Projekt Data Science und Big Data in der Schule, https://www.prodabi.de), initiiert von der Telekom Stiftung, ein experimenteller Projektkurs entwickelt, den wir mit Schüler:innen der Sekundarstufe II an der Universität Paderborn im Schuljahr 2018/19 durchführten. Dieser Kurs enthält neben einem Modul zur Exploration von Big Data und einem weiteren Modul zum Maschinellen Lernen als Teil der Künstlichen Intelligenz auch eine Projektphase, die es in Zusammenarbeit mit lokalen Unternehmen den Schüler:innen ermöglicht, das Erlernte in ein reales Data Science-Projekt einzubringen. Aus den Erfahrungen dieses Projektkurses sowie den parallel durchgeführten Erprobungen einzelner Bausteine auch mit beruflichen Schulen werden ab dem Schuljahr 2019/20 die hierfür verwendeten Materialien weiterentwickelt und weiteren Kooperationspartnern zur Erprobung zur Verfügung gestellt. Damit wurden zum Ende des Projekts nicht nur vollständige Unterrichtsmaterialien, sondern auch ein umfassendes Curriculum entwickelt.}}, author = {{Opel, Simone Anna and Schlichtig, Michael}}, booktitle = {{Sammelband der 27. Fachtagung der BAG Berufliche Bildung}}, editor = {{Vollmer, Thomas and Karges, Torben and Richter, Tim and Schlömer, Britta and Schütt-Sayed, Sören}}, keywords = {{Berufsbildung, vocational education, Ausbildung, training, berufliche Weiterbildung, advanced vocational education, Digitalisierung, digitalization, Unterricht, teaching, Lehrmethode, teaching method, Interdisziplinarität, interdisciplinarity, Fachdidaktik, subject didactics, Curriculum, curriculum, gewerblich-technischer Beruf, vocational/technical occupation, Fachkraft, specialist, Qualifikationsanforderungen, qualification requirements, Kompetenz, competence, Lehrerbildung, teacher training, Bundesrepublik Deutschland, Federal Republic of Germany}}, location = {{Siegen}}, pages = {{176--194}}, publisher = {{wbv Media GmbH & Co. KG}}, title = {{{Data Science und Big Data in der beruflichen Bildung – Konzeption und Erprobung eines Projektkurses für die Sekundarstufe II}}}, doi = {{https://doi.org/10.3278/6004722w}}, volume = {{55}}, year = {{2020}}, } @inproceedings{20504, abstract = {{In recent years time domain speech separation has excelled over frequency domain separation in single channel scenarios and noise-free environments. In this paper we dissect the gains of the time-domain audio separation network (TasNet) approach by gradually replacing components of an utterance-level permutation invariant training (u-PIT) based separation system in the frequency domain until the TasNet system is reached, thus blending components of frequency domain approaches with those of time domain approaches. Some of the intermediate variants achieve comparable signal-to-distortion ratio (SDR) gains to TasNet, but retain the advantage of frequency domain processing: compatibility with classic signal processing tools such as frequency-domain beamforming and the human interpretability of the masks. Furthermore, we show that the scale invariant signal-to-distortion ratio (si-SDR) criterion used as loss function in TasNet is related to a logarithmic mean square error criterion and that it is this criterion which contributes most reliable to the performance advantage of TasNet. Finally, we critically assess which gains in a noise-free single channel environment generalize to more realistic reverberant conditions.}}, author = {{Heitkaemper, Jens and Jakobeit, Darius and Boeddeker, Christoph and Drude, Lukas and Haeb-Umbach, Reinhold}}, booktitle = {{ICASSP 2020 Virtual Barcelona Spain}}, keywords = {{voice activity detection, speech activity detection, neural network, statistical speech processing}}, title = {{{Demystifying TasNet: A Dissecting Approach}}}, year = {{2020}}, } @unpublished{28263, abstract = {{Following the success of the 1st, 2nd, 3rd, 4th and 5th CHiME challenges we organize the 6th CHiME Speech Separation and Recognition Challenge (CHiME-6). The new challenge revisits the previous CHiME-5 challenge and further considers the problem of distant multi-microphone conversational speech diarization and recognition in everyday home environments. Speech material is the same as the previous CHiME-5 recordings except for accurate array synchronization. The material was elicited using a dinner party scenario with efforts taken to capture data that is representative of natural conversational speech. This paper provides a baseline description of the CHiME-6 challenge for both segmented multispeaker speech recognition (Track 1) and unsegmented multispeaker speech recognition (Track 2). Of note, Track 2 is the first challenge activity in the community to tackle an unsegmented multispeaker speech recognition scenario with a complete set of reproducible open source baselines providing speech enhancement, speaker diarization, and speech recognition modules.}}, author = {{Watanabe, Shinji and Mandel, Michael and Barker, Jon and Vincent, Emmanuel and Arora, Ashish and Chang, Xuankai and Khudanpur, Sanjeev and Manohar, Vimal and Povey, Daniel and Raj, Desh and Snyder, David and Subramanian, Aswin Shanmugam and Trmal, Jan and Yair, Bar Ben and Boeddeker, Christoph and Ni, Zhaoheng and Fujita, Yusuke and Horiguchi, Shota and Kanda, Naoyuki and Yoshioka, Takuya and Ryant, Neville}}, booktitle = {{arXiv:2004.09249}}, title = {{{CHiME-6 Challenge:Tackling Multispeaker Speech Recognition for Unsegmented Recordings}}}, year = {{2020}}, } @article{29399, author = {{Limebeer, D. J. N. and Ober-Blöbaum, Sina and Farshi, F. H.}}, journal = {{IEEE Transactions on Automatic Control}}, pages = {{1381--1396}}, title = {{{Variational integrators for dissipative systems}}}, volume = {{65(4)}}, year = {{2020}}, }