TY - CHAP A1 - Schubert, Martin J. W. A1 - Lee, Wai-Kong A1 - Ooi, Boon Yaik T1 - Quantization and Sampling Effects in Fast Digitally Controlled Switch-Mode DC/DC Buck Converters T2 - 2021 IEEE Industrial Electronics and Applications Conference (IEACon): 22.11.2021 - 23.11.2021, Penang, Malaysia N2 - Software-defined control of DC/DC switch mode power converters features unequaled flexibility compared to analog control. For fast switching converters as recently used for low power applications, digital control may cause steady-state oscillations known as limit cycles. This effect based on a quantized duty cycle is compared to other aberrations such as output ripple voltage, which is inherent to any pulse-width modulator. A distinction is made between DC and AC errors. The latter are divided into synchronous and asynchronous output voltage disturbances. Synchronous AC errors are composed of the switching frequency and its harmonics. KW - aberrations due to digitization KW - digital pulse-width modulation (DPWM) KW - low power DC/DC buck conversion KW - output voltage sampling Y1 - 2021 SN - 978-1-7281-9253-6 U6 - https://doi.org/10.1109/IEACon51066.2021.9654272 SP - 56 EP - 61 PB - IEEE ER - TY - CHAP A1 - Croce, Valeria A1 - Diamantidis, Dimitris A1 - Sýkora, Miroslav ED - Bien, Jan T1 - Planning post earthquake surveys: assessments and reconstruction of small historical centres T2 - 1st IABSE Online Symposium 2020, Synergy of culture and civil engineering - history and challenges: Wrocław, Poland, 7-9 October 2020, Proceedings N2 - The contribution presents a methodological procedure for the management and planning of interventions after earthquake events in small historic centres. Reference is made to the case study of Castelluccio di Norcia, a village in the Apennine Mountains affected by the seismic sequence that hit Central Italy in 2016. The earthquake risk of the area and the damaging events of 2016 are critically reviewed. The implementation of cognitive analysis and the application of advanced survey techniques involving the use of nmanned Aerial Vehicles (UAVs) for the purposes of emergency management and monitoring of damaged areas are analysed. The outcomes, combined with the direct involvement of the local population, represent a complete and integrated approach allowing the definition of a) possible intervention strategies, b) related decision criteria and c) practical recommendations for the reconstruction and regeneration of Castelluccio, and, in general, of small historic centres damaged by catastrophic events. Y1 - 2021 UR - http://toc.proceedings.com/57946webtoc.pdf SN - 978-1-7138-2387-2 SP - 332 EP - 339 PB - Curran Associates Inc CY - Red Hook, NY ER - TY - CHAP A1 - Hänninen, Risto A1 - Niemetz, Michael A1 - Schoepe, Wilfried T1 - Transition to turbulence in oscillatory superflows T2 - ETC 2013 - 14th European Turbulence Conference 2020: 2 September 2013 - 4 September 2013, Lyon, France N2 - The flow of superfluid helium-4 at very low temperatures around an oscillating microsphere has been studied in detail. At small oscillation amplitudes the drag force is linear in velocity amplitude. Above a critical velocity amplitude vc a transition from potential flow to turbulent flow is signaled by a large and nonlinear drag force that scales as (v2 - v2 c ), where vc is found to be independent of temperature (below 1 K) and of driving force. Interestingly, the critical velocity is found to scale as vc ~ √κω, where κ = h/m ≈ 10−7 m2/s (h is Planck's constant and m is the mass of a helium-4 atom) is the circulation quantum of the superfluid vortices and ω/2π is the oscillation frequency ranging from about 120 Hz to 700 Hz. We also observe slightly above vc that the flow pattern is unstable and switches intermittently between potential flow and turbulence. From time series recorded at constant drive and temperature we have investigated the statistical properties of this switching phenomenon. In this talk the universal law vc ~ √κω will be discussed in detail. It can be derived theoretically in various ways: firstly, from a qualitative but very general argument based on the "superfluid Reynolds number" Rs = vl/κ where v is the flow velocity and l is a characteristic length scale, secondly, and in more detail, from Kopnin's equation of the time dependence of the vortex line density, and, finally, we have obtained this law rigorously by dynamical scaling of the equations of motion of vortex dynamics. Y1 - 2020 UR - http://etc14.ens-lyon.fr/openconf/modules/request.php?module=oc_proceedings&action=view.php&a=Accept&id=17 ER - TY - CHAP A1 - Rieger, Anna A1 - Mühlbauer, Christian A1 - Rabl, Hans-Peter A1 - Weber, Rainer T1 - Dissonanz als Bewertungskriterium multi-tonalen Schalls T2 - Fortschritte der Akustik - DAGA 2020: 46. Deutsche Jahrestagung für Akustik Y1 - 2020 UR - https://www.dega-akustik.de/publikationen/online-proceedings/ SP - 788 EP - 791 PB - Deutsche Gesellschaft für Akustik e.V. ER - TY - CHAP A1 - Mühlbauer, Christian A1 - Rabl, Hans-Peter A1 - Rottengruber, Herrmann ED - Siebenpfeiffer, Wolfgang T1 - Development of a Methodology for Acoustic Analysis and Optimization of Mechatronic Fuel Injection Systems T2 - Automotive Acoustics Conference 2019: Proceedings, 5. Internationale ATZ-Fachtagung Fahrzeugakustik N2 - To identify the sound quality of fuel injection systems as a frontloading measure, a system test bench has been developed that simulates the structure and airborne noise emission. The setup of the system test bench includes an assembly of the acoustical relevant engine parts and an encapsulated drive for the high-pressure pump. A specific control unit enables a high variability for the operation strategy of the injection system. The focus of this study is on the development of a methodology to analyze and optimize the sound quality of gasoline direct injectors in critical operation points by suitable active means. For this, the injection parameters in engine idle have been identified and subsequently transferred to the system test bench. Additionally, the injection parameters have been optimized acoustically and the impacts on the key functions regarding injection rating and shot-to-shot scattering of the injected fuel mass are discussed. Y1 - 2020 SN - 978-3-658-27668-3 U6 - https://doi.org/10.1007/978-3-658-27669-0_15 SP - 211 EP - 225 PB - Springer Vieweg CY - Wiesbaden ER - TY - CHAP A1 - Reindl, Andrea A1 - Meier, Hans A1 - Niemetz, Michael ED - Brinkmann, André ED - Karl, Wolfgang ED - Lankes, Stefan ED - Tomforde, Sven ED - Pionteck, Thilo ED - Trinitis, Carsten T1 - Scalable, Decentralized Battery Management System Based on Self-organizing Nodes T2 - Architecture of computing systems - ARCS 2020: 33rd international conference, Aachen, Germany, May 25-28, 2020, proceedings N2 - Due to the transition to renewable energy sources and the increasing share of electric vehicles and smart grids, batteries are gaining in importance. Battery management systems (BMSs) are required for optimal, reliable operation. In this paper, existing BMS topologies are presented and evaluated in terms of reliability, scalability and flexibility. The decentralisation of BMSs and associated advantages are shown. A scalable, reconfigurable BMS based on a distributed architecture of self-organized, locally controlled nodes is proposed. For distributed system control, producers, batteries and consumers each are equipped with a local microcontroller based control unit, which monitors and controls the local parameters with its own computing and communication resources. Features, advantages and challenges to overcome of the proposed approach are described. KW - Availability Decentralized control KW - Battery management systems KW - Controller Area Network KW - distributed management KW - fault tolerant control KW - Multi-microcomputer system KW - Reconfigurable architectures KW - Renewable energy sources KW - Scalability KW - Topology Y1 - 2020 SN - 978-3-030-52793-8 U6 - https://doi.org/10.1007/978-3-030-52794-5_13 VL - 12155 SP - 171 EP - 184 PB - Springer International Publishing CY - Cham ER - TY - CHAP A1 - Anders, M. A1 - Briem, Ulrich A1 - Novak, G. A1 - Steinbach, G. ED - Katterfeld, André ED - Krause, Friedrich ED - Pfeiffer, Dagmar ED - Richter, Klaus T1 - Neue VDI-Richtlinie für die Seiltriebauslegung T2 - 28. Internationale Kranfachtagung 2020 "Kran 4.0: Potenziale der Digitalisierung", 4. und 5. März 2020, Magdeburg Y1 - 2020 SN - 978-3-947068-08-1 SP - 59 EP - 72 PB - LOGiSCH GmbH CY - Magdeburg ER - TY - CHAP A1 - Diamantidis, Dimitris A1 - Sýkora, Miroslav T1 - Reliability Differentiation and Uniform Risk in Standards BT - a Critical Review and a Practical Appraisal: kriticki pregled i prakticna ocjena T2 - Scientific Symposium Future Trends in Civil Engineering, Zagreb,Croatia, 17 October 2029 N2 - Reliability of structures and infrastructures is a major issue in structural engineering. Structural standards have traditionally been mainly concerned with public safety preventing loss of life or injury; this view has been shifting in recent years towards minimisation of economic loss. This contribution discusses the reliability differentiation principle in modern standards. Its aim is to achieve uniform risk levels for the various classes of structures. Codified criteria for reliability differentiation and risk informed decisions inherent in standards and especially in the Eurocodes are critically reviewed. It is shown that the classification of structures based on consequences of failure is an approach that has not been widely implemented in everyday design. Practical rules for the classification and implementation in design are needed and related proposals are presented. T2 - Razlikovanje pouzdanosti i ujednacenost rizika u propisima Y1 - 2020 U6 - https://doi.org/10.5592/CO/FTCE.2019.11 SP - 241 EP - 260 ER - TY - CHAP A1 - Wagner, Marcus A1 - Al-Abadi, Ali A1 - Buchner, Stefan ED - López-Fernández, Xose M., T1 - A Numerical-Based Model to Determine the Resonance of the Steel Cores of Transformers T2 - ARWtr 2022 proceedings : 2022 7th Advanced Research Workshop on Transformers (ARWtr), October (23)24-26, 2022, Baiona, Spain N2 - The laminated steel core of transformers is one of the main sources of the generated sound, as it is excited by different electromagnetic effects during its normal operation. If the core is excited in its eigenfrequencies, the sound generated by a transformer will increase significantly. Therefore, knowledge of the core’s eigenmodes and -frequencies in an early design stage can decrease expenses by avoiding costly modifications that might be required to avoid the sound levels exceeding the specified values after the final factory acceptance test. The current study focuses on developing a core resonance model to determine the eigenmodes and -frequencies of a transformer core. The core’s geometry was simplified to a connected-beam structure and a numerical-based approach was applied. The accuracy of the developed model was validated against finite element method (FEM), using ANSYS on a reference core model. Y1 - 2022 SN - 978-84-09-45157-9 U6 - https://doi.org/https://doi.org/10.23919/ARWtr54586.2022.9959938 SP - 36 EP - 41 PB - IEEE ER - TY - CHAP A1 - Grab, Robin A1 - Rauch, Johannes A1 - Götz, Rebekka A1 - Brückl, Oliver A1 - Eichner, Stefan A1 - Engel, Bernd T1 - Q-Dynamik: Blindleistungsstellgeschwindigkeiten im Verteilnetz T2 - Zukünftige Stromnetze: 27.-28. Januar 2021, 03.-04. Februar 2021, Tagungsunterlagen N2 - Mit der Energiewende geht eine starke Dezentralisierung der Energieeinspeisung einher. So sind im Deutschland des Jahres 2020 rund 31.000 Windenergieanlagen (WEA) in Betrieb, während bei der Solarenergie vor kurzem die zweimillionste Photovoltaik-Anlage (PVA) installiert wurde. Fast alle diese dezentralen Energieressourcen (DER) sind nach den Einspeiserichtlinien der Vergangenheit und der Gegenwart in der Lage, Blindleistung bereitzustellen, um die Spannung im Netz zu regeln und zum Blindleistungsausgleich beizutragen. Weitere potentielle dezentrale Blindleistungsquellen wie Blockheizkraftwerke, Kompensationsanlagen und perspektivisch sogar Verbraucher und Speicher sind im Verteilnetz zu finden. Durch den stetigen Rückbau konventioneller Großkraftwerke, welche dem Übertragungsnetz bisher als Blindleistungsquellen zur Verfügung standen, bedarf es einer Untersuchung mit der Fragestellung, in welchem Maß die neue Erzeugungslandschaft auch in diesem Feld als Ersatz dienen kann. Ein mögliches Hindernis für einen breitangelegten Einsatz von DER zu Zwecken des spannungsebenenübergreifenden Blindleistungsmanagements ist mangelndes Wissen über die Regeldynamik dieser verteilten Blindleistungsquellen. Übertragungs- und Verteilnetzbetreiber, die DER aktiv für Blindleistungsausgleich oder statische Spannungsregelung einsetzen, geben in der Regel ihre Blindleistungsanforderungen in kleineren Stufen mit erheblichen Latenzzeiten zwischen zwei Schritten weiter. Befürchtet wird, dass schnellere Sprünge in der Blindleistungsvorgabe zu instabilen Betriebszuständen oder anderweitigen Fehlfunktionen im Netz führen können. Eine genauere Kenntnis der dynamischen Fähigkeiten vorhandener Blindleistungsquellen sowie der Auswirkungen auf die Netzstabilität und den Netzschutz könnte dazu beitragen, die Geschwindigkeit der Blindleistungsbereitstellung zu optimieren und somit temporäre Spannungsschwankungen und -verluste zu minimieren und die Spannungsstabilität insgesamt zu verbessern. Durch eine entsprechende Regelungs- und Einsatzstrategie kann ein optimales Zusammenspiel der verschiedenen Technologien zur Deckung der Blindleistungsbedarfe für unterschiedliche Zeitbereiche erzielt werden. Hierfür ist eine genaue Kenntnis der Blindleistungsstellgeschwindigkeiten und des dynamischen Regelverhaltens erforderlich. Dieser Beitrag stellt dazu Ergebnisse aus dem Forschungsprojekt „Q-Integral“ vor. Um die relevanten Zeitkonstanten der Blindleistungsbereitstellung vollständig aufzuführen, werden zunächst typische Kommunikationszeiten für die Übermittlung von Sollwerten diskutiert. Anschließend werden Untersuchungen zu theoretischen und praktischen Reaktionszeiten verschiedener Blindleistungsquellen vorgestellt. Dafür werden verschiedene Technologien wie Umrichter für PVA, Batteriespeicher und WEA sowie Synchrongeneratoren, die bei thermischen Kraftwerken die dominierende Technologie sind, betrachtet. Abschließend werden diese Werte mit realen Blindleistungsstellgeschwindigkeiten von ausgedehnten Wind- und Solarkraftwerken verglichen. KW - Blindleistung KW - Blindleistungsmanagement KW - Q-Dynamik KW - Blindleistungsquellen KW - Verteilungsnetz Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-58762 SN - 978-3-948176-12-9 SP - 46 EP - 55 PB - Conexio-PSE GmbH CY - Pforzheim ER -