@article{FoersterAdamMikulicsetal.2002, author = {F{\"o}rster, Arnold and Adam, R. and Mikulics, M. and Schelten, J.}, title = {Fabrication and subpicosecond optical response of low-temperature-grown GaAs freestanding photoconductive devices. Adam, R.; Mikulics, M.; Forster, A.; Schelten, J.; Siegel, M.; Kordos, P.; Zheng, X.; Wu, S.; Sobolewski, R.}, series = {Applied Physics Letters. 81 (2002), H. 18}, journal = {Applied Physics Letters. 81 (2002), H. 18}, isbn = {1077-3118}, pages = {3485 -- 3487}, year = {2002}, language = {en} } @article{Foerster2003, author = {F{\"o}rster, Arnold}, title = {Layer Deposition I}, series = {Fundamentals of nanoelectronics / Stefan Bl{\"u}gel ... (ed.). - (Lecture manuscripts of the ... Spring School of the Department of Solid State Research ; 34). - (Schriften des Forschungszentrums J{\"u}lich : Materie und Material ; 14 ; 34)}, journal = {Fundamentals of nanoelectronics / Stefan Bl{\"u}gel ... (ed.). - (Lecture manuscripts of the ... Spring School of the Department of Solid State Research ; 34). - (Schriften des Forschungszentrums J{\"u}lich : Materie und Material ; 14 ; 34)}, publisher = {Forschungszentrum, Zentralbibliothek}, address = {J{\"u}lich}, isbn = {3-89336-319-X}, pages = {C2.1 -- C2.13}, year = {2003}, language = {en} } @article{Foerster1994, author = {F{\"o}rster, Arnold}, title = {Resonant tunneling diodes : the effect of structural properties on their performance}, series = {Festk{\"o}rperprobleme = Advances in solid state physics. 33 (1994)}, journal = {Festk{\"o}rperprobleme = Advances in solid state physics. 33 (1994)}, isbn = {0065-3357}, pages = {37 -- 62}, year = {1994}, language = {en} } @article{Foerster2000, author = {F{\"o}rster, Arnold}, title = {Resonant tunneling diodes operating as modern quantum transport devices}, series = {Proceedings of the Tenth International Workshop on the Physics of Semiconductor Devices : (December 14 - 18, 1999) / ed.: Vikram Kumar ... - Vol. 2}, journal = {Proceedings of the Tenth International Workshop on the Physics of Semiconductor Devices : (December 14 - 18, 1999) / ed.: Vikram Kumar ... - Vol. 2}, publisher = {Allied Publ.}, address = {New Delhi [u.a.]}, isbn = {81-7023-998-2}, pages = {966 -- 966}, year = {2000}, language = {en} } @article{Foerster1995, author = {F{\"o}rster, Arnold}, title = {Ultrahigh frequency measurements of magnetic penetration length and surface impedance of YBa2Cu3O7-x microstriplines on Si and GaAs substrates . R{\"u}ders, F; Hollricher, O.; Copetti, C. A. ; F{\"o}rster, A. ; Buchal, Ch. ; Prusseit, W. ; Kinder, H.}, series = {Journal of Applied Physics. 77 (1995), H. 10}, journal = {Journal of Applied Physics. 77 (1995), H. 10}, isbn = {1089-7550}, pages = {5282 -- 5286}, year = {1995}, language = {en} } @article{FuruichiYoshinobuErmelenkoetal.2001, author = {Furuichi, K. and Yoshinobu, T. and Ermelenko, T. and Mourzina, Y. and Iwasaki, H. and Sch{\"o}ning, Michael Josef}, title = {Simultaneous visualization of multiple ions by the chemical imaging sensor}, series = {Proceedings of the 5th East Asian Conference on Chemical Sensors; the 33rd Chemical Sensor Symposium : December 4 - 7, 2001, Huis Ten Bosch, Sasebo-shi, Nagasaki, Japan / Japan Association of Chemical Sensors; the Electrochemical Society of Japan}, journal = {Proceedings of the 5th East Asian Conference on Chemical Sensors; the 33rd Chemical Sensor Symposium : December 4 - 7, 2001, Huis Ten Bosch, Sasebo-shi, Nagasaki, Japan / Japan Association of Chemical Sensors; the Electrochemical Society of Japan}, publisher = {Japan Association of Chemical Sensors}, address = {Kasuga, Fukuoka-ken}, pages = {399 -- 401}, year = {2001}, language = {en} } @article{FunkeRoennaRobinson2008, author = {Funke, Harald and R{\"o}nna, Uwe and Robinson, A. E.}, title = {Development and testing of a 10 kW diffusive micromix combustor for hydrogen-fuelled μ-scale gas turbines}, series = {Proceedings of ASME Turbo Expo 2008: Power for Land, Sea and Air ; GT2008 ; June 9-13, 2008, Berlin, Germany}, journal = {Proceedings of ASME Turbo Expo 2008: Power for Land, Sea and Air ; GT2008 ; June 9-13, 2008, Berlin, Germany}, publisher = {ASME}, address = {New York, NY}, pages = {1 -- 8}, year = {2008}, language = {en} } @article{FunkeRobinsonHendricketal.2010, author = {Funke, Harald and Robinson, A. E. and Hendrick, P. and Wagemakers, R.}, title = {Design and Testing of a Micromix Combustor With Recuperative Wall Cooling for a Hydrogen Fuelled µ-Scale Gas Turbine}, series = {Proceedings of the ASME Turbo Expo 2010 : presented at the 2010 ASME Turbo Expo, June 14 - 18, 2010, Glasgow, UK / sponsored by the International Gas Turbine Institute / Vol. 5: Industrial and cogeneration ; microturbines and small turbomachinery ; oil and gas applications ; wind turbine technology}, journal = {Proceedings of the ASME Turbo Expo 2010 : presented at the 2010 ASME Turbo Expo, June 14 - 18, 2010, Glasgow, UK / sponsored by the International Gas Turbine Institute / Vol. 5: Industrial and cogeneration ; microturbines and small turbomachinery ; oil and gas applications ; wind turbine technology}, publisher = {ASME}, address = {New York, NY}, isbn = {978-0-7918-4400-7}, pages = {587 -- 596}, year = {2010}, language = {en} } @article{FunkeRobinson2007, author = {Funke, Harald and Robinson, A. E.}, title = {Development of a new test rig for a micro scale hydrogen combustion chamber}, series = {Proceedings of the 2nd European Conference for Aero-Space Sciences : July 1 - 6, 2007, Brussels, Belgium}, journal = {Proceedings of the 2nd European Conference for Aero-Space Sciences : July 1 - 6, 2007, Brussels, Belgium}, publisher = {-}, pages = {1 -- 8}, year = {2007}, language = {en} } @article{FunkeReckerBosschaertsetal.2011, author = {Funke, Harald and Recker, E. and Bosschaerts, W. and Boonen, Q. and B{\"o}rner, Sebastian}, title = {Parametrical study of the „Micromix" hydrogen combustion principle}, series = {10th International Symposium on Experimental and Computational Aerothermodynamics of Internal Flows, ISAIF10-049, Brussels, Belgium, 4-7 July 2011}, journal = {10th International Symposium on Experimental and Computational Aerothermodynamics of Internal Flows, ISAIF10-049, Brussels, Belgium, 4-7 July 2011}, year = {2011}, language = {en} } @article{FunkeKeinzKustereretal.2016, author = {Funke, Harald and Keinz, Jan and Kusterer, Karsten and Ayed, Anis Haj and Kazari, Masahide and Kitajima, Junichi and Horikawa, Atsushi and Okada, Kunio}, title = {Experimental and Numerical Study on Optimizing the Dry Low NOₓ Micromix Hydrogen Combustion Principle for Industrial Gas Turbine Applications}, series = {Journal of Thermal Science and Engineering Applications}, volume = {9}, journal = {Journal of Thermal Science and Engineering Applications}, number = {2}, publisher = {ASME}, address = {New York, NY}, issn = {1948-5093}, doi = {10.1115/1.4034849}, pages = {021001 -- 021001-10}, year = {2016}, abstract = {Combined with the use of renewable energy sources for its production, hydrogen represents a possible alternative gas turbine fuel for future low-emission power generation. Due to the difference in the physical properties of hydrogen compared to other fuels such as natural gas, well-established gas turbine combustion systems cannot be directly applied to dry low NOₓ (DLN) hydrogen combustion. The DLN micromix combustion of hydrogen has been under development for many years, since it has the promise to significantly reduce NOₓ emissions. This combustion principle for air-breathing engines is based on crossflow mixing of air and gaseous hydrogen. Air and hydrogen react in multiple miniaturized diffusion-type flames with an inherent safety against flashback and with low NOₓ emissions due to a very short residence time of the reactants in the flame region. The paper presents an advanced DLN micromix hydrogen application. The experimental and numerical study shows a combustor configuration with a significantly reduced number of enlarged fuel injectors with high-thermal power output at constant energy density. Larger fuel injectors reduce manufacturing costs, are more robust and less sensitive to fuel contamination and blockage in industrial environments. The experimental and numerical results confirm the successful application of high-energy injectors, while the DLN micromix characteristics of the design point, under part-load conditions, and under off-design operation are maintained. Atmospheric test rig data on NOₓ emissions, optical flame-structure, and combustor material temperatures are compared to numerical simulations and show good agreement. The impact of the applied scaling and design laws on the miniaturized micromix flamelets is particularly investigated numerically for the resulting flow field, the flame-structure, and NOₓ formation.}, language = {en} } @inproceedings{FunkeKeinzKustereretal.2015, author = {Funke, Harald and Keinz, Jan and Kusterer, K. and Haj Ayed, A. and Kazari, M. and Kitajima, J. and Horikawa, A. and Okada, K.}, title = {Experimental and Numerical Study on Optimizing the DLN Micromix Hydrogen Combustion Principle for Industrial Gas Turbine Applications}, series = {ASME Turbo Expo 2015: Turbine Technical Conference and Exposition Volume 4A: Combustion, Fuels and Emissions Montreal, Quebec, Canada, June 15-19, 2015}, booktitle = {ASME Turbo Expo 2015: Turbine Technical Conference and Exposition Volume 4A: Combustion, Fuels and Emissions Montreal, Quebec, Canada, June 15-19, 2015}, isbn = {978-0-7918-5668-0}, doi = {10.1115/GT2015-42043}, pages = {V04AT04A008}, year = {2015}, language = {en} } @inproceedings{FunkeKeinzHendrick2017, author = {Funke, Harald and Keinz, Jan and Hendrick, P.}, title = {Experimental Evaluation of the Pollutant and Noise Emissions of the GTCP 36-300 Gas Turbine Operated with Kerosene and a Low NOX Micromix Hydrogen Combustor}, series = {7th European Conference for Aeronautics and Space Sciences, EUCASS 2017}, booktitle = {7th European Conference for Aeronautics and Space Sciences, EUCASS 2017}, organization = {7th European Conference for Aeronautics and Space Sciences, EUCASS 2017-125, Milan, Italy, July 2017}, doi = {10.13009/EUCASS2017-125}, pages = {10 Seiten}, year = {2017}, language = {en} } @inproceedings{FunkeKeinzHajAyedetal.2015, author = {Funke, Harald and Keinz, Jan and Haj Ayed, A. and Kazari, M. and Kitajima, J. and Horikawa, A. and Okada, K.}, title = {Development and Testing of a Low NOx Micromix Combustion Chamber for an Industrial Gas Turbine}, series = {Proceedings of International Gas Turbine Congress 2015 Tokyo November 15-20, 2015, Tokyo, Japan}, booktitle = {Proceedings of International Gas Turbine Congress 2015 Tokyo November 15-20, 2015, Tokyo, Japan}, isbn = {978-4-89111-008-6}, pages = {131 -- 140}, year = {2015}, language = {en} } @inproceedings{FunkeKeinzBoerneretal.2013, author = {Funke, Harald and Keinz, Jan and B{\"o}rner, Sebastian and Haj Ayed, A. and Kusterer, K. and Tekin, N. and Kazari, M. and Kitajima, J. and Horikawa, A. and Okada, K.}, title = {Experimental and numerical characterization of the dry low NOx micromix hydrogen combustion principle at increased energy density for industrial hydrogen gas turbine applications}, series = {Combustion, fuels and emissions : proceedings of the ASME Turbo Expo: Turbine Technical Conference and Exposition - 2013 ; June 3 - 7, 2013, San Antonio, Texas, USA ; vol. 1}, booktitle = {Combustion, fuels and emissions : proceedings of the ASME Turbo Expo: Turbine Technical Conference and Exposition - 2013 ; June 3 - 7, 2013, San Antonio, Texas, USA ; vol. 1}, editor = {Song, Seung Jin}, publisher = {ASME}, address = {New York, NY}, organization = {American Society of Mechanical Engineers}, isbn = {978-0-7918-5510-2}, pages = {V001T04A055}, year = {2013}, language = {en} } @inproceedings{FunkeKeinzBoerneretal.2016, author = {Funke, Harald and Keinz, Jan and B{\"o}rner, S. and Hendrick, P. and Elsing, R.}, title = {Testing and analysis of the impact on engine cycle parameters and control system modifications using hydrogen or methane as fuel in an industrial gas turbine}, series = {Progress in propulsion physics ; Volume 8}, booktitle = {Progress in propulsion physics ; Volume 8}, publisher = {EDP Sciences}, address = {o.O.}, organization = {European Conference for Aerospace Sciences <2013, M{\"u}nchen>}, isbn = {978-5-94588-191-4}, doi = {10.1051/eucass/201608409}, pages = {409 -- 426}, year = {2016}, language = {en} } @inproceedings{FunkeHajAyedKustereretal.2014, author = {Funke, Harald and Haj Ayed, A. and Kusterer, K. and Keinz, Jan and Kazari, M. and Kitajima, J. and Horikawa, A. and Okada, K.}, title = {Numerical Study on Increased Energy Density for the DLN Micromix Hydrogen Combustion Principle}, series = {Combustion, Fuels and Emissions (ASME Turbo Expo 2014: Turbine Technical Conference and Exposition : D{\"u}sseldorf, Germany, June 16-20, 2014 ; Vol. 4A)}, booktitle = {Combustion, Fuels and Emissions (ASME Turbo Expo 2014: Turbine Technical Conference and Exposition : D{\"u}sseldorf, Germany, June 16-20, 2014 ; Vol. 4A)}, publisher = {ASME}, address = {New York, N.Y.}, isbn = {978-0-7918-4568-4}, pages = {V04AT04A057}, year = {2014}, language = {en} } @article{FunkeEschRoosen2022, author = {Funke, Harald and Esch, Thomas and Roosen, Petra}, title = {Powertrain Adaptions for LPG Usage in General Aviation}, series = {MTZ worldwide}, volume = {2022}, journal = {MTZ worldwide}, number = {83}, publisher = {Springer Nature}, address = {Basel}, doi = {10.1007/s38313-021-0756-6}, pages = {58 -- 62}, year = {2022}, abstract = {In general aviation, too, it is desirable to be able to operate existing internal combustion engines with fuels that produce less CO₂ than Avgas 100LL being widely used today It can be assumed that, in comparison, the fuels CNG, LPG or LNG, which are gaseous under normal conditions, produce significantly lower emissions. Necessary propulsion system adaptations were investigated as part of a research project at Aachen University of Applied Sciences.}, language = {en} } @inproceedings{FunkeEschRoosen2009, author = {Funke, Harald and Esch, Thomas and Roosen, Peter}, title = {Using motor gasoline for aircrafts - coping with growing bio-fuel-caused risks by understanding cause-effect relationship}, series = {Fuels 2009 : mineral oil based and alternative fuels ; 7th international colloquium ; January 14 - 15, 2009}, booktitle = {Fuels 2009 : mineral oil based and alternative fuels ; 7th international colloquium ; January 14 - 15, 2009}, editor = {Bartz, Wilfried J.}, publisher = {Technische Akademie Esslingen (TAE)}, address = {Ostfildern}, isbn = {978-3-924813-75-8}, pages = {237 -- 244}, year = {2009}, abstract = {The utilisation of vehicle-oriented gasoline in general aviation is very desirable for both ecological and economical reasons, as well as for general considerations of availability. As of today vehicle fuels may be used if the respective engine and cell are certified for such an operation. For older planes a supplementary technical certificate is provided for gasoline mixtures with less than 1 \% v/v ethanol only, though. Larger admixtures of ethanol may lead to sudden engine malfunction and should be considered as considerable security risks. Major problems are caused by the partially ethanol non-withstanding materials, a necessarily changed stochiometric adjustment of the engine for varying ethanol shares and the tendency for phase separation in the presence of absorbed water. The concepts of the flexible fuel vehicles are only partially applicable in the view of air security.}, language = {en} } @article{FunkeDickhoffKeinzetal.2014, author = {Funke, Harald and Dickhoff, J. and Keinz, Jan and Anis, H. A. and Parente, A. and Hendrick, P.}, title = {Experimental and numerical study of the micromix combustion principle applied for hydrogen and hydrogen-rich syngas as fuel with increased energy density for industrial gas turbine applications}, series = {Energy procedia}, journal = {Energy procedia}, number = {61}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1876-6102 (E-Journal)}, doi = {10.1016/j.egypro.2014.12.201}, pages = {1736 -- 1739}, year = {2014}, abstract = {The Dry Low NOx (DLN) Micromix combustion principle with increased energy density is adapted for the industrial gas turbine APU GTCP 36-300 using hydrogen and hydrogen-rich syngas with a composition of 90\%-Vol. hydrogen (H₂) and 10\%-Vol. carbon-monoxide (CO). Experimental and numerical studies of several combustor geometries for hydrogen and syngas show the successful advance of the DLN Micromix combustion from pure hydrogen to hydrogen-rich syngas. The impact of the different fuel properties on the combustion principle and aerodynamic flame stabilization design laws, flow field, flame structure and emission characteristics is investigated by numerical analysis using a hybrid Eddy Break Up combustion model and validated against experimental results.}, language = {en} } @article{FunkeBoernerRobinsonetal.2010, author = {Funke, Harald and B{\"o}rner, Sebastian and Robinson, A. and Hendrick, P. and Recker, E.}, title = {Low NOx H2 combustion for industrial gas turbines of various power ranges}, series = {5th International Gas Turbine Conference ETN-IGTC, ETN-2010-42, Brussels, Belgium, October 2010}, journal = {5th International Gas Turbine Conference ETN-IGTC, ETN-2010-42, Brussels, Belgium, October 2010}, year = {2010}, language = {en} } @article{FunkeBoernerKrebsetal.2011, author = {Funke, Harald and B{\"o}rner, Sebastian and Krebs, W. and Wolf, E.}, title = {Experimental Characterization of Low NOx Micromix Prototype Combustors for Industrial Gas Turbine Applications}, series = {ASME Turbo Expo 2011 ; Vancouver, Canada, June 6-10, 2011}, journal = {ASME Turbo Expo 2011 ; Vancouver, Canada, June 6-10, 2011}, year = {2011}, language = {en} } @inproceedings{FunkeBoernerKeinzetal.2012, author = {Funke, Harald and B{\"o}rner, Sebastian and Keinz, Jan and Kusterer, K. and Kroninger, D. and Kitajima, J. and Kazari, M. and Horikama, A.}, title = {Numerical and experimental characterization of low NOx Micromix combustion principle for industrial hydrogen gas turbine applications}, series = {Proceedings of ASME Turbo Expo 2012}, booktitle = {Proceedings of ASME Turbo Expo 2012}, pages = {11}, year = {2012}, language = {en} } @inproceedings{FunkeBoernerKeinzetal.2012, author = {Funke, Harald and B{\"o}rner, Sebastian and Keinz, Jan and Hendrick, P. and Recker, E.}, title = {Low NOx Hydrogen combustion chamber for industrial gas turbine applications", 14th International Symposium on Transport Phenomena and Dynamics of Rotating Machinery}, series = {ISROMAC-14 : the Forteenth International Symposium on Transport Phenomena and Dynamics of Rotating Machinery ; Honolulu, Hawaii, February 27 - March 02nd, 2012}, booktitle = {ISROMAC-14 : the Forteenth International Symposium on Transport Phenomena and Dynamics of Rotating Machinery ; Honolulu, Hawaii, February 27 - March 02nd, 2012}, year = {2012}, language = {en} } @inproceedings{FunkeBoernerHendricketal.2013, author = {Funke, Harald and B{\"o}rner, Sebastian and Hendrick, P. and Recker, E. and Elsing, R.}, title = {Development and integration of a scalable low NOx combustion chamber for a hydrogen fuelled aero gas turbine}, series = {Progress in Propulsion Physics. - Vol. 4}, booktitle = {Progress in Propulsion Physics. - Vol. 4}, editor = {DeLuca, Luigi T.}, publisher = {EDP Sciences}, address = {[Les Ulis]}, isbn = {978-2-7598-0876-2}, doi = {10.1051/eucass/201304357}, pages = {357 -- 372}, year = {2013}, language = {en} } @incollection{FunkeBoernerHendricketal.2011, author = {Funke, Harald and B{\"o}rner, Sebastian and Hendrick, P. and Recker, E.}, title = {Modification and testing of an engine and fuel control system for a hydrogen fuelled gas turbine}, series = {Progress in Propulsion Physics. Vol. 2}, booktitle = {Progress in Propulsion Physics. Vol. 2}, publisher = {EDP Sciences}, address = {Les Ulis}, isbn = {978-2-7598-0673-7}, pages = {475 -- 486}, year = {2011}, language = {en} } @article{FunkeBoernerFalketal.2011, author = {Funke, Harald and B{\"o}rner, Sebastian and Falk, F. and Hendrick, P.}, title = {Control system modifications and their effects on the operation of a hydrogen-fueled Auxiliary Power Unit}, series = {XX international symposium on air breathing engines 2011 : ISABE 2011, Gothenburg, Sweden, 12-16 September, 2011. Vol. 2.}, journal = {XX international symposium on air breathing engines 2011 : ISABE 2011, Gothenburg, Sweden, 12-16 September, 2011. Vol. 2.}, publisher = {American Institute of Aeronautics and Astronautics}, address = {Reston, VA}, isbn = {9781618391803}, pages = {929 -- 938}, year = {2011}, language = {en} } @inproceedings{FunkeBeckmannStefanetal.2023, author = {Funke, Harald and Beckmann, Nils and Stefan, Lukas and Keinz, Jan}, title = {Hydrogen combustor integration study for a medium range aircraft engine using the dry-low NOx "Micromix" combustion principle}, series = {Proceedings of the ASME Turbo Expo 2023: Turbomachinery Technical Conference and Exposition. Volume 1: Aircraft Engine.}, booktitle = {Proceedings of the ASME Turbo Expo 2023: Turbomachinery Technical Conference and Exposition. Volume 1: Aircraft Engine.}, publisher = {ASME}, address = {New York}, isbn = {978-0-7918-8693-9}, doi = {10.1115/GT2023-102370}, pages = {12 Seiten}, year = {2023}, abstract = {The feasibility study presents results of a hydrogen combustor integration for a Medium-Range aircraft engine using the Dry-Low-NOₓ Micromix combustion principle. Based on a simplified Airbus A320-type flight mission, a thermodynamic performance model of a kerosene and a hydrogen-powered V2530-A5 engine is used to derive the thermodynamic combustor boundary conditions. A new combustor design using the Dry-Low NOx Micromix principle is investigated by slice model CFD simulations of a single Micromix injector for design and off-design operation of the engine. Combustion characteristics show typical Micromix flame shapes and good combustion efficiencies for all flight mission operating points. Nitric oxide emissions are significant below ICAO CAEP/8 limits. For comparison of the Emission Index (EI) for NOₓ emissions between kerosene and hydrogen operation, an energy (kerosene) equivalent Emission Index is used. A full 15° sector model CFD simulation of the combustion chamber with multiple Micromix injectors including inflow homogenization and dilution and cooling air flows investigates the combustor integration effects, resulting NOₓ emission and radial temperature distributions at the combustor outlet. The results show that the integration of a Micromix hydrogen combustor in actual aircraft engines is feasible and offers, besides CO₂ free combustion, a significant reduction of NOₓ emissions compared to kerosene operation.}, language = {en} } @inproceedings{FunkeBeckmannKeinzetal.2021, author = {Funke, Harald and Beckmann, Nils and Keinz, Jan and Horikawa, Atsushi}, title = {30 years of dry low NOx micromix combustor research for hydrogen-rich fuels: an overview of past and present activities}, series = {Conference Proceedings Turbo Expo: Power for Land, Sea and Air, Volume 4B: Combustion, Fuels, and Emissions}, booktitle = {Conference Proceedings Turbo Expo: Power for Land, Sea and Air, Volume 4B: Combustion, Fuels, and Emissions}, publisher = {ASME}, address = {New York, NY}, isbn = {978-0-7918-8413-3}, doi = {10.1115/GT2020-16328}, pages = {14 Seiten}, year = {2021}, abstract = {The paper presents an overview of the past and present of low-emission combustor research with hydrogen-rich fuels at Aachen University of Applied Sciences. In 1990, AcUAS started developing the Dry-Low-NOx Micromix combustion technology. Micromix reduces NOx emissions using jet-in-crossflow mixing of multiple miniaturized fuel jets and combustor air with an inherent safety against flashback. At first, pure hydrogen as fuel was investigated with lab-scale applications. Later, Micromix prototypes were developed for the use in an industrial gas turbine Honeywell/Garrett GTCP-36-300, proving low NOx characteristics during real gas turbine operation, accompanied by the successful definition of safety laws and control system modifications. Further, the Micromix was optimized for the use in annular and can combustors as well as for fuel-flexibility with hydrogen-methane-mixtures and hydrogen-rich syngas qualities by means of extensive experimental and numerical simulations. In 2020, the latest Micromix application will be demonstrated in a commercial 2 MW-class gas turbine can-combustor with full-scale engine operation. The paper discusses the advances in Micromix research over the last three decades.}, language = {en} } @article{FunkeBeckmannKeinzetal.2019, author = {Funke, Harald and Beckmann, Nils and Keinz, Jan and Abanteriba, Sylvester}, title = {Numerical and Experimental Evaluation of a Dual-Fuel Dry-Low-NOx Micromix Combustor for Industrial Gas Turbine Applications}, series = {Journal of Thermal Science and Engineering Applications}, volume = {11}, journal = {Journal of Thermal Science and Engineering Applications}, number = {1}, publisher = {ASME}, address = {New York}, issn = {19485085}, doi = {10.1115/1.4041495}, pages = {011015}, year = {2019}, language = {en} } @article{FunkeBeckmannKeinzetal.2018, author = {Funke, Harald and Beckmann, Nils and Keinz, Jan and Abanteriba, Sylvester}, title = {Comparison of Numerical Combustion Models for Hydrogen and Hydrogen-Rich Syngas Applied for Dry-Low-Nox-Micromix-Combustion}, series = {Journal of Engineering for Gas Turbines and Power}, volume = {140}, journal = {Journal of Engineering for Gas Turbines and Power}, number = {8}, publisher = {ASME}, address = {New York, NY}, issn = {0742-4795}, doi = {10.1115/1.4038882}, pages = {9 Seiten}, year = {2018}, abstract = {The Dry-Low-NOx (DLN) Micromix combustion technology has been developed as low emission combustion principle for industrial gas turbines fueled with hydrogen or syngas. The combustion process is based on the phenomenon of jet-in-crossflow-mixing (JICF). Fuel is injected perpendicular into the air-cross-flow and burned in a multitude of miniaturized, diffusion-like flames. The miniaturization of the flames leads to a significant reduction of NOx emissions due to the very short residence time of reactants in the flame. In the Micromix research approach, computational fluid dynamics (CFD) analyses are validated toward experimental results. The combination of numerical and experimental methods allows an efficient design and optimization of DLN Micromix combustors concerning combustion stability and low NOx emissions. The paper presents a comparison of several numerical combustion models for hydrogen and hydrogen-rich syngas. They differ in the complexity of the underlying reaction mechanism and the associated computational effort. The performance of a hybrid eddy-break-up (EBU) model with a one-step global reaction is compared to a complex chemistry model and a flamelet generated manifolds (FGM) model, both using detailed reaction schemes for hydrogen or syngas combustion. Validation of numerical results is based on exhaust gas compositions available from experimental investigation on DLN Micromix combustors. The conducted evaluation confirms that the applied detailed combustion mechanisms are able to predict the general physics of the DLN-Micromix combustion process accurately. The FGM method proved to be generally suitable to reduce the computational effort while maintaining the accuracy of detailed chemistry.}, language = {en} } @inproceedings{FunkeBeckmannKeinzetal.2017, author = {Funke, Harald and Beckmann, Nils and Keinz, Jan and Abanteriba, Sylvester}, title = {Numerical and Experimental Evaluation of a Dual-Fuel Dry-Low-NOx Micromix Combustor for Industrial Gas Turbine Applications}, series = {Proceedings of the ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition. Volume 4B: Combustion, Fuels and Emissions. Charlotte, North Carolina, USA. June 26-30, 2017}, booktitle = {Proceedings of the ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition. Volume 4B: Combustion, Fuels and Emissions. Charlotte, North Carolina, USA. June 26-30, 2017}, publisher = {ASME}, address = {New York}, isbn = {978-0-7918-5085-5}, doi = {10.1115/GT2017-64795}, year = {2017}, abstract = {The Dry-Low-NOx (DLN) Micromix combustion technology has been developed originally as a low emission alternative for industrial gas turbine combustors fueled with hydrogen. Currently the ongoing research process targets flexible fuel operation with hydrogen and syngas fuel. The non-premixed combustion process features jet-in-crossflow-mixing of fuel and oxidizer and combustion through multiple miniaturized flames. The miniaturization of the flames leads to a significant reduction of NOx emissions due to the very short residence time of reactants in the flame. The paper presents the results of a numerical and experimental combustor test campaign. It is conducted as part of an integration study for a dual-fuel (H2 and H2/CO 90/10 Vol.\%) Micromix combustion chamber prototype for application under full scale, pressurized gas turbine conditions in the auxiliary power unit Honeywell Garrett GTCP 36-300. In the presented experimental studies, the integration-optimized dual-fuel Micromix combustor geometry is tested at atmospheric pressure over a range of gas turbine operating conditions with hydrogen and syngas fuel. The experimental investigations are supported by numerical combustion and flow simulations. For validation, the results of experimental exhaust gas analyses are applied. Despite the significantly differing fuel characteristics between pure hydrogen and hydrogen-rich syngas the evaluated dual-fuel Micromix prototype shows a significant low NOx performance and high combustion efficiency. The combustor features an increased energy density that benefits manufacturing complexity and costs.}, language = {en} } @article{FunkeBeckmannKeinzetal.2016, author = {Funke, Harald and Beckmann, Nils and Keinz, Jan and Abanteriba, Sylvester}, title = {Comparison of Numerical Combustion Models for Hydrogen and Hydrogen-Rich Syngas Applied for Dry-Low-NOx-Micromix-Combustion}, series = {ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition Volume 4A: Combustion, Fuels and Emissions Seoul, South Korea, June 13-17, 2016}, journal = {ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition Volume 4A: Combustion, Fuels and Emissions Seoul, South Korea, June 13-17, 2016}, publisher = {ASME}, address = {New York, NY}, isbn = {978-0-7918-4975-0}, doi = {10.1115/GT2016-56430}, pages = {12}, year = {2016}, abstract = {The Dry-Low-NOₓ (DLN) Micromix combustion technology has been developed as low emission combustion principle for industrial gas turbines fueled with hydrogen or syngas. The combustion process is based on the phenomenon of jet-in-crossflow-mixing. Fuel is injected perpendicular into the air-cross-flow and burned in a multitude of miniaturized, diffusion-like flames. The miniaturization of the flames leads to a significant reduction of NOₓ emissions due to the very short residence time of reactants in the flame. In the Micromix research approach, CFD analyses are validated towards experimental results. The combination of numerical and experimental methods allows an efficient design and optimization of DLN Micromix combustors concerning combustion stability and low NOₓ emissions. The paper presents a comparison of several numerical combustion models for hydrogen and hydrogen-rich syngas. They differ in the complexity of the underlying reaction mechanism and the associated computational effort. For pure hydrogen combustion a one-step global reaction is applied using a hybrid Eddy-Break-up model that incorporates finite rate kinetics. The model is evaluated and compared to a detailed hydrogen combustion mechanism derived by Li et al. including 9 species and 19 reversible elementary reactions. Based on this mechanism, reduction of the computational effort is achieved by applying the Flamelet Generated Manifolds (FGM) method while the accuracy of the detailed reaction scheme is maintained. For hydrogen-rich syngas combustion (H₂-CO) numerical analyses based on a skeletal H₂/CO reaction mechanism derived by Hawkes et al. and a detailed reaction mechanism provided by Ranzi et al. are performed. The comparison between combustion models and the validation of numerical results is based on exhaust gas compositions available from experimental investigation on DLN Micromix combustors. The conducted evaluation confirms that the applied detailed combustion mechanisms are able to predict the general physics of the DLN-Micromix combustion process accurately. The Flamelet Generated Manifolds method proved to be generally suitable to reduce the computational effort while maintaining the accuracy of detailed chemistry. Especially for reaction mechanisms with a high number of species accuracy and computational effort can be balanced using the FGM model.}, language = {en} } @inproceedings{FunkeBeckmannAbanteriba2017, author = {Funke, Harald and Beckmann, Nils and Abanteriba, Sylvester}, title = {A comparison of complex chemistry mechanisms for hydrogen methane blends based on the Sandia / Sydney Bluff-Body Flame HM1}, series = {Proceedings of the Eleventh Asia-Pacific Conference on Combustion (ASPACC 2017), New South Wales, Australia, 10-14 December 2017}, booktitle = {Proceedings of the Eleventh Asia-Pacific Conference on Combustion (ASPACC 2017), New South Wales, Australia, 10-14 December 2017}, isbn = {978-1-5108-5646-2}, pages = {262 -- 265}, year = {2017}, language = {en} } @inproceedings{FunkeBeckmannAbanteriba2019, author = {Funke, Harald and Beckmann, Nils and Abanteriba, Sylvester}, title = {Development and Testing of a FuelFlex Dry-Low-NOx Micromix Combustor for Industrial Gas Turbine Applications With Variable Hydrogen Methane Mixtures}, series = {ASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition. June 17-21, 2019 Phoenix, Arizona, USA. Volume 4A: Combustion, Fuels, and Emissions}, booktitle = {ASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition. June 17-21, 2019 Phoenix, Arizona, USA. Volume 4A: Combustion, Fuels, and Emissions}, isbn = {978-0-7918-5861-5}, doi = {10.1115/GT2019-90095}, pages = {11 Seiten}, year = {2019}, language = {en} } @article{FunkeBeckmannAbanteriba2019, author = {Funke, Harald and Beckmann, Nils and Abanteriba, Sylvester}, title = {An overview on dry low NOx micromix combustor development for hydrogen-rich gas turbine applications}, series = {International Journal of Hydrogen Energy}, volume = {44}, journal = {International Journal of Hydrogen Energy}, number = {13}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0360-3199}, doi = {10.1016/j.ijhydene.2019.01.161}, pages = {6978 -- 6990}, year = {2019}, language = {en} } @article{FunkeBeckmann2022, author = {Funke, Harald and Beckmann, Nils}, title = {Flexible fuel operation of a Dry-Low-NOx Micromix Combustor with Variable Hydrogen Methane Mixture}, series = {International Journal of Gas Turbine, Propulsion and Power Systems}, volume = {13}, journal = {International Journal of Gas Turbine, Propulsion and Power Systems}, number = {2}, issn = {1882-5079}, pages = {1 -- 7}, year = {2022}, abstract = {The role of hydrogen (H2) as a carbon-free energy carrier is discussed since decades for reducing greenhouse gas emissions. As bridge technology towards a hydrogen-based energy supply, fuel mixtures of natural gas or methane (CH4) and hydrogen are possible. The paper presents the first test results of a low-emission Micromix combustor designed for flexible-fuel operation with variable H2/CH4 mixtures. The numerical and experimental approach for considering variable fuel mixtures instead of recently investigated pure hydrogen is described. In the experimental studies, a first generation FuelFlex Micromix combustor geometry is tested at atmospheric pressure at gas turbine operating conditions corresponding to part- and full-load. The H2/CH4 fuel mixture composition is varied between 57 and 100 vol.\% hydrogen content. Despite the challenges flexible-fuel operation poses onto the design of a combustion system, the evaluated FuelFlex Micromix prototype shows a significant low NOx performance}, language = {en} } @inproceedings{FunkeBeckmann2019, author = {Funke, Harald and Beckmann, Nils}, title = {Flexible Fuel Operation of a Dry-Low-Nox Micromix Combustor with Variable Hydrogen Methane Mixtures}, series = {Proceedings of International Gas Turbine Congress 2019 Tokyo, November 17-22, 2019, Tokyo, Japan}, booktitle = {Proceedings of International Gas Turbine Congress 2019 Tokyo, November 17-22, 2019, Tokyo, Japan}, isbn = {978-4-89111-010-9}, year = {2019}, language = {en} } @article{FuestKotliarWalteretal.2014, author = {Fuest, Matthias and Kotliar, Konstantin and Walter, Peter and Plange, Niklas}, title = {Monitoring intraocular pressure changes after intravitreal Ranibizumab injection using rebound tonometry}, series = {Ophthalmic and physiological optics}, volume = {34}, journal = {Ophthalmic and physiological optics}, number = {4}, publisher = {Wiley-Blackwell}, address = {Oxford}, issn = {1475-1313 (E-Journal); 0275-5408 (Print)}, doi = {10.1111/opo.12134}, pages = {438 -- 444}, year = {2014}, language = {en} } @inproceedings{FuchsRitzStrauch2012, author = {Fuchs, Britta and Ritz, Thomas and Strauch, Jakob}, title = {Usability of mobile applications : dissemination of usability engineering in small and medium enterprises}, series = {Proceedings of the International Conference on Data Communication Networking, e-Business and Optical Communication Systems : Rome, Italy, 24 - 27 July, 2012 ; [integrated in the ICETE (International Conference on e-Business and Telecommunications)]}, booktitle = {Proceedings of the International Conference on Data Communication Networking, e-Business and Optical Communication Systems : Rome, Italy, 24 - 27 July, 2012 ; [integrated in the ICETE (International Conference on e-Business and Telecommunications)]}, editor = {Obaidat, Mohammad S.}, publisher = {SciTePress}, address = {[Lissabon]}, isbn = {978-989-8565-23-5}, pages = {272 -- 277}, year = {2012}, language = {en} } @inproceedings{FuchsRitzHalbachetal.2011, author = {Fuchs, Britta and Ritz, Thomas and Halbach, Bastian and Hartl, Florian}, title = {Blended shopping : interactivity and individualization}, series = {Proceedings of the International Conference on e-Business : Seville, Spain, 18 - 21 July 2011 ; [... integrated in the ICETE (International Conference on e-Business and Telecommunications) joint conference]}, booktitle = {Proceedings of the International Conference on e-Business : Seville, Spain, 18 - 21 July 2011 ; [... integrated in the ICETE (International Conference on e-Business and Telecommunications) joint conference]}, editor = {Marca, David A.}, publisher = {SciTePress}, address = {[Lissabon]}, isbn = {978-989-8425-70-6}, pages = {47 -- 52}, year = {2011}, language = {en} } @inproceedings{FuchsRitz2014, author = {Fuchs, Britta and Ritz, Thomas}, title = {Usability for Blended Shopping - Solving Major Flaws by Applying Usability Engineering and Proven Integration Technologies}, series = {Proceedings of the 11th International Conference on e-Business, ICE-B 2014, Vienna, Austria}, booktitle = {Proceedings of the 11th International Conference on e-Business, ICE-B 2014, Vienna, Austria}, isbn = {978-989-758-043-7}, doi = {10.5220/0005113502160223}, pages = {216 -- 223}, year = {2014}, language = {en} } @article{FrotscherStaat2014, author = {Frotscher, Ralf and Staat, Manfred}, title = {Stresses produced by different textile mesh implants in a tissue equivalent}, series = {BioNanoMaterials}, volume = {15}, journal = {BioNanoMaterials}, number = {1-2}, publisher = {De Gruyter}, address = {Berlin}, issn = {2191-4672 (E-Journal); 2193-066X (E-Journal); 0011-8656 (Print); 1616-0177 (Print); 2193-0651 (Print)}, doi = {10.1515/bnm-2014-0003}, pages = {25 -- 30}, year = {2014}, abstract = {Two single-incision mini-slings used for treating urinary incontinence in women are compared with respect to the stresses they produce in their surrounding tissue. In an earlier paper we experimentally observed that these implants produce considerably different stress distributions in a muscle tissue equivalent. Here we perform 2D finite element analyses to compare the shear stresses and normal stresses in the tissue equivalent for the two meshes and to investigate their failure behavior. The results clearly show that the Gynecare TVT fails for increasing loads in a zipper-like manner because it gradually debonds from the surrounding tissue. Contrary to that, the tissue at the ends of the DynaMesh-SIS direct may rupture but only at higher loads. The simulation results are in good agreement with the experimental observations thus the computational model helps to interpret the experimental results and provides a tool for qualitative evaluation of mesh implants.}, language = {en} } @incollection{FrotscherStaat2018, author = {Frotscher, Ralf and Staat, Manfred}, title = {Towards Patient-Specific Computational Modeling of hiPS-Derived Cardiomyocyte Function and Drug Action}, series = {Biological, Physical and Technical Basics of Cell Engineering}, booktitle = {Biological, Physical and Technical Basics of Cell Engineering}, editor = {Artmann, Gerhard and Temiz Artmann, Ayseg{\"u}l and Zhubanova, Azhar A. and Digel, Ilya}, publisher = {Springer}, address = {Singapore}, isbn = {978-981-10-7904-7}, doi = {10.1007/978-981-10-7904-7_10}, pages = {233 -- 250}, year = {2018}, abstract = {Human-induced pluripotent stem cell-derived cardiomyocytes (hiPS-CM) today are widely used for the investigation of normal electromechanical cardiac function, of cardiac medication and of mutations. Computational models are thus established that simulate the behavior of this kind of cells. This section first motivates the modeling of hiPS-CM and then presents and discusses several modeling approaches of microscopic and macroscopic constituents of human-induced pluripotent stem cell-derived and mature human cardiac tissue. The focus is led on the mapping of the computational results one can achieve with these models onto mature human cardiomyocyte models, the latter being the real matter of interest. Model adaptivity is the key feature that is discussed because it opens the way for modeling various biological effects like biological variability, medication, mutation and phenotypical expression. We compare the computational with experimental results with respect to normal cardiac function and with respect to inotropic and chronotropic drug effects. The section closes with a discussion on the status quo of the specificity of computational models and on what challenges have to be solved to reach patient-specificity.}, language = {en} } @inproceedings{FrotscherStaat2015, author = {Frotscher, Ralf and Staat, Manfred}, title = {An electromechanical model for cardiac tissue constructs}, series = {Conference proceedings of the YIC GACM 2015 : 3rd ECCOMAS Young Investigators Conference and 6th GACM Colloquium on Computational Mechanics , Aachen, 20.07.2015 - 23.07.2015 / ed.: Stefanie Elgeti ; Jaan-Willem Simon}, booktitle = {Conference proceedings of the YIC GACM 2015 : 3rd ECCOMAS Young Investigators Conference and 6th GACM Colloquium on Computational Mechanics , Aachen, 20.07.2015 - 23.07.2015 / ed.: Stefanie Elgeti ; Jaan-Willem Simon}, publisher = {RWTH Aachen University}, address = {Aachen}, organization = {ECCOMAS Young Investigators Conference <3, 2015, Aachen>}, pages = {1 -- 4}, year = {2015}, language = {en} } @inproceedings{FrotscherStaat2015, author = {Frotscher, Ralf and Staat, Manfred}, title = {Homogenization of a cardiac tissue construct}, series = {CMBE15 : 4th International Conference on Computational \& Mathematical Biomedical Engineering ; 29th June - 1st July 2015 ; {\´E}cole Normale Sup{\´e}rieure de Cachan ; Cachan (Paris), France}, booktitle = {CMBE15 : 4th International Conference on Computational \& Mathematical Biomedical Engineering ; 29th June - 1st July 2015 ; {\´E}cole Normale Sup{\´e}rieure de Cachan ; Cachan (Paris), France}, editor = {Nithiarasu, Perumal}, publisher = {CMBE}, address = {[s.l.]}, issn = {2227-9385}, pages = {645 -- 648}, year = {2015}, language = {en} } @inproceedings{FrotscherRaatschenStaat2012, author = {Frotscher, Ralf and Raatschen, Hans-J{\"u}rgen and Staat, Manfred}, title = {Effectiveness of the edge-based smoothed finite element method applied to soft biological tissues}, series = {ESMC-2012 - 8th European Solid Mechanics Conference, Graz, Austria, July 9-13, 2012}, booktitle = {ESMC-2012 - 8th European Solid Mechanics Conference, Graz, Austria, July 9-13, 2012}, editor = {Holzapfel, Gerhard A.}, publisher = {Verlag d. Technischen Universit{\"a}t Graz}, address = {Graz}, isbn = {978-3-85125-223-1}, year = {2012}, language = {en} } @inproceedings{FrotscherRaatschenStaat2012, author = {Frotscher, Ralf and Raatschen, Hans-J{\"u}rgen and Staat, Manfred}, title = {Application of an edge-based smoothed finite element method on geometrically non-linear plates of non-linear material}, series = {Proceedings European Congress on Computational Methods in Applied Sciences and Engineering (ECCOMAS 2012)}, booktitle = {Proceedings European Congress on Computational Methods in Applied Sciences and Engineering (ECCOMAS 2012)}, editor = {Eberhardsteiner, J.}, year = {2012}, language = {en} } @article{FrotscherMuanghongDursunetal.2016, author = {Frotscher, Ralf and Muanghong, Danita and Dursun, G{\"o}zde and Goßmann, Matthias and Temiz Artmann, Ayseg{\"u}l and Staat, Manfred}, title = {Sample-specific adaption of an improved electro-mechanical model of in vitro cardiac tissue}, series = {Journal of Biomechanics}, volume = {49}, journal = {Journal of Biomechanics}, number = {12}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0021-9290 (Print)}, doi = {10.1016/j.jbiomech.2016.01.039}, pages = {2428 -- 2435}, year = {2016}, abstract = {We present an electromechanically coupled computational model for the investigation of a thin cardiac tissue construct consisting of human-induced pluripotent stem cell-derived atrial, ventricular and sinoatrial cardiomyocytes. The mechanical and electrophysiological parts of the finite element model, as well as their coupling are explained in detail. The model is implemented in the open source finite element code Code_Aster and is employed for the simulation of a thin circular membrane deflected by a monolayer of autonomously beating, circular, thin cardiac tissue. Two cardio-active drugs, S-Bay K8644 and veratridine, are applied in experiments and simulations and are investigated with respect to their chronotropic effects on the tissue. These results demonstrate the potential of coupled micro- and macroscopic electromechanical models of cardiac tissue to be adapted to experimental results at the cellular level. Further model improvements are discussed taking into account experimentally measurable quantities that can easily be extracted from the obtained experimental results. The goal is to estimate the potential to adapt the presented model to sample specific cell cultures.}, language = {en} } @article{FrotscherKochStaat2015, author = {Frotscher, Ralf and Koch, Jan-Peter and Staat, Manfred}, title = {Computational investigation of drug action on human-induced stem cell derived cardiomyocytes}, series = {Journal of biomechanical engineering}, volume = {Vol. 137}, journal = {Journal of biomechanical engineering}, number = {iss. 7}, publisher = {ASME}, address = {New York}, issn = {1528-8951 (E-Journal); 0148-0731 (Print)}, doi = {10.1115/1.4030173}, pages = {071002-1 -- 071002-7}, year = {2015}, language = {en} } @inproceedings{FrotscherKochRaatschenetal.2014, author = {Frotscher, Ralf and Koch, Jan-Peter and Raatschen, Hans-J{\"u}rgen and Staat, Manfred}, title = {Evaluation of a computational model for drug action on cardiac tissue}, series = {11th World Congress on Computational Mechanics (WCCM XI) ; 5th European Conference on Computational Mechanics (ECCM V) ; 6th European Conference on Computational Fluid Dynamics (ECFD VI) ; July 20 - 25, 2014, Barcelona}, booktitle = {11th World Congress on Computational Mechanics (WCCM XI) ; 5th European Conference on Computational Mechanics (ECCM V) ; 6th European Conference on Computational Fluid Dynamics (ECFD VI) ; July 20 - 25, 2014, Barcelona}, editor = {Onate, E.}, organization = {World Congress on Computational Mechanics <11, 2014, Barcelona>}, pages = {1 -- 12}, year = {2014}, language = {en} } @inproceedings{FrotscherGossmannTemizArtmannetal.2013, author = {Frotscher, Ralf and Goßmann, Matthias and Temiz Artmann, Ayseg{\"u}l and Staat, Manfred}, title = {Simulation of cardiac cell-seeded membranes using the edge-based smoothed FEM}, series = {1st International Conference "Shell and Membrane Theories in Mechanics and Biology: From Macro- to Nanoscale Structures", Minsk, Belarus, Sept. 16-20, 2013}, booktitle = {1st International Conference "Shell and Membrane Theories in Mechanics and Biology: From Macro- to Nanoscale Structures", Minsk, Belarus, Sept. 16-20, 2013}, publisher = {Verl. d. Weißruss. Staatl. Univ.}, address = {Minsk}, organization = {International Conference Shell and Membrane Theories in Mechanics and Biology: From Macro- to Nanoscale Structures <1, 2013, Minsk>}, isbn = {978-985-553-135-8}, pages = {165 -- 167}, year = {2013}, language = {en} } @incollection{FrotscherGossmannRaatschenetal.2015, author = {Frotscher, Ralf and Goßmann, Matthias and Raatschen, Hans-J{\"u}rgen and Temiz Artmann, Ayseg{\"u}l and Staat, Manfred}, title = {Simulation of cardiac cell-seeded membranes using the edge-based smoothed FEM}, series = {Shell and membrane theories in mechanics and biology. (Advanced structured materials ; 45)}, booktitle = {Shell and membrane theories in mechanics and biology. (Advanced structured materials ; 45)}, publisher = {Springer}, address = {Heidelberg}, isbn = {978-3-319-02534-6 ; 978-3-319-02535-3}, pages = {187 -- 212}, year = {2015}, abstract = {We present an electromechanically coupled Finite Element model for cardiac tissue. It bases on the mechanical model for cardiac tissue of Hunter et al. that we couple to the McAllister-Noble-Tsien electrophysiological model of purkinje fibre cells. The corresponding system of ordinary differential equations is implemented on the level of the constitutive equations in a geometrically and physically nonlinear version of the so-called edge-based smoothed FEM for plates. Mechanical material parameters are determined from our own pressure-deflection experimental setup. The main purpose of the model is to further examine the experimental results not only on mechanical but also on electrophysiological level down to ion channel gates. Moreover, we present first drug treatment simulations and validate the model with respect to the experiments.}, language = {en} } @inproceedings{FrotscherDuongStaat2015, author = {Frotscher, Ralf and Duong, Minh Tuan and Staat, Manfred}, title = {Simulating beating cardiomyocytes with electromechanical coupling}, series = {II. International Conference on Biomedical Technology : 28-30 October 2015 Hannover, Germany / T. Lenarz, P. Wriggers (Eds.)}, booktitle = {II. International Conference on Biomedical Technology : 28-30 October 2015 Hannover, Germany / T. Lenarz, P. Wriggers (Eds.)}, organization = {International Conference on Biomedical Technology <2, 2015, Hannover>}, pages = {1 -- 2}, year = {2015}, language = {en} } @phdthesis{Frotscher2016, author = {Frotscher, Ralf}, title = {Electromechanical modeling and simulation of thin cardiac tissue constructs - smoothed FEM applied to a biomechanical plate problem}, year = {2016}, language = {en} } @article{FrohbergAnik1983, author = {Frohberg, Martin G. and Anik, Sabri}, title = {The application of a quadi-chemical lattice model to binary metallic solvents containing oxygen in higher concentrations}, series = {Zeitschrift f{\"u}r Metallkunde}, volume = {74}, journal = {Zeitschrift f{\"u}r Metallkunde}, number = {10}, issn = {0044-3093}, pages = {665 -- 666}, year = {1983}, language = {en} } @article{FrohbergAnik1985, author = {Frohberg, Martin G. and Anik, Sabri}, title = {The calculation of component activities of binary metallic melts from their gas solubilities}, series = {Zeitschrift f{\"u}r Metallkunde}, volume = {76}, journal = {Zeitschrift f{\"u}r Metallkunde}, number = {2}, issn = {0044-3093}, pages = {135 -- 137}, year = {1985}, language = {en} } @article{FrohbergAnik1985, author = {Frohberg, Martin G. and Anik, Sabri}, title = {Thermodynamic relations between component activities and gas solubilities in binary metallic systems}, series = {Berichte der Bunsengesellschaft f{\"u}r physikalische Chemie}, volume = {89}, journal = {Berichte der Bunsengesellschaft f{\"u}r physikalische Chemie}, number = {2}, issn = {0940-483X}, pages = {130 -- 134}, year = {1985}, language = {en} } @inproceedings{FrickeZiolkoAnthrakidisetal.2012, author = {Fricke, Barbara and Ziolko, C. and Anthrakidis, Anette and Alexopoulos, Spiros and Hoffschmidt, Bernhard and Giese, F. and Dillig, M.}, title = {InnoSol - environmental aspects of the open volumetric receiver technology}, series = {30th ISES Biennial Solar World Congress 2011 : : Kassel, Germany, 28 August - 2 September 2011. Vol. 5}, booktitle = {30th ISES Biennial Solar World Congress 2011 : : Kassel, Germany, 28 August - 2 September 2011. Vol. 5}, publisher = {Curran}, address = {Red Hook, NY}, organization = {International Solar Energy Society}, pages = {3895 -- 3900}, year = {2012}, language = {en} } @inproceedings{FrickeZiolkoAnthrakidisetal.2011, author = {Fricke, Barbara and Ziolko, C. and Anthrakidis, Anette and Alexopoulos, Spiros and Hoffschmidt, Bernhard and Dillig, M. and Giese, F.}, title = {InnoSol - life cycle analysis of solar power tower plants}, series = {SolarPACES 2011 : concentrating solar power and chemical energy systems : 20 - 23 September, 2011, Granada, Spain}, booktitle = {SolarPACES 2011 : concentrating solar power and chemical energy systems : 20 - 23 September, 2011, Granada, Spain}, address = {Granada}, pages = {1 CD-ROM}, year = {2011}, language = {en} } @inproceedings{FrickeHoffschmidt2010, author = {Fricke, Barbara and Hoffschmidt, Bernhard}, title = {Ecobalance of a solar thermal tower power plant with volumetric receiver}, series = {SolarPACES 2010 : the CSP Conference: electricity, fuels and clean water from concentrated solar energy ; 21 to 24 September 2010, Perpignan, France}, booktitle = {SolarPACES 2010 : the CSP Conference: electricity, fuels and clean water from concentrated solar energy ; 21 to 24 September 2010, Perpignan, France}, publisher = {Soc. OSC}, address = {Saint Maur}, pages = {87 -- 88}, year = {2010}, language = {en} } @inproceedings{FreyerThewesMeinecke2023, author = {Freyer, Nils and Thewes, Dustin and Meinecke, Matthias}, title = {GUIDO: a hybrid approach to guideline discovery \& ordering from natural language texts}, series = {Proceedings of the 12th International Conference on Data Science, Technology and Applications DATA - Volume 1}, booktitle = {Proceedings of the 12th International Conference on Data Science, Technology and Applications DATA - Volume 1}, editor = {Gusikhin, Oleg and Hammoudi, Slimane and Cuzzocrea, Alfredo}, isbn = {978-989-758-664-4}, issn = {2184-285X}, doi = {10.5220/0012084400003541}, pages = {335 -- 342}, year = {2023}, abstract = {Extracting workflow nets from textual descriptions can be used to simplify guidelines or formalize textual descriptions of formal processes like business processes and algorithms. The task of manually extracting processes, however, requires domain expertise and effort. While automatic process model extraction is desirable, annotating texts with formalized process models is expensive. Therefore, there are only a few machine-learning-based extraction approaches. Rule-based approaches, in turn, require domain specificity to work well and can rarely distinguish relevant and irrelevant information in textual descriptions. In this paper, we present GUIDO, a hybrid approach to the process model extraction task that first, classifies sentences regarding their relevance to the process model, using a BERT-based sentence classifier, and second, extracts a process model from the sentences classified as relevant, using dependency parsing. The presented approach achieves significantly better resul ts than a pure rule-based approach. GUIDO achieves an average behavioral similarity score of 0.93. Still, in comparison to purely machine-learning-based approaches, the annotation costs stay low.}, language = {en} } @incollection{FreyerKempt2023, author = {Freyer, Nils and Kempt, Hendrik}, title = {AI-DSS in healthcare and their power over health-insecure collectives}, series = {Justice in global health}, booktitle = {Justice in global health}, editor = {Bhakuni, Himani and Miotto, Lucas}, publisher = {Routledge}, address = {London}, isbn = {9781003399933}, doi = {10.4324/9781003399933-4}, pages = {38 -- 55}, year = {2023}, abstract = {AI-based systems are nearing ubiquity not only in everyday low-stakes activities but also in medical procedures. To protect patients and physicians alike, explainability requirements have been proposed for the operation of AI-based decision support systems (AI-DSS), which adds hurdles to the productive use of AI in clinical contexts. This raises two questions: Who decides these requirements? And how should access to AI-DSS be provided to communities that reject these standards (particularly when such communities are expert-scarce)? This chapter investigates a dilemma that emerges from the implementation of global AI governance. While rejecting global AI governance limits the ability to help communities in need, global AI governance risks undermining and subjecting health-insecure communities to the force of the neo-colonial world order. For this, this chapter first surveys the current landscape of AI governance and introduces the approach of relational egalitarianism as key to (global health) justice. To discuss the two horns of the referred dilemma, the core power imbalances faced by health-insecure collectives (HICs) are examined. The chapter argues that only strong demands of a dual strategy towards health-secure collectives can both remedy the immediate needs of HICs and enable them to become healthcare independent.}, language = {en} } @article{FredebeulKreinVogel2006, author = {Fredebeul-Krein, Markus and Vogel, Erika}, title = {Underground Storage Facilities in the German natural gas market: A need for access regulation to ensure competition?}, series = {Zeitschrift f{\"u}r Energiewirtschaft. 30 (2006), H. 4}, journal = {Zeitschrift f{\"u}r Energiewirtschaft. 30 (2006), H. 4}, isbn = {0343-5377}, pages = {257 -- 270}, year = {2006}, language = {en} } @inproceedings{FredebeulKreinSteingroever2013, author = {Fredebeul-Krein, Markus and Steingr{\"o}ver, Markus}, title = {Enhancing broadband development and internet usages for improving networks and services in APEC member economies: Bridging the digital divide}, series = {The 19th ITS Biennial Conference 2012 "Moving Forward with Future Technologies: Opening a Platform for All" 18 - 21 November 2012, Thailand}, booktitle = {The 19th ITS Biennial Conference 2012 "Moving Forward with Future Technologies: Opening a Platform for All" 18 - 21 November 2012, Thailand}, publisher = {ITS}, address = {Bangkok}, pages = {13 S.}, year = {2013}, language = {en} } @article{FredebeulKreinSteingroever2009, author = {Fredebeul-Krein, Markus and Steingr{\"o}ver, Markus}, title = {Next Generation Access Networks: Why is there a higher risk of investment and how to deal with it?}, series = {Wettbewerbsprobleme im Internet / J{\"o}rn Kruse ... (Hrsg.). Mit Beitr. von: Patrick F. E. Beschorner ...}, journal = {Wettbewerbsprobleme im Internet / J{\"o}rn Kruse ... (Hrsg.). Mit Beitr. von: Patrick F. E. Beschorner ...}, publisher = {Nomos, Ed. Fischer}, address = {Baden-Baden}, isbn = {978-3-8329-5024-8}, pages = {83 -- 102}, year = {2009}, language = {en} } @inproceedings{FredebeulKreinSteingroever2012, author = {Fredebeul-Krein, Markus and Steingr{\"o}ver, Markus}, title = {Wholesale Broadband Access to IPTV in an NGA environment : how to deal with it from a regulatory perspective?}, pages = {1 -- 16}, year = {2012}, language = {en} } @article{FredebeulKreinSteingroever2014, author = {Fredebeul-Krein, Markus and Steingr{\"o}ver, Markus}, title = {Wholesale broadband access to IPTV in an NGA environment : how to deal with it from a regulatory perspective?}, series = {Telecommunications Policy}, volume = {38}, journal = {Telecommunications Policy}, number = {3}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0308-5961 (Print)}, doi = {doi:10.1016/j.telpol.2013.04.002}, pages = {264 -- 277}, year = {2014}, language = {en} } @article{FredebeulKreinKnoben2010, author = {Fredebeul-Krein, Markus and Knoben, Werner}, title = {Long term risk sharing contracts as an approach to establish public-private partnerships for investment into next generation access networks}, series = {Telecommunications Policy}, volume = {34}, journal = {Telecommunications Policy}, number = {9}, isbn = {0308-5961}, pages = {528 -- 539}, year = {2010}, language = {en} } @inproceedings{FredebeulKreinHaunert2008, author = {Fredebeul-Krein, Markus and Haunert, Martina}, title = {Assessing the effectiveness of price cap regimes for the regulation of fixed telephony markets: has it been successful in achieving competition? : preliminary draft / by Markus Fredebeul-Krein and Martina Haunert. 19th European Regional ITS Conference of the International Telecommunications Society, September 17-19, 2008 Rome, Italy}, year = {2008}, abstract = {1. Introduction 2. Tariff regulation, rebalancing and price caps 3. Price cap regimes in selected European countries 4. Has price cap regulation been successful? 5. Regulatory implications for other countries}, subject = {Telekommunikationsmarkt}, language = {en} } @article{FredebeulKrein1999, author = {Fredebeul-Krein, Markus}, title = {The case for a more binding WTO agreement on regulatory principles in telecommunication markets}, series = {Telecommunications policy. vol. 23 (1999), H. afl. 9}, journal = {Telecommunications policy. vol. 23 (1999), H. afl. 9}, isbn = {0308-5961}, pages = {625 -- 644}, year = {1999}, language = {en} } @article{FredebeulKrein1997, author = {Fredebeul-Krein, Markus}, title = {Telecommunications and WTO discipline : an assessment of the WTO agreement on telecommunication services}, series = {Telecommunications policy. 21 (1997), H. 6}, journal = {Telecommunications policy. 21 (1997), H. 6}, isbn = {0308-5961}, pages = {477 -- 491}, year = {1997}, language = {en} } @inproceedings{FredebeulKrein2008, author = {Fredebeul-Krein, Markus}, title = {Time for revision: The regulation of Germany's next generation networks in the light of new economic and technological challenges on telecom markets : Presentation for the 18th Biennial conference of the International Telecommunications Society, June 24-27, 2008 Montreal, Canada}, year = {2008}, abstract = {On 1st January 1998, the German telecom market was fully liberalised. Since then genuine competition between market participants has developed, based on a comprehensive legal and regulatory framework that provides for safeguards against unfair competition and market power by Deutsche Telekom. Today, about 10 years after the liberalisation of the telecommunications sector a revision of this regulatory approach has become necessary because at least on three dimensions the situation is quite different from the one 10 years ago: First, with numerous established alternative operators in the market monopolies have been successfully challenged and competition introduced. Second, not only is Cable TV becoming in large parts of Germany a viable alternative for the provision of broadband services but also mobile services are becoming increasingly a substitute for fixed services. Last but not least there are important technological changes under way, requiring huge investments in infrastructure upgrades for next generation networks. In the light of these new developments the question is to which extent the current regulatory approach of severe ex-ante regulatory intervention is still appropriate. Is any part of the network of the former incumbent still a bottleneck? A more light handed regulatory approach might be the right response to this new situation. The paper is organised as follows: The first section will briefly examine the economic rationale for regulating network access. Based on the assumption that regulation is always necessary when bottlenecks exist regulatory principles for an efficient network access regime will be derived. The second section compares the situation of the German market in early 1998 with the one of today. Thereby three dimensions will be considered: the degree of competition, the potential for substitution and technological developments. The third section will define some requirements for the future regulation of telecom markets. Proposals will be elaborated how to ensure competitive telecom markets in the light of new economic and technological challenges.}, subject = {Telekommunikationsmarkt}, language = {en} } @inproceedings{FredebeulKrein2006, author = {Fredebeul-Krein, Markus}, title = {Developing competitive broadband markets: Lessons learnt from German and European regulatory approaches on broad-band access}, year = {2006}, abstract = {A key feature of future broadband markets will be diversity of access technologies, meaning that numerous technologies will be exploited for broadband communication. Various factors will affect the success of these future broadband markets, the regulatory policy being one amongst others. So far, a coherent regulatory approach does not exist as to broadband markets. First results of policies so far suggest that less sector-specific regulation is likely to occur. Instead, regulators must ensure that access to networks and services of potentially dominant providers in a relevant broadband market will satisfy requirements for openness and non-discrimination. In this environment the future challenge of regulationg broadband markets will be to set the right incentives for investment into new infrastructures. This paper examines whether there is a need for the regulation of future broadband access markets an if yes, what is the appropriate regulatory tool to do so. Thereby the focus is on the analysis of European broadband markets and the regulatory approaches applied. The first section provides a description of the characteristics of future broadband markets. The second section discusses possible bottlenecks on broadband markets an their regulatory implications. The third section will examine regulatory issues concerning access to broadband networks in more detail. This will be done by comparing the regulatory approaches of European countries and the results in terms of bradband penetration. The final section will give key recommendations for a regulatory strategy on brandband access markets.}, subject = {Telekommunikationsmarkt}, language = {en} } @inproceedings{FredebeulKrein2007, author = {Fredebeul-Krein, Markus}, title = {10 years of liberalised telecom markets in Germany: Assessing the degree of competition on the markets for voice telephony}, year = {2007}, abstract = {Market data for the German telecom market shows that Deutsche Telekom as the former incumbent is constantly loosing shares on all arkets for voice telephony: the market for local calls, the market for long-distance calls and the market for international calls. At the same time prices decline steadily with the latest trend being that operators offer voice services free of charge, the costs of which are covered by a monthly subscription charge. Against this background the paper examines the state of policy and regulatory reform in the telecommunications sector in Germany almost 10 years after the liberalisation of the fixed telecommunications market. Thereby the focus is on the analysis of the competitive conditions that have been established on the German market for voice telephony services. If these retail markets are competitive, there might be a need to remove remaining regulatory provisions. In the new environment of converging markets the future challenge of regulating fixed telecom markets might be to ensure that access to the network and/or services of a potentially dominant provider in a relevant market will satisfy requirements for openness and non-discrimination.}, subject = {Telekommunikationsmarkt}, language = {en} } @inproceedings{FredebeulKrein2009, author = {Fredebeul-Krein, Markus}, title = {Encouraging competition and investment into next generation access networks: The case of long term risk sharing contracts}, year = {2009}, abstract = {Working paper distributed at 2nd Annual Next Generation Telecommunications Conference 2009, 13th - 14th October 2009, Brussels 14 pages Abstract Governments all over Europe are in the process of adopting new broadband strategies. The objective is to create modern telecommunications networks based on powerful broadband infrastructures". In doing so, they aim for innovative and investment-friendly concepts. For instance, in a recently published consultation paper on the subject the German regulator BNetzA declared that it will take "greater account of … reducing risks, securing the investment and innovation power, providing planning certainty and transparency - in order to support and advance broadband rollout in Germany". It further states that when regulating wholesale rates it has to be ensured that "… adequate incentives for network rollout are provided on the one hand, while sustainable and fair competition is ensured on the other". Also an EC draft recommendation on regulated network access is about to set new standards for the regulation of next generation access networks. According to the recommendation the prices of new assets shall be based on costs plus a projectspecific risk premium to be included in the costs of capital for the investment risk incurred by the operator. This approach has been criticised from various sides. In particular it has been questioned whether such an approach is adequate to meet the objectives of encouraging both competition and investment into next generation access networks. Against this background, the concept of "long term risk sharing contracts" has been proposed recently as an approach which does not only incorporate the various additional risks involved in the deployment of NGA infrastructure, but has several other advantages. This paper will demonstrate that the concept allows for competition to evolve at both the retail and wholesale level on fair, objective, non-discriminatory and transparent terms and conditions. Moreover, it ensures the highest possible investment incentive in line with socially desirable outcome. The paper is organised as follows: The next section will briefly outline the importance of encouraging competition and investment in an NGA-environment. The third section will specify the design of long term risk sharing contracts in view of achieving these objectives. The fourth section will examine potential problems associated with the concept. In doing so a way of how to deal with them will be elaborated. The last section will look at arguments against long term risk sharing contracts. It will be shown that these arguments are not strong enough to build a case against introducing such contracts.}, subject = {Electronic Commerce}, language = {en} } @article{FredebeulKrein2003, author = {Fredebeul-Krein, Markus}, title = {Adopting a coherent institutional framework for the Ukrainian telecom sector: Lessons to be learnt from European and German experience}, series = {Zerkalo Nedeli (2003)}, journal = {Zerkalo Nedeli (2003)}, year = {2003}, language = {en} } @article{FredebeulKrein2002, author = {Fredebeul-Krein, Markus}, title = {Regulating Prices of Unbundled Access to the Local Loop: A German Case Study}, series = {Telekomunikacja i techniki informacyjne (2002)}, journal = {Telekomunikacja i techniki informacyjne (2002)}, isbn = {1640-1549}, pages = {10 -- 18}, year = {2002}, language = {en} } @inproceedings{FredebeulKrein2016, author = {Fredebeul-Krein, Markus}, title = {Towards trade facilitation via regulatory convergence: An analysis of the TTIP chapter on Electronic Communications}, series = {Regional ITS Conference of the International Telecommunications Society. Cambridge, United Kingdom, 7-9 September 2016}, booktitle = {Regional ITS Conference of the International Telecommunications Society. Cambridge, United Kingdom, 7-9 September 2016}, pages = {29 Seiten}, year = {2016}, abstract = {To give the exchange of goods and services between the European Union (EU) and the United States (U.S.) new momentum the two parties are currently negotiating the transatlantic free trade agreement Transatlantic Trade and Investment Partnership (TTIP). The aim is to create the largest free trade area in the world. The agreement, once entered into force, will oblige EU countries and the U.S. to further liberalize their markets. The negotiations on TTIP include a chapter on Electronic Communications/ Telecommunications. The challenge therein will be securing commitments for market access to Electronic Communications services. At the same time, these commitments must reflect the legitimate need for consumer protection issues. The need to reduce Electronic Communications-related non-tariff barriers to trade between the Parties is due to the fact that these markets are heavily regulated. Without transnational rules as to regulations national governments can abuse these regulations to deter the market entry by new (foreign) suppliers. Thus the free trade agreement TTIP affects in many respects regulatory provisions on and access to Electronic Communications markets. The objective of this paper is therefore to examine to what extend the regulatory principles for Electronic Communications markets envisaged under TTIP will result in trade facilitation and regulatory convergence between the EU and the U.S. As to this question the result of the analysis is that the chapter on Electronic Communications will be an important step towards facilitating trade in Electronic Communications services. At the same time some regulatory convergence will take place, but this convergence will not lead to a (full) harmonization of regulations. Rather the norm, also after TTIP negotiations will have been concluded successfully, will be mutual recognition of different regulatory regimes. Different regulations being the optimal policy response in different market settings will continue to exist. Moreover, it is very unlikely that such regulatory principles for the Electronic Communications sector are a vehicle for a race to the bottom in levels of consumer protection.}, language = {en} } @misc{FrauenrathRenzRiegeretal.2010, author = {Frauenrath, Tobias and Renz, Wolfgang and Rieger, Jan and G{\"o}mmel, Andreas and Butenweg, Christoph and Niendorf, Thoralf}, title = {High Spatial Resolution 3D MRI of the Larynx Using a Dedicated TX/RX Phased Array Coil at 7.0T}, series = {2010 ISMRM-ESMRMB joint annual meeting}, journal = {2010 ISMRM-ESMRMB joint annual meeting}, issn = {1545-4428}, year = {2010}, abstract = {MRI holds great potential for elucidating laryngeal and vocal fold anatomy together with the assessment of physiological processes associated in human phonation. However, MRI of human phonation remains very challenging due to the small size of the targeted structures, interfering signal from fat, air between the vocal folds and surrounding muscles and physiological motion. These anatomical/physiological constraints translate into stringent technical requirements in balancing, scan time, image contrast, immunity to physiological motion, temporal resolution and spatial resolution. Motivated by these challenges and limitations this study is aiming at translating the sensitivity gain at ultra-high magnetic fields for enhanced high spatial resolution 3D imaging of the larynx and vocal tract. To approach this goal a dedicated two channel TX/RX larynx coil is being proposed.}, language = {en} } @misc{FrauenrathPfeifferHezeletal.2012, author = {Frauenrath, Tobias and Pfeiffer, Harald and Hezel, Fabian and Dieringer, Matthias A. and Winter, Lukas and Gr{\"a}ßl, Andreas and Santoro, Davide and {\"O}zerdem, Celal and Renz, Wolfgang and Greiser, Andreas and Niendorf, Thoralf}, title = {Lessons learned from cardiac MRI at 7.0 T: LV function assessment at 3.0 T using local multi-channel transceiver coil arrays}, series = {2012 ISMRM Annual Meeting Proceedings}, journal = {2012 ISMRM Annual Meeting Proceedings}, issn = {1545-4428}, year = {2012}, abstract = {Cardiac MR (CMR) is of proven clinical value but also an area of vigorous ongoing research since image quality is not always exclusively defined by signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). Recent developments of CMR at 7.0 T have been driven by pioneering explorations into novel multichannel transmit and receive coil array technology to tackle the challenges B1+-field inhomogeneities, to offset specific-absorption rate (SAR) constraints and to reduce banding artifacts in SSFP imaging. For this study, recognition of the benefits and performance of local surface Tx/Rx-array structures recently established at 7.0 T inspired migration to 3.0 T, where RF inhomogeneities and SAR limitations encountered in routine clinical CMR, though somewhat reduced versus the 7.0 T situation, remain significant. For all these reasons, this study was designed to build and examine the feasibility of a local four channel Tx/Rx cardiac coil array for anatomical and functional cardiac imaging at 3.0 T. For comparison, a homebuilt 4 channel Rx cardiac coil array exhibiting the same geometry as the Tx/Rx coil and a Rx surface coil array were used.}, language = {en} } @article{FrauenrathNiendorfKob2008, author = {Frauenrath, Tobias and Niendorf, Thoralf and Kob, Malte}, title = {Acoustic method for synchronization of Magnetic Resonance Imaging (MRI)}, series = {Acta Acustica}, volume = {94}, journal = {Acta Acustica}, number = {1}, publisher = {Hirzel}, address = {Stuttgart}, issn = {1861-9959}, doi = {10.3813/AAA.918017}, pages = {148 -- 155}, year = {2008}, abstract = {Magnetic Resonance Imaging (MRI) of moving organs requires synchronization with physiological motion or flow, which dictate the viable window for data acquisition. To meet this challenge, this study proposes an acoustic gating device (ACG) that employs acquisition and processing of acoustic signals for synchronization while providing MRI compatibility, immunity to interferences with electro-magnetic and acoustic fields and suitability for MRI at high magnetic field strengths. The applicability and robustness of the acoustic gating approach is examined in a pilot study, where it substitutes conventional ECG-gating for cardiovascular MR. The merits and limitations of the ACG approach are discussed. Implications for MR imaging in the presence of physiological motion are considered including synchronization with other structure- or motion borne sounds.}, language = {en} } @article{FrauenrathHezelRenzetal.2010, author = {Frauenrath, Tobias and Hezel, Fabian and Renz, Wolfgang and de Geyer d'Orth, Thibaut and Dieringer, Matthias and von Knobelsdorf-Brenkenhoff, Florian and Prothmann, Marcel and Schulz-Menger, Jeanette and Niendorf, Thoralf}, title = {Acoustic cardiac triggering: a practical solution for synchronization and gating of cardiovascular magnetic resonance at 7 Tesla}, series = {Journal of Cardiovascular Magnetic Resonance}, volume = {12}, journal = {Journal of Cardiovascular Magnetic Resonance}, number = {1}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1532-429X}, doi = {10.1186/1532-429X-12-67}, year = {2010}, abstract = {Background To demonstrate the applicability of acoustic cardiac triggering (ACT) for imaging of the heart at ultrahigh magnetic fields (7.0 T) by comparing phonocardiogram, conventional vector electrocardiogram (ECG) and traditional pulse oximetry (POX) triggered 2D CINE acquisitions together with (i) a qualitative image quality analysis, (ii) an assessment of the left ventricular function parameter and (iii) an examination of trigger reliability and trigger detection variance derived from the signal waveforms. Results ECG was susceptible to severe distortions at 7.0 T. POX and ACT provided waveforms free of interferences from electromagnetic fields or from magneto-hydrodynamic effects. Frequent R-wave mis-registration occurred in ECG-triggered acquisitions with a failure rate of up to 30\% resulting in cardiac motion induced artifacts. ACT and POX triggering produced images free of cardiac motion artefacts. ECG showed a severe jitter in the R-wave detection. POX also showed a trigger jitter of approximately Δt = 72 ms which is equivalent to two cardiac phases. ACT showed a jitter of approximately Δt = 5 ms only. ECG waveforms revealed a standard deviation for the cardiac trigger offset larger than that observed for ACT or POX waveforms. Image quality assessment showed that ACT substantially improved image quality as compared to ECG (image quality score at end-diastole: ECG = 1.7 ± 0.5, ACT = 2.4 ± 0.5, p = 0.04) while the comparison between ECG vs. POX gated acquisitions showed no significant differences in image quality (image quality score: ECG = 1.7 ± 0.5, POX = 2.0 ± 0.5, p = 0.34). Conclusions The applicability of acoustic triggering for cardiac CINE imaging at 7.0 T was demonstrated. ACT's trigger reliability and fidelity are superior to that of ECG and POX. ACT promises to be beneficial for cardiovascular magnetic resonance at ultra-high field strengths including 7.0 T.}, language = {en} } @article{FrauenrathHezelHeinrichsetal.2009, author = {Frauenrath, Tobias and Hezel, Fabian and Heinrichs, Uwe and Kozerke, Sebastian and Utting, Jane and Kob, Malte and Butenweg, Christoph and Boesiger, Peter and Niendorf, Thoralf}, title = {Feasibility of Cardiac Gating Free of Interference With Electro-Magnetic Fields at 1.5 Tesla, 3.0 Tesla and 7.0 Tesla Using an MR-Stethoscope}, series = {Investigative Radiology}, volume = {44}, journal = {Investigative Radiology}, number = {9}, publisher = {Lippincott Williams \& Wilkins ; (via Ovid)}, address = {Philadelphia, Pa}, issn = {1536-0210 (online)}, doi = {10.1097/RLI.0b013e3181b4c15e}, pages = {539 -- 547}, year = {2009}, language = {en} } @inproceedings{FrauenrathGoemmelButenwegetal.2010, author = {Frauenrath, Tobias and G{\"o}mmel, Andreas and Butenweg, Christoph and Otten, Mario and Niendorf, Thoralf}, title = {3D mapping of vocal fold geometry during articulatory maneuvers using ultrashort echo time imaging at 3.0 T}, series = {ISMRM-ESMRMB joint annual meeting 2010, Band 4}, booktitle = {ISMRM-ESMRMB joint annual meeting 2010, Band 4}, publisher = {Curran}, address = {Red Hook, NY}, organization = {International Society of Magnetic Resonance in Medicine}, isbn = {978-1-617-82008-3}, pages = {3087}, year = {2010}, language = {en} } @misc{FrauenrathFuchsHezeletal.2012, author = {Frauenrath, Tobias and Fuchs, Katharina and Hezel, Fabian and Dieringer, Matthias A. and Rieger, Jan and Niendorf, Thoralf}, title = {Improved cardiac triggering by combining multiple physiological signals: a cardiac MR feasibility study at 7.0 T}, series = {2012 ISMRM Annual Meeting Proceedings}, journal = {2012 ISMRM Annual Meeting Proceedings}, issn = {1545-4428}, year = {2012}, abstract = {In current clinical cardiovascular MR (CMR) practice cardiac motion is commonly dealt with using ECG based synchronization. However, ECG is corrupted by magneto-hydrodynamic (MHD) effects in magnetic fields. This leads to artifacts in the ECG trace and evokes severe T-wave elevations, which might be misinterpreted as R-waves resulting in erroneous triggering. At (ultra)high field strengths, the propensity of ECG recordings to MHD effects is further pronounced. Pulse oximetry (POX) being inherently sensitive to blood oxygenation provides an alternative approach for cardiac gating. However, due to the travel time of the blood the peak of maximum oxygenation and hence the trigger is delayed by approx. 300 ms with respect to the ECG's R-wave. Also the peak of maximum oxygenation shows a jitter of up to 65 ms. Alternative triggering approaches include acoustic cardiac triggering (ACT). In current clinical practice cardiac gating / triggering commonly relies on using single physiological signals only. Realizing this limitation this study proposes a combined triggering approach which exploits multiple physiological signals including ECG, POX or ACT to track cardiac activity. The feasibility of the coupled approach is examined for LV function assessment at 7.0 T. For this purpose, breath-held 2D-CINE imaging in conjunction with cardiac synchronization was performed paralleled by real time logging of physiological waveforms to track (mis)synchronization between the cardiac cycle and data acquisition. Combinations of the ECG, POX and ACT signals were evaluated and processed in real time to facilitate reliable trigger information.}, language = {en} } @article{FrauenrathFuchsDieringeretal.2012, author = {Frauenrath, Tobias and Fuchs, Katharina and Dieringer, Matthias A. and {\"O}zerdem, Celal and Patel, Nishan and Renz, Wolfgang and Greiser, Andreas and Elgeti, Thomas and Niendorf, Thoralf}, title = {Detailing the use of magnetohydrodynamic effects for synchronization of MRI with the cardiac cycle: A feasibility study}, series = {Journal of Magnetic Resonance Imaging}, volume = {36}, journal = {Journal of Magnetic Resonance Imaging}, number = {2}, publisher = {Wiley-Liss}, address = {New York}, issn = {1522-2586}, doi = {10.1002/jmri.23634}, pages = {364 -- 372}, year = {2012}, abstract = {Purpose: To investigate the feasibility of using magnetohydrodynamic (MHD) effects for synchronization of magnetic resonance imaging (MRI) with the cardiac cycle. Materials and Methods: The MHD effect was scrutinized using a pulsatile flow phantom at B0 = 7.0 T. MHD effects were examined in vivo in healthy volunteers (n = 10) for B0 ranging from 0.05-7.0 T. Noncontrast-enhanced MR angiography (MRA) of the carotids was performed using a gated steady-state free-precession (SSFP) imaging technique in conjunction with electrocardiogram (ECG) and MHD synchronization. Results: The MHD potential correlates with flow velocities derived from phase contrast MRI. MHD voltages depend on the orientation between B0 and the flow of a conductive fluid. An increase in the interelectrode spacing along the flow increases the MHD potential. In vivo measurement of the MHD effect provides peak voltages of 1.5 mV for surface areas close to the common carotid artery at B0 = 7.0 T. Synchronization of MRI with the cardiac cycle using MHD triggering is feasible. MHD triggered MRA of the carotids at 3.0 T showed an overall image quality and richness of anatomic detail, which is comparable to ECG-triggered MRAs. Conclusion: This feasibility study demonstrates the use of MHD effects for synchronization of MR acquisitions with the cardiac cycle. J. Magn. Reson. Imaging 2012;36:364-372. © 2012 Wiley Periodicals, Inc.}, language = {en} } @misc{FrauenrathDieringerPateletal.2011, author = {Frauenrath, Tobias and Dieringer, Matthias and Patel, Nishant and Zerdem, Celal and Hentschel, Jan and Renz, Wolfgang and Niendorf, Thoralf}, title = {From Artifact to Merit: Cardiac Gated MRI at 7T \& 3T using Magneto-Hydrodynamic Effects for Synchronization}, series = {2011 ISMRM Annual Meeting Proceedings}, journal = {2011 ISMRM Annual Meeting Proceedings}, issn = {1545-4428}, year = {2011}, abstract = {ECG is corrupted by magneto-hydrodynamic effects at higher magnetic field strength. Artifacts in the ECG trace and severe T-wave elevation might be mis-interpreted as R-waves. MHD being inherently sensitive to blood flow and blood velocity provides an alternative approach for cardiac gating, even in peripheral target areas far away from the commonly used upper torso positions of ECG electrodes. This feature would be very beneficial to address traveling time induced motion artifacts and trigger latency related issues raised by ECG-gated peripheral MR angiography. For all those reasons, this work proposes the use of MHD-trigger for cardiac gated MR.}, language = {en} } @misc{FrauenrathdeGeyerd'OrthNiendorf2011, author = {Frauenrath, Tobias and de Geyer d'Orth, Thibaut and Niendorf, Thoralf}, title = {Assessment of Accuracy \& Reproducibility of ECG, Pulse Oximetry \& Phonocardiogram Gating of Cardiac MRI at 7T}, series = {2011 ISMRM Annual Meeting Proceedings}, journal = {2011 ISMRM Annual Meeting Proceedings}, issn = {1545-4428}, year = {2011}, abstract = {At (ultra)high magnetic fields the artifact sensitivity of ECG recordings increases. This bears the risk of R-wave mis-registration which has been consistently reported for ECG triggered CMR at 7.0T. Realizing the constraints of conventional ECG, acoustic cardiac triggering (ACT) has been proposed. The clinical ACT has not been carefully examined yet. For this reason, this work scrutinizes the suitability, accuracy and reproducibility of ACT for CMR at 7.0T. For this purpose, the trigger reliability and trigger detection variance are examined together with an qualitative and quantitative assessment of image quality of the heart at 7.0T.}, language = {en} } @misc{FrauenrathBeckerHezeletal.2010, author = {Frauenrath, Tobias and Becker, Meike and Hezel, Fabian and Krombach, Gabriele A. and Kremer, Ute and Schulz-Menger, Jeanette and Niendorf, Thoralf}, title = {Comparison of Left Function Assessment Using Phonocardiogram and Electrocardiogram Triggered 2D SSFP CINE MR Imaging at 1.5 T and 3.0 T}, series = {2010 ISMRM-ESMRMB joint annual meeting}, journal = {2010 ISMRM-ESMRMB joint annual meeting}, issn = {1545-4428}, year = {2010}, abstract = {As high-field cardiac MRI (CMR) becomes more widespread the propensity of ECG to distortions and mistriggering increases and with it the motivation for a cardiac triggering alternative. Hence, this study explores the suitability of acoustic cardiac triggering (ACT) for left ventricular (LV) function assessment in healthy subjects at 1.5T and 3.0T.}, language = {en} } @article{FranzenPindersPfaffetal.2018, author = {Franzen, Julius and Pinders, Erik and Pfaff, Raphael and Enning, Manfred}, title = {RailCrowd's virtual fleets: Make most of your asset data}, series = {Deine Bahn}, journal = {Deine Bahn}, number = {9}, publisher = {Bahn-Fachverlag}, address = {Berlin}, issn = {0948-7263}, pages = {11 -- 13}, year = {2018}, abstract = {For smaller railway operators or those with a diverse fleet, it can be difficult to collect sufficient data to improve maintenance programs. At the same time, new rules such as entity in charge of maintenance - ECM - regulations impose an additional workload by requiring a dedicated maintenance management system and specific reports. The RailCrowd platform sets out to facilitate compliance with ECM and similar regulations while at the same time pooling anonymised fleet data across operators to form virtual fleets, providing greater data insights.}, language = {en} } @incollection{FranzenSteckenPfaffetal.2019, author = {Franzen, Julian and Stecken, Jannis and Pfaff, Raphael and Kuhlenk{\"o}tter, Bernd}, title = {Using the Digital Shadow for a Prescriptive Optimization of Maintenance and Operation : The Locomotive in the Context of the Cyber-Physical System}, series = {Advances in Production, Logistics and Traffic}, booktitle = {Advances in Production, Logistics and Traffic}, publisher = {Springer}, address = {Cham}, isbn = {978-3-030-13535-5}, doi = {10.1007/978-3-030-13535-5_19}, pages = {265 -- 276}, year = {2019}, abstract = {In competition with other modes of transport, rail freight transport is looking for solutions to become more attractive. Short-term success can be achieved through the data-driven optimization of operations and maintenance as well as the application of novel strategies such as prescriptive maintenance. After introducing the concept of prescriptive maintenance, this paper aims to prove that vehicle-focused applications of this approach indeed have the potential to increase attractiveness. However, even greater advantages can be activated if data from the horizontal network of the vehicle is available. Drawing on the state of the art in research and technology in the field of cyber-physical systems (CPS) as well as digital twins and shadows, our work serves to design a system of systems for the horizontal interconnection of a rail vehicle and to conceptualize a draft for a digital twin of a locomotive.}, language = {en} } @inproceedings{FrantzBinderBuschetal.2020, author = {Frantz, Cathy and Binder, Matthias and Busch, Konrad and Ebert, Miriam and Heinrich, Andreas and Kaczmarkiewicz, Nadine and Schl{\"o}gl-Knothe, B{\"a}rbel and Kunze, Tobias and Schuhbauer, Christian and Stetka, Markus and Schwager, Christian and Spiegel, Michael and Teixeira Boura, Cristiano Jos{\´e} and Bauer, Thomas and Bonk, Alexander and Eisen, Stefan and Funck, Bernhard}, title = {Basic Engineering of a High Performance Molten Salt Tower Receiver System}, series = {AIP Conference Proceedings}, booktitle = {AIP Conference Proceedings}, doi = {10.1063/5.0085895}, pages = {1 -- 10}, year = {2020}, abstract = {The production of dispatchable renewable energy will be one of the most important key factors of the future energy supply. Concentrated solar power (CSP) plants operated with molten salt as heat transfer and storage media are one opportunity to meet this challenge. Due to the high concentration factor of the solar tower technology the maximum process temperature can be further increased which ultimately decreases the levelized costs of electricity of the technology (LCOE). The development of an improved tubular molten salt receiver for the next generation of molten salt solar tower plants is the aim of this work. The receiver is designed for a receiver outlet temperature up to 600 °C. Together with a complete molten salt system, the receiver will be integrated into the Multi-Focus-Tower (MFT) in J{\"u}lich (Germany). The paper describes the basic engineering of the receiver, the molten salt tower system and a laboratory corrosion setup.}, language = {en} } @article{FrankoDuKallweitetal.2020, author = {Franko, Josef and Du, Shengzhi and Kallweit, Stephan and Duelberg, Enno Sebastian and Engemann, Heiko}, title = {Design of a Multi-Robot System for Wind Turbine Maintenance}, series = {Energies}, volume = {13}, journal = {Energies}, number = {10}, publisher = {MDPI}, address = {Basel}, issn = {1996-1073}, doi = {10.3390/en13102552}, pages = {Article 2552}, year = {2020}, abstract = {The maintenance of wind turbines is of growing importance considering the transition to renewable energy. This paper presents a multi-robot-approach for automated wind turbine maintenance including a novel climbing robot. Currently, wind turbine maintenance remains a manual task, which is monotonous, dangerous, and also physically demanding due to the large scale of wind turbines. Technical climbers are required to work at significant heights, even in bad weather conditions. Furthermore, a skilled labor force with sufficient knowledge in repairing fiber composite material is rare. Autonomous mobile systems enable the digitization of the maintenance process. They can be designed for weather-independent operations. This work contributes to the development and experimental validation of a maintenance system consisting of multiple robotic platforms for a variety of tasks, such as wind turbine tower and rotor blade service. In this work, multicopters with vision and LiDAR sensors for global inspection are used to guide slower climbing robots. Light-weight magnetic climbers with surface contact were used to analyze structure parts with non-destructive inspection methods and to locally repair smaller defects. Localization was enabled by adapting odometry for conical-shaped surfaces considering additional navigation sensors. Magnets were suitable for steel towers to clamp onto the surface. A friction-based climbing ring robot (SMART— Scanning, Monitoring, Analyzing, Repair and Transportation) completed the set-up for higher payload. The maintenance period could be extended by using weather-proofed maintenance robots. The multi-robot-system was running the Robot Operating System (ROS). Additionally, first steps towards machine learning would enable maintenance staff to use pattern classification for fault diagnosis in order to operate safely from the ground in the future.}, language = {en} } @article{FrankeStreckertBitzetal.2005, author = {Franke, Helmut and Streckert, Joachim and Bitz, Andreas and Goeke, Johannes and Hansen, Volkert and Ringelstein, E. Bernd and Nattk{\"a}mper, Heiner and Galle, Hans-Joachim and St{\"o}gbauer, Florian}, title = {Effects of Universal Mobile Telecommunications System (UMTS) electromagnetic fields on the blood-brain barrier in vitro}, series = {Radiation Research}, volume = {164}, journal = {Radiation Research}, number = {3}, issn = {1938-5404}, doi = {10.1667/RR3424.1}, pages = {258 -- 269}, year = {2005}, language = {en} } @article{ForstKaragiannisLuebbenetal.2008, author = {Forst, Thomas and Karagiannis, E. and L{\"u}bben, G. and Hohberg, C. and Sch{\"o}ndorf, T. and Dikta, Gerhard and Drexler, M. and Morcos, M. and D{\"a}nschel, W. and Borchert, M. and Pf{\"u}tzner, A.}, title = {Pleiotrophic and anti-inflammatory effects of pioglitazone precede the metabolic activity in type 2 diabetic patients with coronary artery disease}, series = {Atherosclerosis. 197 (2008), H. 1}, journal = {Atherosclerosis. 197 (2008), H. 1}, issn = {0021-9150}, doi = {10.1016/j.atherosclerosis.2007.05.006}, pages = {311 -- 317}, year = {2008}, language = {en} } @article{FontivonArxGarciaGonzalezetal.2010, author = {Fonti, Patrick and von Arx, Georg and Garc{\´i}a-Gonz{\´a}lez, Ignacio and Eilmann, Britta and Sass-Klaassen, Ute G. W. and G{\"a}rtner, Holger and Eckstein, Dieter}, title = {Studying global change through investigation of the plastic responses of xylem anatomy in tree rings}, series = {New Phytologist}, volume = {185}, journal = {New Phytologist}, number = {1}, publisher = {Wiley-Blackwell}, address = {Oxford}, issn = {1469-8137 (Online)}, doi = {10.1111/j.1469-8137.2009.03030.x}, pages = {42 -- 53}, year = {2010}, abstract = {Variability in xylem anatomy is of interest to plant scientists because of the role water transport plays in plant performance and survival. Insights into plant adjustments to changing environmental conditions have mainly been obtained through structural and functional comparative studies between taxa or within taxa on contrasting sites or along environmental gradients. Yet, a gap exists regarding the study of hydraulic adjustments in response to environmental changes over the lifetimes of plants. In trees, dated tree-ring series are often exploited to reconstruct dynamics in ecological conditions, and recent work in which wood-anatomical variables have been used in dendrochronology has produced promising results. Environmental signals identified in water-conducting cells carry novel information reflecting changes in regional conditions and are mostly related to short, sub-annual intervals. Although the idea of investigating environmental signals through wood anatomical time series goes back to the 1960s, it is only recently that low-cost computerized image-analysis systems have enabled increased scientific output in this field. We believe that the study of tree-ring anatomy is emerging as a promising approach in tree biology and climate change research, particularly if complemented by physiological and ecological studies. This contribution presents the rationale, the potential, and the methodological challenges of this innovative approach.}, language = {en} } @article{FontiEilmannGarciaGonzalezetal.2009, author = {Fonti, Patrick and Eilmann, Britta and Garc{\´i}a-Gonz{\´a}lez, Ignacio and von Arx, Georg}, title = {Expeditious building of ring-porous earlywood vessel chronologies without loosing signal information}, series = {Trees : structure and function}, volume = {23}, journal = {Trees : structure and function}, number = {3}, publisher = {Springer}, address = {Berlin}, issn = {0931-1890 (Print)}, doi = {10.1007/s00468-008-0310-z}, pages = {665 -- 671}, year = {2009}, language = {en} } @article{FoltzSchneiderWolfetal.2008, author = {Foltz, Christian and Schneider, Nicole and Wolf, Martin R. and Kausch, Bernhard and Schlick, Christopher and Luczak, Holger}, title = {Usability engineering}, series = {Collaborative and distributed chemical engineering : from understanding to substantial design process support; results of the IMPROVE Project. - (Lecture notes in computer science ; 4970)}, journal = {Collaborative and distributed chemical engineering : from understanding to substantial design process support; results of the IMPROVE Project. - (Lecture notes in computer science ; 4970)}, editor = {Nagl, Manfred}, publisher = {Springer}, address = {Berlin}, isbn = {978-3-540-70552-9}, doi = {10.1007/978-3-540-70552-9_21}, pages = {527 -- 554}, year = {2008}, language = {en} } @article{FleischhakerKraussSchaettigeretal.2013, author = {Fleischhaker, Robert and Krauß, Nico and Sch{\"a}ttiger, Farina and Dekorsy, Thomas}, title = {Consistent characterization of semiconductor saturable absorber mirrors with singe-pulse and pump-probe spectroscopy}, series = {Optics Express}, volume = {21}, journal = {Optics Express}, number = {6}, publisher = {Optica}, address = {Washington, DC}, issn = {1094-4087}, doi = {10.1364/OE.21.006764}, pages = {6764 -- 6776}, year = {2013}, language = {en} }