TY - INPR A1 - Ringers, Christa A1 - Bialonski, Stephan A1 - Solovev, Anton A1 - Hansen, Jan N. A1 - Ege, Mert A1 - Friedrich, Benjamin M. A1 - Jurisch-Yaksi, Nathalie T1 - Preprint: Local synchronization of cilia and tissue-scale cilia alignment are sufficient for global metachronal waves T2 - bioRxiv N2 - Motile cilia are hair-like cell extensions present in multiple organs of the body. How cilia coordinate their regular beat in multiciliated epithelia to move fluids remains insufficiently understood, particularly due to lack of rigorous quantification. We combine here experiments, novel analysis tools, and theory to address this knowledge gap. We investigate collective dynamics of cilia in the zebrafish nose, due to its conserved properties with other ciliated tissues and its superior accessibility for non-invasive imaging. We revealed that cilia are synchronized only locally and that the size of local synchronization domains increases with the viscosity of the surrounding medium. Despite the fact that synchronization is local only, we observed global patterns of traveling metachronal waves across the multiciliated epithelium. Intriguingly, these global wave direction patterns are conserved across individual fish, but different for left and right nose, unveiling a chiral asymmetry of metachronal coordination. To understand the implications of synchronization for fluid pumping, we used a computational model of a regular array of cilia. We found that local metachronal synchronization prevents steric collisions and improves fluid pumping in dense cilia carpets, but hardly affects the direction of fluid flow. In conclusion, we show that local synchronization together with tissue-scale cilia alignment are sufficient to generate metachronal wave patterns in multiciliated epithelia, which enhance their physiological function of fluid pumping. Y1 - 2021 U6 - https://doi.org/10.1101/2021.11.23.469646 N1 - Veröffentlicht in eLife 12:e77701 (https://doi.org/10.7554/eLife.77701). ER - TY - JOUR A1 - Abbas, Karim A1 - Balc, Nicolae A1 - Bremen, Sebastian A1 - Skupin, Marco T1 - Crystallization and aging behavior of polyetheretherketone PEEK within rapid tooling and rubber molding JF - Journal of Manufacturing and Materials Processing N2 - In times of short product life cycles, additive manufacturing and rapid tooling are important methods to make tool development and manufacturing more efficient. High-performance polymers are the key to mold production for prototypes and small series. However, the high temperatures during vulcanization injection molding cause thermal aging and can impair service life. The extent to which the thermal stress over the entire process chain stresses the material and whether it leads to irreversible material aging is evaluated. To this end, a mold made of PEEK is fabricated using fused filament fabrication and examined for its potential application. The mold is heated to 200 ◦C, filled with rubber, and cured. A differential scanning calorimetry analysis of each process step illustrates the crystallization behavior and first indicates the material resistance. It shows distinct cold crystallization regions at a build chamber temperature of 90 ◦C. At an ambient temperature above Tg, crystallization of 30% is achieved, and cold crystallization no longer occurs. Additional tensile tests show a decrease in tensile strength after ten days of thermal aging. The steady decrease in recrystallization temperature indicates degradation of the additives. However, the tensile tests reveal steady embrittlement of the material due to increasing crosslinking. KW - additive manufacturing KW - fused filament fabrication KW - crystallization KW - polyetheretherketone KW - rapid tooling Y1 - 2022 U6 - https://doi.org/10.3390/jmmp6050093 SN - 2504-4494 N1 - The article belongs to the Special Issue Advances in Injection Molding: Process, Materials and Applications VL - 6 IS - 5 SP - 1 EP - 12 PB - MDPI CY - Basel ER - TY - CHAP A1 - Rosin, Julia A1 - Kubalski, Thomas A1 - Butenweg, Christoph T1 - Seismic Design of cylindrical liquid storage tanks T2 - Seismic design of industrial facilities : proceedings of the International Conference on Seismic Design of Industrial Facilities (SeDIF-Conference) ; [Aachen, 26. - 27. September 2013] / Chair of Structural Statics and Dynamics, RWTH Aachen. Sven Klinkel ..., ed. Y1 - 2014 SN - 978-3-658-02810-7 (E-Book) ; 978-3-658-02809-1 (Print) U6 - https://doi.org/10.1007/978-3-658-02810-7_36 SP - 429 EP - 440 PB - Springer Vieweg CY - Wiesbaden ER - TY - CHAP A1 - Altay, Okyay A1 - Butenweg, Christoph A1 - Klinkel, Sven T1 - Vibration mitigation of wind turbine towers by a new semiactive Tuned Liquid Column Damper T2 - 6. Word Congress on Structural Control and Monitoring, 15 - 17 July, 2014 Barcelona,Spain Y1 - 2014 ER - TY - CHAP A1 - Butenweg, Christoph A1 - Bursi, Oreste S. A1 - Nardin, Chiara A1 - Lanese, Igor A1 - Pavese, Alberto A1 - Marinković, Marko A1 - Paolacci, Fabrizio A1 - Quinci, Gianluca T1 - Experimental investigation on the seismic performance of a multi-component system for major-hazard industrial facilities T2 - Conference Proceedings: Pressure Vessels & Piping Conference Vol.5 N2 - Past earthquakes demonstrated the high vulnerability of industrial facilities equipped with complex process technologies leading to serious damage of the process equipment and multiple and simultaneous release of hazardous substances in industrial facilities. Nevertheless, the design of industrial plants is inadequately described in recent codes and guidelines, as they do not consider the dynamic interaction between the structure and the installations and thus the effect of seismic response of the installations on the response of the structure and vice versa. The current code-based approach for the seismic design of industrial facilities is considered not enough for ensure proper safety conditions against exceptional event entailing loss of content and related consequences. Accordingly, SPIF project (Seismic Performance of Multi-Component Systems in Special Risk Industrial Facilities) was proposed within the framework of the European H2020 - SERA funding scheme (Seismology and Earthquake Engineering Research Infrastructure Alliance for Europe). The objective of the SPIF project is the investigation of the seismic behaviour of a representative industrial structure equipped with complex process technology by means of shaking table tests. The test structure is a three-story moment resisting steel frame with vertical and horizontal vessels and cabinets, arranged on the three levels and connected by pipes. The dynamic behaviour of the test structure and of its relative several installations is investigated. Furthermore, both process components and primary structure interactions are considered and analyzed. Several PGA-scaled artificial ground motions are applied to study the seismic response at different levels. After each test, dynamic identification measurements are carried out to characterize the system condition. The contribution presents the experimental setup of the investigated structure and installations, selected measurement data and describes the obtained damage. Furthermore, important findings for the definition of performance limits, the effectiveness of floor response spectra in industrial facilities will be presented and discussed. KW - industrial facilities KW - piping KW - installations KW - seismic loading KW - earthquakes Y1 - 2021 SN - 9780791885352 U6 - https://doi.org/10.1115/PVP2021-61696 N1 - ASME 2021 Pressure Vessels & Piping Conference, July 13–15, 2021, Virtual, Online PB - American Society of Mechanical Engineers (ASME) CY - New York ER - TY - CHAP A1 - Bialonski, Stephan T1 - Are interaction clusters in epileptic networks predictive of seizures? T2 - Epilepsy: The Intersection of Neurosciences, Biology, Mathematics, Engineering, and Physics Y1 - 2016 SN - 978-143983886-0 SP - 349 EP - 355 PB - CRC Press ER - TY - JOUR A1 - Funke, Harald A1 - Beckmann, Nils T1 - Flexible fuel operation of a Dry-Low-NOx Micromix Combustor with Variable Hydrogen Methane Mixture JF - International Journal of Gas Turbine, Propulsion and Power Systems N2 - 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 Y1 - 2022 SN - 1882-5079 VL - 13 IS - 2 SP - 1 EP - 7 ER - TY - JOUR A1 - Edip, K. A1 - Sesov, V. A1 - Butenweg, Christoph A1 - Bojadjieva, J. T1 - Development of coupled numerical model for simulation of multiphase soil JF - Computers and Geotechnics N2 - In this paper, a coupled multiphase model considering both non-linearities of water retention curves and solid state modeling is proposed. The solid displacements and the pressures of both water and air phases are unknowns of the proposed model. The finite element method is used to solve the governing differential equations. The proposed method is demonstrated through simulation of seepage test and partially consolidation problem. Then, implementation of the model is done by using hypoplasticity for the solid phase and analyzing the fully saturated triaxial experiments. In integration of the constitutive law error controlling is improved and comparisons done accordingly. In this work, the advantages and limitations of the numerical model are discussed. Y1 - 2018 U6 - https://doi.org/10.1016/j.compgeo.2017.08.016 SN - 0266-352X VL - 96 SP - 118 EP - 131 PB - Elsevier CY - Amsterdam ER - TY - CHAP A1 - Funke, Harald A1 - Beckmann, Nils T1 - Flexible Fuel Operation of a Dry-Low-Nox Micromix Combustor with Variable Hydrogen Methane Mixtures T2 - Proceedings of International Gas Turbine Congress 2019 Tokyo, November 17-22, 2019, Tokyo, Japan Y1 - 2019 SN - 978-4-89111-010-9 N1 - IGTC-2019-013 ER - TY - CHAP A1 - Funke, Harald A1 - Beckmann, Nils A1 - Keinz, Jan A1 - Horikawa, Atsushi T1 - 30 years of dry low NOx micromix combustor research for hydrogen-rich fuels: an overview of past and present activities T2 - Conference Proceedings Turbo Expo: Power for Land, Sea and Air, Volume 4B: Combustion, Fuels, and Emissions N2 - 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. KW - Micromix KW - Hydrogen KW - Fuel-flexibility KW - NOx KW - Emissions Y1 - 2021 SN - 978-0-7918-8413-3 U6 - https://doi.org/10.1115/GT2020-16328 N1 - ASME Turbo Expo 2020: Turbomachinery Technical Conference and Exposition September 21–25, 2020, Virtual, Online N1 - Paper No. GT2020-16328, V04BT04A069 PB - ASME CY - New York, NY ER -