TY - JOUR A1 - Pieper, Martin A1 - Klein, Peter T1 - Application of simple, periodic homogenization techniques to non-linear heat conduction problems in non-periodic, porous media JF - Heat mass transfer N2 - Often, detailed simulations of heat conduction in complicated, porous media have large runtimes. Then homogenization is a powerful tool to speed up the calculations by preserving accurate solutions at the same time. Unfortunately real structures are generally non-periodic, which requires unpractical, complicated homogenization techniques. We demonstrate in this paper, that the application of simple, periodic techniques to realistic media, that are just close to periodic, gives accurate, approximative solutions. In order to obtain effective parameters for the homogenized heat equation, we have to solve a so called “cell problem”. In contrast to periodic structures it is not trivial to determine a suitable unit cell, which represents a non-periodic media. To overcome this problem, we give a rule of thumb on how to choose a good cell. Finally we demonstrate the efficiency of our method for virtually generated foams as well as real foams and compare these results to periodic structures. Y1 - 2012 U6 - http://dx.doi.org/10.1007/s00231-011-0879-4 SN - 0947-7411 VL - 48 IS - 2 SP - 291 EP - 300 PB - Springer CY - Berlin ER - TY - JOUR A1 - Helsper, Christoph A1 - Nießner, R. A1 - Rönicke, G. T1 - Application of a Multistep Condensation Nuclei Counter as a Detector for Particle Surface Composition / Nießner, R.; Helsper, C.; Rönicke, G. JF - Aerosols : science, technology, and industr. applications of airborne particles ; proceedings of the 1. Internat. Aerosol Conference held Sept. 17-21, 1984, Minneapolis, Minn., U.S.A / ed.: Benjamin Y. H. Liu Y1 - 1984 SN - 0444009477 N1 - International Aerosol Conference ; (1, 1984, Minneapolis, Minn.) SP - 63 EP - 66 PB - Elsevier CY - New York [u.a.] ER - TY - JOUR A1 - Helsper, Christoph A1 - Nießner, R. T1 - Application of a Multistep Condensation Nuclei Counter as a Detector for Particle Surface Composition / Nießner, R. ; Helsper, C. JF - Journal of Aerosol Science. 16 (1985), H. 3 Y1 - 1985 SN - 0021-8502 SP - 201 EP - 209 ER - TY - JOUR A1 - Förster, Arnold A1 - Darmo, J. A1 - Dubecky, F. A1 - Kordos, P. T1 - Annealing effect on concentration of EL6-like deep-level state in low-temperature-grown molecular beam epitaxial GaAs. Darmo, J.; Dubecky, F.; Kordos, P.; Förster, A. JF - Applied Physics Letters. 72 (1998), H. 5 Y1 - 1998 SN - 1077-3118 SP - 590 EP - 592 ER - TY - JOUR A1 - Förster, Arnold A1 - Darmo, J. A1 - Dubecký, F. A1 - Kordos, P. T1 - Annealing characteristics of native defects in low-temperature-grown MBE GaAs / J. Darmo ; F. Dubecky ; P. Kordos ; A. Förster JF - Semiconducting and insulating materials 1996 : proceedings of the 9th Conference on Semiconducting and Insulating Materials (SIMC '9), April 29 - May 3, 1996, Toulouse, France / [IEEE] Y1 - 1996 SN - 0-7803-3095-1 N1 - 2. ISBN: 0-7803-3179-6 ; Conference on Semiconducting and Insulating Materials <9, 1996, Toulouse> ; Institute of Electrical and Electronics Engineers ; IEEE Cat. No.96CH35881 SP - 67 EP - ff. CY - Piscataway, NJ [u.a.] ER - TY - JOUR A1 - Barsov, S. A1 - Bechstedt, U. A1 - Hardt, Arno T1 - ANKE, a new facility for medium energy hadron physics at COSY-Jülich / S. Barsov [u.a.] JF - Nuclear instruments and methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. Vol. 462, iss. 3 Y1 - 2001 SN - 0167-5087 (Print) ; 0168-9002 (E-journal) SP - 364 EP - 381 ER - TY - CHAP A1 - Breitbach, Gerd A1 - Alexopoulos, Spiros A1 - May, Martin A1 - Teixeira Boura, Cristiano José A1 - Herrmann, Ulf T1 - Analysis of volumetric solar radiation absorbers made of wire meshes T2 - AIP Conference Proceedings Y1 - 2019 U6 - http://dx.doi.org/10.1063/1.5117521 SN - 0094243X VL - 2126 SP - 030009-1 EP - 030009-6 ER - TY - JOUR A1 - Butenweg, Christoph A1 - Rosin, Julia A1 - Holler, Stefan T1 - Analysis of cylindrical granular material silos under seismic excitation JF - Buildings N2 - Silos generally work as storage structures between supply and demand for various goods, and their structural safety has long been of interest to the civil engineering profession. This is especially true for dynamically loaded silos, e.g., in case of seismic excitation. Particularly thin-walled cylindrical silos are highly vulnerable to seismic induced pressures, which can cause critical buckling phenomena of the silo shell. The analysis of silos can be carried out in two different ways. In the first, the seismic loading is modeled through statically equivalent loads acting on the shell. Alternatively, a time history analysis might be carried out, in which nonlinear phenomena due to the filling as well as the interaction between the shell and the granular material are taken into account. The paper presents a comparison of these approaches. The model used for the nonlinear time history analysis considers the granular material by means of the intergranular strain approach for hypoplasticity theory. The interaction effects between the granular material and the shell is represented by contact elements. Additionally, soil–structure interaction effects are taken into account. KW - granular silo KW - earthquake engineering KW - hypoplasticity KW - nonlinear transient analyses Y1 - 2017 U6 - http://dx.doi.org/10.3390/buildings7030061 SN - 2075-5309 VL - 7 IS - 3 SP - 1 EP - 12 PB - MDPI CY - Basel ER - TY - CHAP A1 - Rosin, J. A1 - Mykoniou, K. A1 - Butenweg, Christoph T1 - Analysis Of Base Isolated Liquid Storage Tanks With 3D Fsi-Analysis As Well As Simplified Approaches T2 - 16th World Conference on Earthquake Engineering, 16WCEE 2017 Santiago Chile, January 9th to 13th 2017 N2 - Tanks are preferably designed, for cost-saving reasons, as circular, cylindrical, thin-walled shells. In case of seismic excitation, these constructions are highly vulnerable to stability failures. An earthquake-resistant design of rigidly supported tanks for high seismic loading demands, however, uneconomic wall thicknesses. A cost-effective alternative can be provided by base isolation systems. In this paper, a simplified seismic design procedure for base isolated tanks is introduced, by appropriately modifying the standard mechanical model for flexible, rigidly supported tanks. The non-linear behavior of conventional base isolation systems becomes an integral part of a proposed simplified process, which enables the assessment of the reduced hydrodynamic forces acting on the tank walls and the corresponding stress distribution. The impulsive and convective actions of the liquid are taken into account. The validity of this approach is evaluated by employing a non-linear fluid-structure interaction algorithm of finite element method. Special focus is placed on the boundary conditions imposed from the base isolation and the resulting hydrodynamic pressures. Both horizontal and vertical component of ground motion are considered in order to study the principal effects of the base isolation on the pressure distribution of the tank walls. The induced rocking effects associated with elastomeric bearings are discussed. The results manifest that base isolated tanks can be designed for seismic loads by means of the proposed procedure with sufficient accuracy, allowing to dispense with numerically expensive techniques. KW - liquid storage tank KW - seismic isolation KW - elastomeric bearing KW - friction pendulum bearing KW - simplified approach Y1 - 2017 N1 - Paper No 2246 SP - 1 EP - 14 PB - Chilean Association on Seismology and Earthquake Engineering (ACHISINA) ER - TY - CHAP A1 - Gedle, Yibekal A1 - Schmitz, Mark A1 - Gielen, Hans A1 - Schmitz, Pascal A1 - Herrmann, Ulf A1 - Teixeira Boura, Cristiano José A1 - Mahdi, Zahra A1 - Caminos, Ricardo Alexander Chico A1 - Dersch, Jürgen T1 - Analysis of an integrated CSP-PV hybrid power plant T2 - SolarPACES 2020 N2 - In the past, CSP and PV have been seen as competing technologies. Despite massive reductions in the electricity generation costs of CSP plants, PV power generation is - at least during sunshine hours - significantly cheaper. If electricity is required not only during the daytime, but around the clock, CSP with its inherent thermal energy storage gets an advantage in terms of LEC. There are a few examples of projects in which CSP plants and PV plants have been co-located, meaning that they feed into the same grid connection point and ideally optimize their operation strategy to yield an overall benefit. In the past eight years, TSK Flagsol has developed a plant concept, which merges both solar technologies into one highly Integrated CSP-PV-Hybrid (ICPH) power plant. Here, unlike in simply co-located concepts, as analyzed e.g. in [1] – [4], excess PV power that would have to be dumped is used in electric molten salt heaters to increase the storage temperature, improving storage and conversion efficiency. The authors demonstrate the electricity cost sensitivity to subsystem sizing for various market scenarios, and compare the resulting optimized ICPH plants with co-located hybrid plants. Independent of the three feed-in tariffs that have been assumed, the ICPH plant shows an electricity cost advantage of almost 20% while maintaining a high degree of flexibility in power dispatch as it is characteristic for CSP power plants. As all components of such an innovative concept are well proven, the system is ready for commercial market implementation. A first project is already contracted and in early engineering execution. KW - Hybrid energy system KW - Power plants KW - Electricity generation KW - Energy storage KW - Associated liquids Y1 - 2022 SN - 978-0-7354-4195-8 U6 - http://dx.doi.org/10.1063/5.0086236 SN - 1551-7616 (online) SN - 0094-243X (print) N1 - 26th International Conference on Concentrating Solar Power and Chemical Energy Systems 28 September–2 October 2020 Freiburg, Germany IS - 2445 / 1 PB - AIP conference proceedings / American Institute of Physics CY - Melville, NY ER -