@article{PieperKlein2011, author = {Pieper, Martin and Klein, Peter}, title = {A simple and accurate numerical network flow model for bionic micro heat exchangers}, series = {Heat mass transfer}, volume = {47}, journal = {Heat mass transfer}, number = {5}, publisher = {Springer}, address = {Berlin}, isbn = {0947-7411}, pages = {491 -- 503}, year = {2011}, language = {en} } @article{PieperKlein2012, author = {Pieper, Martin and Klein, Peter}, title = {Application of simple, periodic homogenization techniques to non-linear heat conduction problems in non-periodic, porous media}, series = {Heat mass transfer}, volume = {48}, journal = {Heat mass transfer}, number = {2}, publisher = {Springer}, address = {Berlin}, issn = {0947-7411}, doi = {10.1007/s00231-011-0879-4}, pages = {291 -- 300}, year = {2012}, abstract = {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.}, language = {en} } @inproceedings{StollenwerkRiekeDahmenetal.2016, author = {Stollenwerk, Dominik and Rieke, C. and Dahmen, Markus and Pieper, Martin}, title = {Biogas Production Modelling : A Control System Engineering Approach}, series = {IOP Conference Series: Earth and Environmental Science. Bd. 32}, booktitle = {IOP Conference Series: Earth and Environmental Science. Bd. 32}, issn = {1755-1315}, doi = {10.1088/1755-1315/32/1/012008}, pages = {012008/1 -- 012008/4}, year = {2016}, language = {en} } @article{EweKleinPieperetal.2009, author = {Ewe, Hendrik and Klein, Peter and Pieper, Martin and F{\"u}ldner, G.}, title = {Heat conductivity in sintered aluminium fibers}, series = {Cellular metals for structural and functional applications : CELLMET 2008 ; proceedings of the International Symposium on Cellular Metals for Structural and Functional Applications held October 8 - 10, 2008 in Dresden, Germany / ed. by G{\"u}nter Stephani}, journal = {Cellular metals for structural and functional applications : CELLMET 2008 ; proceedings of the International Symposium on Cellular Metals for Structural and Functional Applications held October 8 - 10, 2008 in Dresden, Germany / ed. by G{\"u}nter Stephani}, publisher = {Fraunhofer IFAM}, address = {Dresden}, pages = {187 -- 193}, year = {2009}, language = {en} } @article{AlebouyehSamamiPieperBreitbachetal.2014, author = {Alebouyeh Samami, Behzad and Pieper, Martin and Breitbach, Gerd and Hodapp, Josef}, title = {Heat production in the windings of the stators of electric machines under stationary condition}, series = {Heat and mass transfer}, volume = {50}, journal = {Heat and mass transfer}, publisher = {Springer}, address = {Heidelberg}, issn = {0947-7411 (Print) ; 1432-1181 (E-Journal)}, doi = {10.1007/s00231-014-1371-8}, pages = {1707 -- 1716}, year = {2014}, abstract = {In electric machines due to high currents and resistive losses (joule heating) heat is produced. To avoid damages by overheating the design of effective cooling systems is required. Therefore the knowledge of heat sources and heat transfer processes is necessary. The purpose of this paper is to illustrate a good and effective calculation method for the temperature analysis based on homogenization techniques. These methods have been applied for the stator windings in a slot of an electric machine consisting of copper wires and resin. The key quantity here is an effective thermal conductivity, which characterizes the heterogeneous wire resin-arrangement inside the stator slot. To illustrate the applicability of the method, the analysis of a simplified, homogenized model is compared with the detailed analysis of temperature behavior inside a slot of an electric machine according to the heat generation. We considered here only the stationary situation. The achieved numerical results are accurate and show that the applied homogenization technique works in practice. Finally the results of simulations for the two cases, the original model of the slot and the homogenized model chosen for the slot (unit cell), are compared to experimental results.}, language = {en} } @inproceedings{NierlePieper2023, author = {Nierle, Elisabeth and Pieper, Martin}, title = {Measuring social impacts in engineering education to improve sustainability skills}, series = {European Society for Engineering Education (SEFI)}, booktitle = {European Society for Engineering Education (SEFI)}, doi = {10.21427/QPR4-0T22}, pages = {9 Seiten}, year = {2023}, abstract = {In times of social climate protection movements, such as Fridays for Future, the priorities of society, industry and higher education are currently changing. The consideration of sustainability challenges is increasing. In the context of sustainable development, social skills are crucial to achieving the United Nations Sustainable Development Goals (SDGs). In particular, the impact that educational activities have on people, communities and society is therefore coming to the fore. Research has shown that people with high levels of social competence are better able to manage stressful situations, maintain positive relationships and communicate effectively. They are also associated with better academic performance and career success. However, especially in engineering programs, the social pillar is underrepresented compared to the environmental and economic pillars. In response to these changes, higher education institutions should be more aware of their social impact - from individual forms of teaching to entire modules and degree programs. To specifically determine the potential for improvement and derive resulting change for further development, we present an initial framework for social impact measurement by transferring already established approaches from the business sector to the education sector. To demonstrate the applicability, we measure the key competencies taught in undergraduate engineering programs in Germany. The aim is to prepare the students for success in the modern world of work and their future contribution to sustainable development. Additionally, the university can include the results in its sustainability report. Our method can be applied to different teaching methods and enables their comparison.}, language = {en} } @article{RiekeStollenwerkDahmenetal.2018, author = {Rieke, Christian and Stollenwerk, Dominik and Dahmen, Markus and Pieper, Martin}, title = {Modeling and optimization of a biogas plant for a demand-driven energy supply}, series = {Energy}, volume = {145}, journal = {Energy}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0360-5442}, doi = {10.1016/j.energy.2017.12.073}, pages = {657 -- 664}, year = {2018}, abstract = {Due to the Renewable Energy Act, in Germany it is planned to increase the amount of renewable energy carriers up to 60\%. One of the main problems is the fluctuating supply of wind and solar energy. Here biogas plants provide a solution, because a demand-driven supply is possible. Before running such a plant, it is necessary to simulate and optimize the process. This paper provides a new model of a biogas plant, which is as accurate as the standard ADM1 model. The advantage compared to ADM1 is that it is based on only four parameters compared to 28. Applying this model, an optimization was installed, which allows a demand-driven supply by biogas plants. Finally the results are confirmed by several experiments and measurements with a real test plant.}, language = {en} } @article{Pieper2011, author = {Pieper, Martin}, title = {Multiobjective optimization with expensive objectives applied to a thermodynamic material design problem}, series = {Proceedings in applied mathematics and mechanics : PAMM. 11 (2011), H. 1}, journal = {Proceedings in applied mathematics and mechanics : PAMM. 11 (2011), H. 1}, publisher = {Wiley}, address = {Weinheim}, isbn = {1617-7061}, pages = {733 -- 734}, year = {2011}, language = {en} } @article{PieperIvanyshyn2008, author = {Pieper, Martin and Ivanyshyn, Olha}, title = {Nonlinear integral equations for a 3D inverse acoustic scattering problem : abstract / O. Ivanyshyn and M. Pieper}, year = {2008}, language = {en} } @article{Pieper2008, author = {Pieper, Martin}, title = {Nonlinear integral equations for an inverse electromagnetic scattering problem}, series = {Journal of Physics Conference Series. 124 (2008)}, journal = {Journal of Physics Conference Series. 124 (2008)}, isbn = {1742-6596}, year = {2008}, language = {en} }