@article{LuftBremenLuft2023, author = {Luft, Angela and Bremen, Sebastian and Luft, Nils}, title = {A cost/benefit and flexibility evaluation framework for additive technologies in strategic factory planning}, series = {Processes}, volume = {11}, journal = {Processes}, number = {7}, publisher = {MDPI}, address = {Basel}, issn = {2227-9717}, doi = {10.3390/pr11071968}, pages = {Artikel 1968}, year = {2023}, abstract = {There is a growing demand for more flexibility in manufacturing to counter the volatility and unpredictability of the markets and provide more individualization for customers. However, the design and implementation of flexibility within manufacturing systems are costly and only economically viable if applicable to actual demand fluctuations. To this end, companies are considering additive manufacturing (AM) to make production more flexible. This paper develops a conceptual model for the impact quantification of AM on volume and mix flexibility within production systems in the early stages of the factory-planning process. Together with the model, an application guideline is presented to help planners with the flexibility quantification and the factory design process. Following the development of the model and guideline, a case study is presented to indicate the potential impact additive technologies can have on manufacturing flexibility Within the case study, various scenarios with different production system configurations and production programs are analyzed, and the impact of the additive technologies on volume and mix flexibility is calculated. This work will allow factory planners to determine the potential impacts of AM on manufacturing flexibility in an early planning stage and design their production systems accordingly.}, language = {en} } @article{AbbasHedwigBalcetal.2023, author = {Abbas, Karim and Hedwig, Lukas and Balc, Nicolae and Bremen, Sebastian}, title = {Advanced FFF of PEEK: Infill strategies and material characteristics for rapid tooling}, series = {Polymers}, volume = {2023}, journal = {Polymers}, number = {15}, publisher = {MDPI}, address = {Basel}, doi = {10.3390/polym15214293}, pages = {Artikel 4293}, year = {2023}, abstract = {Traditional vulcanization mold manufacturing is complex, costly, and under pressure due to shorter product lifecycles and diverse variations. Additive manufacturing using Fused Filament Fabrication and high-performance polymers like PEEK offer a promising future in this industry. This study assesses the compressive strength of various infill structures (honeycomb, grid, triangle, cubic, and gyroid) when considering two distinct build directions (Z, XY) to enhance PEEK's economic and resource efficiency in rapid tooling. A comparison with PETG samples shows the behavior of the infill strategies. Additionally, a proof of concept illustrates the application of a PEEK mold in vulcanization. A peak compressive strength of 135.6 MPa was attained in specimens that were 100\% solid and subjected to thermal post-treatment. This corresponds to a 20\% strength improvement in the Z direction. In terms of time and mechanical properties, the anisotropic grid and isotropic cubic infill have emerged for use in rapid tooling. Furthermore, the study highlights that reducing the layer thickness from 0.15 mm to 0.1 mm can result in a 15\% strength increase. The study unveils the successful utilization of a room-temperature FFF-printed PEEK mold in vulcanization injection molding. The parameters and infill strategies identified in this research enable the resource-efficient FFF printing of PEEK without compromising its strength properties. Using PEEK in rapid tooling allows a cost reduction of up to 70\% in tool production.}, language = {en} } @incollection{AtmaneHirechKassmietal.2020, author = {Atmane, Ilias and Hirech, Kamal and Kassmi, K. and Mahdi, Zahra and Alexopoulos, Spiros and Schwarzer, Klemens and Chayeb, H. and Bachiri, N.}, title = {Design and realization of a pilot solar desalination plant in Douar El Hamri in the province of Berkane (Morocco)}, series = {Sustainable entrepreneurship, renewable energy-based projects, and digitalization}, booktitle = {Sustainable entrepreneurship, renewable energy-based projects, and digitalization}, editor = {Omrane, Amina and Kassmi, Khalil and Akram, Muhammad Wasim and Khanna, Ashish and Mostafiz, Imtiaz}, publisher = {CRC Press}, address = {Boca Raton, Fa.}, isbn = {9781000292541 (E-Book)}, pages = {18 Seiten}, year = {2020}, abstract = {Producing fresh water from saline water has become one of the most difficult challenges to overcome especially with the high demand and shortage of fresh water. In this context, as part of a collaboration with Germany, the authors propose a design and implementation of a pilot multi-stage solar desalination system (MSD), remotely controlled, at Douar Al Hamri in the rural town of Boughriba in the province of Berkane, Morocco. More specifically, they present their contribution on the remote control and supervision system, which makes the functioning of the MSD system reliable and guarantees the production of drinking water for the population of Douar. The results obtained show that the electronic cards and computer communication software implemented allow the acquisition of all electrical (currents, voltages, powers, yields), thermal (temperatures of each stage), and meteorological (irradiance and ambient temperature), remote control and maintenance (switching on, off, data transfer). By comparing with the literature carried out in the field of solar energy, the authors conclude that the MSD and electronic desalination systems realized during this work represent a contribution in terms of the reliability and durability of providing drinking water in rural and urban areas.}, language = {en} } @inproceedings{ElMoussaouiKassmiAlexopoulosetal.2021, author = {El Moussaoui, Noureddine and Kassmi, Khalil and Alexopoulos, Spiros and Schwarzer, Klemens and Chayeb, Hamid and Bachiri, Najib}, title = {Simulation studies on a new innovative design of a hybrid solar distiller MSDH alimented with a thermal and photovoltaic energy}, series = {Materialstoday: Proceedings}, volume = {45}, booktitle = {Materialstoday: Proceedings}, number = {8}, publisher = {Elsevier}, address = {Amsterdam}, issn = {2214-7853}, doi = {10.1016/j.matpr.2021.03.115}, pages = {7653 -- 7660}, year = {2021}, abstract = {In this paper, we present the structure, the simulation the operation of a multi-stage, hybrid solar desalination system (MSDH), powered by thermal and photovoltaic (PV) (MSDH) energy. The MSDH system consists of a lower basin, eight horizontal stages, a field of four flat thermal collectors with a total area of 8.4 m2, 3 Kw PV panels and solar batteries. During the day the system is heated by thermal energy, and at night by heating resistors, powered by solar batteries. These batteries are charged by the photovoltaic panels during the day. More specifically, during the day and at night, we analyse the temperature of the stages and the production of distilled water according to the solar irradiation intensity and the electric heating power, supplied by the solar batteries. The simulations were carried out in the meteorological conditions of the winter month (February 2020), presenting intensities of irradiance and ambient temperature reaching 824 W/m2 and 23 °C respectively. The results obtained show that during the day the system is heated by the thermal collectors, the temperature of the stages and the quantity of water produced reach 80 °C and 30 Kg respectively. At night, from 6p.m. the system is heated by the electric energy stored in the batteries, the temperature of the stages and the quantity of water produced reach respectively 90 °C and 104 Kg for an electric heating power of 2 Kw. Moreover, when the electric power varies from 1 Kw to 3 Kw the quantity of water produced varies from 92 Kg to 134 Kg. The analysis of these results and their comparison with conventional solar thermal desalination systems shows a clear improvement both in the heating of the stages, by 10\%, and in the quantity of water produced by a factor of 3.}, language = {en} } @article{AbbasBalcBremenetal.2022, author = {Abbas, Karim and Balc, Nicolae and Bremen, Sebastian and Skupin, Marco}, title = {Crystallization and aging behavior of polyetheretherketone PEEK within rapid tooling and rubber molding}, series = {Journal of Manufacturing and Materials Processing}, volume = {6}, journal = {Journal of Manufacturing and Materials Processing}, number = {5}, publisher = {MDPI}, address = {Basel}, issn = {2504-4494}, doi = {10.3390/jmmp6050093}, pages = {1 -- 12}, year = {2022}, abstract = {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.}, language = {en} } @article{DachwaldSeboldtRichter2003, author = {Dachwald, Bernd and Seboldt, Wolfgang and Richter, L.}, title = {Multiple Rendezvous and Sample Return Missions to Near-Earth Asteroids Using Solar Sailcraft}, series = {Proceedings of the Fifth IAA International Conference on Low Cost Planetary Missions : 24 - 26 September 2003, ESTEC, Noordwijk, the Netherlands / [comp. by R. A. Harris]}, journal = {Proceedings of the Fifth IAA International Conference on Low Cost Planetary Missions : 24 - 26 September 2003, ESTEC, Noordwijk, the Netherlands / [comp. by R. A. Harris]}, publisher = {ESA}, address = {Noordwijk}, isbn = {92-9092-853-0}, pages = {351 -- 358}, year = {2003}, language = {en} } @article{DachwaldOhndorfSeboldt2005, author = {Dachwald, Bernd and Ohndorf, A. and Seboldt, Wolfgang}, title = {Optimierung der Lageregelung von Raumfahrzeugen mit Niedrigschubantrieb mittels evolution{\"a}rer neuronaler Regler / A. Ohndorf ; B. Dachwald ; W. Seboldt}, series = {Deutscher Luft- und Raumfahrtkongress 2005 : Friedrichshafen, 26. bis 29. September 2005, Motto: Luft- und Raumfahrt - Grenzen {\"u}berwinden, Horizonte erweitern / Deutsche Gesellschaft f{\"u}r Luft- und Raumfahrt - Lilienthal-Oberth e.V. (DGLR). [Red.: Peter Brandt (verantwortlich)]. Bd. 3. - (Jahrbuch ... der Deutschen Gesellschaft f{\"u}r Luft- und Raumfahrt}, journal = {Deutscher Luft- und Raumfahrtkongress 2005 : Friedrichshafen, 26. bis 29. September 2005, Motto: Luft- und Raumfahrt - Grenzen {\"u}berwinden, Horizonte erweitern / Deutsche Gesellschaft f{\"u}r Luft- und Raumfahrt - Lilienthal-Oberth e.V. (DGLR). [Red.: Peter Brandt (verantwortlich)]. Bd. 3. - (Jahrbuch ... der Deutschen Gesellschaft f{\"u}r Luft- und Raumfahrt}, publisher = {DGLR}, address = {Bonn}, pages = {1971 -- 1978}, year = {2005}, language = {de} } @article{DachwaldSeboldt2005, author = {Dachwald, Bernd and Seboldt, Wolfgang}, title = {Solar Sails for Near- and Medium-Term Scientific Deep Space Missions / W. Sebolt ; B. Dachwald}, series = {In-space propulsion : edited book of proceedings of the 10-IWCP, the 10th International Workshop on Combustion and Propulsion held in Lerici, La Spezia, Italy, 21-25 September 2003 / [ed.: Luigi T. DeLuca]}, journal = {In-space propulsion : edited book of proceedings of the 10-IWCP, the 10th International Workshop on Combustion and Propulsion held in Lerici, La Spezia, Italy, 21-25 September 2003 / [ed.: Luigi T. DeLuca]}, publisher = {SP Lab, Politecnico di Milano}, address = {Milano}, pages = {getr. Z{\"a}hlung . Ill.}, year = {2005}, language = {en} } @article{DachwaldSeboldt2008, author = {Dachwald, Bernd and Seboldt, Wolfgang}, title = {Solar Sails — Propellantless Propulsion for Near- and Medium-Term Deep-Space Missions / W. Seboldt ; B. Dachwald}, series = {Advanced Propulsion Systems and Technologies, Today to 2020 / Claudio Bruno (ed.) ... - (Progress in Astronautics and Aeronautics Series ; 223)}, journal = {Advanced Propulsion Systems and Technologies, Today to 2020 / Claudio Bruno (ed.) ... - (Progress in Astronautics and Aeronautics Series ; 223)}, publisher = {AIAA}, address = {Reston, Va.}, isbn = {978-1-56347-929-8}, pages = {460 S.}, year = {2008}, language = {en} } @article{LeipoldFichtnerHeberetal.2006, author = {Leipold, M. and Fichtner, H. and Heber, B. and Groepper, P. and Lascar, S. and Burger, F. and Eiden, M. and Niederstadt, T. and Sickinger, C. and Herbeck, L. and Dachwald, Bernd and Seboldt, Wolfgang}, title = {Heliopause Explorer - A Sailcraft Mission to the Outer Boundaries of the Solar System}, series = {Acta Astronautica. 59 (2006), H. 8-11}, journal = {Acta Astronautica. 59 (2006), H. 8-11}, isbn = {0094-5765}, pages = {786 -- 796}, year = {2006}, language = {en} } @article{DachwaldSeboldtLaemmerzahl2008, author = {Dachwald, Bernd and Seboldt, Wolfgang and L{\"a}mmerzahl, W.}, title = {Solar Sail Propulsion: An Enabling Technology for Fundamental Physics Missions}, series = {Lasers, Clocks and Drag Free Control : Exploration of Relativistic Gravity in Space / by Hansj{\"o}rg Dittus ..., eds. - ( Astrophysics and Space Science Library ; 349)}, journal = {Lasers, Clocks and Drag Free Control : Exploration of Relativistic Gravity in Space / by Hansj{\"o}rg Dittus ..., eds. - ( Astrophysics and Space Science Library ; 349)}, publisher = {Springer}, address = {Berlin [u.a.]}, isbn = {978-3-540-34376-9}, pages = {379 -- 398}, year = {2008}, language = {en} } @article{DachwaldSeboldtRichter2006, author = {Dachwald, Bernd and Seboldt, Wolfgang and Richter, L.}, title = {Multiple rendezvous and sample return missions to near-Earth objects using solar sailcraft / Dachwald, B. ; Seboldt, W. ; Richter, L.}, series = {Acta Astronautica. 59 (2006), H. 8-11}, journal = {Acta Astronautica. 59 (2006), H. 8-11}, isbn = {0094-5765}, pages = {768 -- 776}, year = {2006}, language = {en} } @article{DachwaldSeboldt2005, author = {Dachwald, Bernd and Seboldt, Wolfgang}, title = {Multiple Near-Earth Asteroid Rendezvous and Sample Return Using First Generation Solar Sailcraft}, series = {Acta Astronautica. 57 (2005), H. 11}, journal = {Acta Astronautica. 57 (2005), H. 11}, isbn = {0094-5765}, pages = {864 -- 875}, year = {2005}, language = {en} } @article{DachwaldSeboldtLoebetal.2008, author = {Dachwald, Bernd and Seboldt, Wolfgang and Loeb, H. W. and Schartner, Karl-Heinz}, title = {Main Belt Asteroid Sample Return Mission Using Solar Electric Propulsion}, series = {Acta Astronautica. 63 (2008), H. 1-4}, journal = {Acta Astronautica. 63 (2008), H. 1-4}, isbn = {0094-5765}, pages = {91 -- 101}, year = {2008}, language = {en} }