Publications Search Results

Now showing 1 - 10 of 20
  • Publication
    25th anniversary of the Berlin workshop on developmental toxicology: DevTox database update, challenges in risk assessment of developmental neurotoxicity and alternative methodologies in bone development and growth
    ( 2021)
    Marx-Stoelting, P.
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    Solano, M.D.L.M.
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    Aoyama, H.
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    Adams, R.H.
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    Bal-Price, A.
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    Buschmann, J.
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    Chahoud, I.
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    Clark, R.
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    Fang, T.
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    Fujiwara, M.
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    Gelinsky, M.
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    Grote, K.
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    Horimoto, M.
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    Bennekou, S.H.
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    Kellner, R.
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    Kuwagata, M.
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    Leist, M.
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    Lang, A.
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    Li, W.
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    Mantovani, A.
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    Makris, S.L.
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    Paumgartten, F.
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    Perron, M.
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    Sachana, M.
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    Schmitt, A.
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    Schneider, S.
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    Schönfelder, G.
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    Schulze, F.
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    Shiota, K.
    ;
    Solecki, R.
    25 years after the first Berlin Workshop on Developmental Toxicity this 10th Berlin Workshop aimed to bring together international experts from authorities, academia and industry to consider scientific, methodologic and regulatory aspects in risk assessment of developmental toxicity and to debate alternative strategies in testing developmental effects in the future. Proposals for improvement of the categorization of developmental effects were discussed as well as the update of the DevTox database as valuable tool for harmonization. The development of adverse outcome pathways relevant to developmental neurotoxicity (DNT) was debated as a fundamental improvement to guide the screening and testing for DNT using alternatives to animal methods. A further focus was the implementation of an in vitro mechanism-based battery, which can support various regulatory applications associated with the assessment of chemicals and mixtures. More interdisciplinary and translation research should be initiated to accelerate the development of new technologies to test developmental toxicity. Technologies in the pipeline are (i) high throughput imaging techniques, (ii) models for DNT screening tests, (iii) use of computer tomography for assessment of thoracolumbar supernumerary ribs in animal models, and (iv) 3D biofabrication of bone development and regeneration tissue models. In addition, increased collaboration with the medical community was suggested to improve the relevance of test results to humans and identify more clinically relevant endpoints. Finally, the participants agreed that this conference facilitated better understanding innovative approaches that can be useful for the identification of developmental health risks due to exposure to chemical substances.
  • Publication
    In silico methods - Computational alternatives to animal testing
    ( 2018)
    Lang, A.
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    Volkamer, A.
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    Behm, L.
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    Röblitz, S.
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    Ehrig, R.
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    Schneider, M.
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    Geris, L.
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    Wichard, J.
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    Buttgereit, F.
  • Publication
    Metal/FRP connection module - A powder metallurgical approach
    ( 2015)
    Hutsch, T.
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    Lang, A.
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    Schubert, T.
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    Schiebel, P.
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    Christ, M.
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    Weißgärber, T.
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    Kieback, B.
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    Herrmann, A.
    The Development of Fiber Reinforced Plastics (FRP) offers a great opportunity for applications in automobile industry, aeronautics and consumer goods to achieve light weight structures. However, the connection technology between FRP and mainly metallic based structures is the key to use the full potential of the FRP. Out of this motivation recent developments address this aspect. Using the powder metallurgical approach to generate a metal/ FRP connection module by spark plasma sintering a great variety is possible by integration of different metal and/ or fiber components. In this work aluminum and stainless steel was chosen for the upper and lower metallic side. The fibers integrated into the metal were glass, basalt and carbon fiber in one layer, two layer and mixed layer configuration. To connect the sintered module to greater CF weaves an infiltration process with a room temperature curing resin was used in a modified vacuum infusion (MVI) setup. In not optimized configuration the shear test after infiltration indicated an initial value for module shear strength above 20 MPa which can be enhanced in future developments by optimized armor between the upper and lower metal side and the number of integrated fiber layers of the connection module. A model is predicted to calculate the module shear strength in sintered state by multiplication of the armor area with the shear strength of the armor material. First experiments additionally show the possibility to weld the connection module directly to metallic structures.
  • Publication
    Joining of aluminum and CFRP parts using titanium foils as transition elements
    ( 2014)
    Woizeschke, P.
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    Schumacher, J.
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    Specht, U.
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    Lang, A.
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    Vollertsen, F.
    Multi-material design allows the adaptation of structural properties to specific local requirements. Especially, aluminum alloys (Al) and carbon fiber reinforced plastics (CFRP) are materials of great interest for the automotive and aircraft industries. Thus, the research group "Schwarz-Silber" (DFG FOR1224) located at the University of Bremen aims to develop and investigate novel concepts for advanced Al-CFRP joining techniques using transition structures. In the "foil concept" titanium (Ti) foils are used as transition elements. The Ti-CFRP sub-joint is generated by replacing CFRP layers stepwise with the titanium foils. Titanium surfaces are pre-modified by using a pulsed laser treatment to increase the interlaminar shear strength. The pure titanium side of the hybrid Ti-CFRP laminate is joined to an aluminum sheet using a heat conduction laser beam process. In this paper, the manufacturing process of such Al-Ti-CFRP joints is presented. Properties of these specimens are discussed with respect to their behavior in tensile tests. Different failure modes have been observed. A tensile strength of 96 N/mm² in average of all observed failure locations has been calculated by normalizing the maximum tensile force to the cross-sectional area of the aluminum base sheet.
  • Publication
    Integration of gass fibre structures in aluminium cast parts for CFRP aluminium transition structures
    ( 2013)
    Clausen, J.
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    Specht, U.
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    Busse, M.
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    Lang, A.
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    Sanders, J.
    Weight saving is targeted in different industrial sectors. This leads to increasing numbers of applications of fibre composites for primary structural components. In consequence the use of composites made of FRP and metals are highly attractive. Within the investigations of the researcher group 'Schwarz-Silber' (FOR 1224) funded by the DFG (Deutsche Forschungsgemeinschaft) new interface structures for advanced FRP-aluminium hybrid structures are currently investigated. By these combinations a weight reduction by a factor of two is aspired compared to conventional riveting connections. This paper focuses the research in the so called fibre concept and the integration of glass fibre structures in aluminium parts via casting technologies. During the investigations of integral CFRP-Al compounds, glass fibre structures were integrated directly into near-net-shaped castings. The challenges are the infiltration of fibre structures with aluminium and a reproducible positioning in the cast part. In this study the high pressure die casting and the Lost Foam casting processes were examined.
  • Publication
    Integration of glass fibre structures in aluminium cast parts for CFRP aluminium transition structures
    ( 2013)
    Clausen, J.
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    Specht, U.
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    Busse, M.
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    Lang, A.
    ;
    Sanders, J.
    Weight saving is targeted in different industrial sectors. This leads to increasing numbers of applications of fibre composites for primary structural components. In consequence the use of composites made of FRP and metals are highly attractive. Within the investigations of the researcher group 'Schwarz-Silber' (FOR 1224) funded by the DFG (Deutsche Forschungsgemeinschaft) new interface structures for advanced FRP-aluminium hybrid structures are currently investigated. By these combinations a weight reduction by a factor of two is aspired compared to conventional riveting connections. This paper focuses the research in the so called fibre concept and the integration of glass fibre structures in aluminium parts via casting technologies. During the investigations of integral CFRP-Al compounds, glass fibre structures were integrated directly into near-net-shaped castings. The challenges are the infiltration of fibre structures with aluminium and a reproducible positioning in the cast part. In this study the high pressure die casting and the Lost Foam casting processes were examined.
  • Publication
    Fertigung von werkstoffgerechten Verbindungen aus CFK und Aluminium
    ( 2012)
    Hehl, A. von
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    Lang, A.
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    Wottschel, V.
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    Specht, U.
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    Clausen, J.
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    Bitykov, V.
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    Schumacher, J.
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    Schimanski, K.
    Moderne Leichtbauwerkstoffe erlangen eine immer größere Bedeutung sowohl im Flugzeug- als auch im Automobilbau. Um unterschiedliche Werkstoffe örtlich optimal ausnutzen zu können, geht der moderne Werkstoffleichtbau zunehmend in Richtung Mischbauweisen. Hierbei sind vor allem Mischbauweisen aus CFK und Aluminium von besonderem Interesse. Zur Realisierung möglichst schlanker und integraler Strukturen sind jedoch neue werkstoffgerechte Verbindungstechniken notwendig. Die von der DFG geförderte Forschergruppe "Schwarz-Silber" (FOR1224) hat sich zum Ziel gesetzt, unterschiedliche Konzepte an Übergangsstrukturen für CFK-Aluminium-Verbindungen zu entwickeln und hinsichtlich der Herstellbarkeit und Belastbarkeit zu untersuchen. Ergebnisse der laufenden Forschungsphase sind Gegenstand dieses Beitrages.
  • Publication
    Entwicklung von Beschichtungsstrategien
    ( 2010)
    Krause, G.
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    Kraft, T.
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    Wonisch, A.
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    Meier, S.
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    Gemetz, F.
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    Weber, R.
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    Schwanke, D.
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    Lang, A.
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    Pohlner, J.
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    Pönisch, C.
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    Geng, J.
  • Publication
    Entwicklung und Anwendung numerischer Simulationsmethoden für den Siebdruck
    ( 2010)
    Krause, G.
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    Kraft, T.
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    Wonisch, A.
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    Meier, S.
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    Gemetz, F.
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    Weber, R.
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    Schwanke, D.
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    Lang, A.
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    Pohlner, J.
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    Pönisch, C.
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    Geng, J.
  • Publication
    Advanced audio watermarking benchmarking
    ( 2004)
    Dittmann, J.
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    Steinebach, M.
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    Lang, A.
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    Zmudizinski, S.
    Digital watermarking is envisaged as a potential technology for copyright protection and manipulation recognition. A key issue in the usage of robust watermarking is the evaluation of robustness and security. StirMark Benchmarking has been taken to set a benchmarking suite for audio watermarking in addition to existing still image evaluation solutions. In particular we give an overview of recent advancements and actual questions in robustness and transparency evaluations, in complexity and performance issues, in security and capacity questions. Further more we introduce benchmarking for content-fragile watermarking by summarizing design aspects and concluding essential benchmarking requirements.