@inproceedings{HolickyDiamantidisSykora, author = {Holicky, Milan and Diamantidis, Dimitris and S{\´y}kora, Miroslav}, title = {Economically optimum structural design}, series = {High Performance and Optimum Design of Structures and Materials III (HPSM/OPTI 2018) ; Ljubljana, Slovenia 11.07.2018 - 13.07.2018}, booktitle = {High Performance and Optimum Design of Structures and Materials III (HPSM/OPTI 2018) ; Ljubljana, Slovenia 11.07.2018 - 13.07.2018}, editor = {de Wilde, W. P. and Hern{\´a}ndez, S. and Kravanja, S.}, publisher = {WIT}, doi = {10.2495/hpsm180151}, pages = {143 -- 153}, abstract = {Codes of practice aim to assure structures have acceptable risks to the public and the minimum total costs over the working life of a design. However, current codified criteria for structural design correspond to a broad range of reliability levels, specified for dissimilar reference periods even though their recalculation for different periods is uncertain due to unknown dependence of failure events in time. In this contribution, target reliability levels are specified on the basis of probabilistic risk optimization considering the objective function as a sum of various costs including effects of time to failure and discounting. A case study presents probabilistic optimization of the roof of a stadium for 4,000 spectators and illustrates the effect of the considered input parameters. Failure consequences and relative cost of safety measure are shown to be major factors affecting the optimum reliability level. Less important factors are the discount rate and working life. Large uncertainty in failure cost estimates seems to have only a marginal effect on derived optimum reliability levels.}, language = {en} } @article{SykoraHolickyJungetal., author = {S{\´y}kora, Miroslav and Holicky, Milan and Jung, Karel and Diamantidis, Dimitris}, title = {Human safety criteria for risk-based structural design}, series = {International Journal of Safety and Security Engineering}, volume = {8}, journal = {International Journal of Safety and Security Engineering}, number = {2}, publisher = {WIT Press}, doi = {10.2495/SAFE-V8-N2-287-298}, pages = {287 -- 298}, abstract = {Risk and reliability criteria are well established in many industrial sectors such as the offshore, chemi- cal or nuclear industries. Comparative risk thresholds have been specified to allow a responsible organization or regulator to identify activities, which impose an acceptable level of risk concerning the participating individuals, or society as a whole. The scope of this contribution is to present target reliability criteria based on acceptable human safety levels. Application of theoretical principles is illustrated by examples of railway engineering structures. Initially it is shown how civil engineering structures for which human safety criteria play a role are classified according to Eurocodes. Examples include bridges, tunnels or station buildings. The general concepts for risk acceptance are then briefly reviewed, particularly in their relation to the target reliability criteria. The distinction between the two types of criteria is made: group risk and the acceptance criterion based on the Life Quality Index LQI approach introduced by ISO 2394:2015. The differences between the criteria for new and existing structures are discussed. The application is illustrated by an example of a bridge crossing an important railway line. It appears that while benefits and costs of a private stakeholder or public authority are reflected by economic optimisation, the society should define the limits for human safety to achieve uniform risks for various daily-life activities and across different industrial sectors. Keywords: group risk, human safety, individual risk, Life Quality Index, railway, risk acceptance, structure, target reliability}, language = {en} } @article{HoenickaKasparSchmidetal., author = {Hoenicka, Markus and Kaspar, Marcel and Schmid, Christof and Liebold, Andreas and Schrammel, Siegfried}, title = {Contact-free monitoring of vessel graft stiffness - proof of concept as a tool for vascular tissue engineering}, series = {Journal of tissue engineering and regenerative medicine}, volume = {11}, journal = {Journal of tissue engineering and regenerative medicine}, number = {10}, publisher = {Wiley}, doi = {10.1002/term.2186}, pages = {2828 -- 2835}, abstract = {Tissue-engineered vessel grafts have to mimic the biomechanical properties of native blood vessels. Manufacturing processes often condition grafts to adapt them to the target flow conditions. Graft stiffness is influenced by material properties and dimensions and determines graft compliance. This proof-of-concept study evaluated a contact-free method to monitor biomechanical properties without compromising sterility. Forced vibration response analysis was performed on human umbilical vein (HUV) segments mounted in a buffer-filled tubing system. A linear motor and a dynamic signal analyser were used to excite the fluid by white noise (0-200 Hz). Vein responses were read out by laser triangulation and analysed by fast Fourier transformation. Modal analysis was performed by monitoring multiple positions of the vessel surface. As an inverse model of graft stiffening during conditioning, HUV were digested proteolytically, and the course of natural frequencies (NFs) was monitored over 120 min. Human umbilical vein showed up to five modes with NFs in the range of 5-100 Hz. The first natural frequencies of HUV did not alter over time while incubated in buffer (p = 0.555), whereas both collagenase (-35\%, p = 0.0061) and elastase (-45\%, p < 0.001) treatments caused significant decreases of NF within 120 min. Decellularized HUV showed similar results, indicating that changes of the extracellular matrix were responsible for the observed shift in NF. Performing vibration response analysis on vessel grafts is feasible without compromising sterility or integrity of the samples. This technique allows direct measurement of stiffness as an important biomechanical property, obviating the need to monitor surrogate parameters. Copyright (C) 2016 John Wiley \& Sons, Ltd.}, language = {en} } @article{Klemperer, author = {Klemperer, David}, title = {Positionspapier (Einf{\"u}hrung)}, series = {Public Health Forum}, volume = {23}, journal = {Public Health Forum}, number = {1}, publisher = {De Gruyter}, doi = {10.1515/pubhef-2015-0018}, pages = {46}, language = {de} } @article{KlempererBauerFranckeetal., author = {Klemperer, David and Bauer, Ullrich and Francke, Robert and Dierks, Marie-Luise and Robra, Bernt-Peter and Rosenbrock, Rolf and Windeler, J{\"u}rgen}, title = {Positionspapier zur Weiterentwicklung der Gesundheitsversorgungsforschung und zu Themen f{\"u}r k{\"u}nftige Ausschreibungen von Forschungsvorhaben}, series = {Public Health Forum}, volume = {23}, journal = {Public Health Forum}, number = {1}, publisher = {De Gruyter}, doi = {10.1515/pubhef-2015-0019}, pages = {47 -- 50}, language = {de} } @inproceedings{TahedlBorchseniusTaras, author = {Tahedl, Michael and Borchsenius, Fredrik and Taras, Andreas}, title = {Efficient earthquake simulation of stiff and high DOF bridge expansion joint models with Python}, series = {Proceedings of the 10th ECCOMAS Thematic Conference on MULTIBODY DYNAMICS: December 12-15, 2021, Budapest, Hungary}, booktitle = {Proceedings of the 10th ECCOMAS Thematic Conference on MULTIBODY DYNAMICS: December 12-15, 2021, Budapest, Hungary}, publisher = {Budapest University of Technology and Economics}, address = {Budapest, HU}, isbn = {978-963-421-870-8}, doi = {10.3311/ECCOMASMBD2021-196}, pages = {172 -- 183}, abstract = {Various types of seismic protection devices has been developed to protect structures like bridges from collapse during an earthquake event, such as hydraulic or metallic hysteresis dampers and spherical pendulum bearings. The expansion joints however, which are already included in most large-span bridges, are not considered as an earthquake protection device regardless of the significant friction forces they produce. These friction forces can be seen as damping forces between the shaking environment and the oscillating bridge. To investigate the effect of those damping forces during different earthquake loads, a multibody dynamics simulation model of the expansion joints will be created. This model should be accurate enough to represent the generation of the damping forces and effects of the geometric setup of the expansion joints. Because large expansion joints for large-span bridges are of special interest, the number of degrees of freedom (DOF) becomes very high. Because this models include stiff bushings, implicit solvers need to be used to gain a stable simulation. Expansion joints are almost unique constructions for every specific bridge, which requires a automated model generation. Because of its excellent modules for numerical mathematics, the scripting language Python is used. To create an efficient simulation model, several optimization techniques such as Just-In-Time (JIT) compilation and parallelization are implemented and tested.}, language = {en} } @inproceedings{SchneidewindGalka, author = {Schneidewind, Jan and Galka, Stefan}, title = {Interactive reinforcement learning-based factory layout planning}, series = {13th Conference on Learning Factories (CLF 2023), 9-11 May 2023, Reutlingen, Germany}, booktitle = {13th Conference on Learning Factories (CLF 2023), 9-11 May 2023, Reutlingen, Germany}, publisher = {SSRN}, pages = {6}, abstract = {Due to the complexity and the number of factors involved in factory layout planning, computers were identified as an efficient tool to support the process. However, so far no method for computer-aided layout planning has gained wide acceptance in practical application. One reason for this is that in present approaches either the user or the computer designs the layout, neglecting either the qualitative or the quantitative goals. To bridge this gap, this article introduces a concept for human-computer-integration based on evaluative feedback and inverse reinforcement learning. A key element of the concept is the interactive planning process in which user and computer alternately design and improve the layout until a satisfactory layout is found. The user evaluates the layouts according to qualitative criteria, adjusts them intuitively and specifies objectives and restrictions in an explorative way. The computer on the other hand - in form of a reinforcement algorithm - generates possible layouts and incorporates the user's feedback into its policy. This synergy is expected to generate better results than an expert or an algorithm alone could. Furthermore, in the context of learning factories, it encourages critical thinking and allows students to develop a deeper understanding of the factors that contribute to efficient manufacturing processes. Both an architecture for the implementation is proposed and the requirements for the user interface are specified.}, language = {en} } @inproceedings{ThumannJuhartRoecketal., author = {Thumann, Maria and Juhart, J. and R{\"o}ck, R. and Saxer, A. and Galan, Isabel and Mittermayr, F. and Kusterle, Wolfgang}, title = {Entwicklung neuer, dauerhafter und nachhaltiger Spritzbetone}, series = {Kolloquium Forschung \& Entwicklung f{\"u}r Zement und Beton 2018}, booktitle = {Kolloquium Forschung \& Entwicklung f{\"u}r Zement und Beton 2018}, pages = {65 -- 69}, language = {de} } @article{LaumerStichelAmendetal., author = {Laumer, Tobias and Stichel, Thomas and Amend, Philipp and Schmidt, Michael}, title = {Simultaneous laser beam melting of multimaterial polymer parts}, series = {Journal of Laser Applications}, volume = {27}, journal = {Journal of Laser Applications}, number = {S2}, publisher = {Laser Institute of America}, issn = {1938-1387}, doi = {10.2351/1.4906303}, abstract = {By simultaneous laser beam melting (SLBM), parts consisting of different polymer powders can be additively manufactured within one building process. Besides the advantages of conventional LBM, e.g., not needing additional tools and being able to realize parts with almost any geometry, different product requirements can be achieved within a single part. Product requirements may be different chemical resistances or haptic material properties. Therefore, SLBM enlarges the application field for additive manufacturing in general. In the process, two different materials are deposited on the building platform and preheated a few degrees below the melting temperature of the lower melting polymer by infrared emitters. Afterward, a CO2 laser (λ = 10.6 μm) provides the energy for the temperature difference between the preheating temperatures of both materials. Finally, a digital light processing chip is used to achieve simultaneous and flexible energy deposition for melting both preheated polymers. By illuminating the chip with a laser, parts of the beam can be flexibly guided onto the powder bed or into a beam trap. As laser, a single mode thulium laser (λ = 1.94 μm) is used. After melting the layer, a new layer is deposited and the process starts anew. In this paper, polypropylene and polyamide 12 are used as materials. After analyzing the material and melting behavior during the process by a high-resolution thermal imaging system, the parts are qualified regarding their material compatibility at the boundary zone and porosity by cross sections.}, language = {en} } @inproceedings{SakoparnigBaldermannThumannetal., author = {Sakoparnig, Marlene and Baldermann, Andre and Thumann, Maria and Mittermayr, Florian and Kusterle, Wolfgang}, title = {Bestimmung der experimentellen Calcium-Auslaugung an Spritzbetonbohrkernen: Methodenvergleich und Update}, series = {Spritzbeton-Tagung 2018, Alpbach, {\"O}sterreich 11.-12.01.2018}, booktitle = {Spritzbeton-Tagung 2018, Alpbach, {\"O}sterreich 11.-12.01.2018}, abstract = {Im Rahmen des FFG-Forschungsprojektes „Entwicklung neuer dauerhafter und nachhaltiger Spritzbetone (Advanced and sustainable sprayed concrete; ASSpC)" werden Methoden zur Pr{\"u}fung der Calcium-Auslaugung von Spritzbeton eingesetzt bzw. weiterentwickelt. Bestimmt wurde daf{\"u}r das Reduzierte Versinterungspotential nach Regelwerken der {\"O}sterreichischen Bautechnik Vereinigung und das Auslaugverhalten von Spritzbeton bei leichtem S{\"a}ureangriff (Salpeters{\"a}ure und Kohlens{\"a}ure), um dauerhaftigkeitsrelevante Parameter im Bereich der Wechselwirkungen von Spritzbeton mit leicht sauren (Kohlens{\"a}ure- und Nitrathaltigen) Oberfl{\"a}chen-, Grund- und Sickerw{\"a}ssern zu untersuchen und potentielle Sch{\"a}digungsmechanismen zu identifizieren und zu quantifizieren. Die Vor- und Nachteile der verwendeten Pr{\"u}fmethoden zum l{\"o}senden Angriff werden in Bezug auf die Dauerhaftigkeit von Spritzbeton diskutiert.}, language = {de} }