@inproceedings{ButenwegGellertReindl2008, author = {Butenweg, Christoph and Gellert, Christoph and Reindl, Lukas}, title = {Capacity design of masonry buildings under cyclic loading}, series = {Seismic Risk : Earthquakes in North-Western Europe ; international colloquium ; Li{\`e}ge on 11 and 12 September 2008 / Belgian Seismic Group (BeSeiG). Ed.: T. Camlebeeck ...}, booktitle = {Seismic Risk : Earthquakes in North-Western Europe ; international colloquium ; Li{\`e}ge on 11 and 12 September 2008 / Belgian Seismic Group (BeSeiG). Ed.: T. Camlebeeck ...}, publisher = {Editions de l'Universit{\´e} de Li{\`e}ge}, address = {Li{\`e}ge}, organization = {Belgian Seismic Group}, isbn = {978-2-87456-063-7}, pages = {201 -- 208}, year = {2008}, language = {en} } @inproceedings{ButenwegGellert2008, author = {Butenweg, Christoph and Gellert, Christoph}, title = {Displacement based design of masonry structures}, series = {Proceedings of the 14th International Brick and Block Masonry Conference : (Incorporating the 8th Australasian Masonry Conference) : Sydney, Australia, 13.-20. February 2008 / ed. Mark Masia ...}, booktitle = {Proceedings of the 14th International Brick and Block Masonry Conference : (Incorporating the 8th Australasian Masonry Conference) : Sydney, Australia, 13.-20. February 2008 / ed. Mark Masia ...}, publisher = {University of Newcastle}, address = {Callaghan}, organization = {International Brick and Block Masonry Conference <14, 2008, Sydney>}, isbn = {978-19-2070-1-92-5}, pages = {1 -- 10}, year = {2008}, language = {en} } @article{ThomaGardiFisheretal.2024, author = {Thoma, Andreas and Gardi, Alessandro and Fisher, Alex and Braun, Carsten}, title = {Improving local path planning for UAV flight in challenging environments by refining cost function weights}, series = {CEAS Aeronautical Journal}, journal = {CEAS Aeronautical Journal}, publisher = {Springer}, address = {Wien}, issn = {1869-5590 (eISSN)}, doi = {10.1007/s13272-024-00741-x}, pages = {12 Seiten}, year = {2024}, abstract = {Unmanned Aerial Vehicles (UAV) constantly gain in versatility. However, more reliable path planning algorithms are required until full autonomous UAV operation is possible. This work investigates the algorithm 3DVFH* and analyses its dependency on its cost function weights in 2400 environments. The analysis shows that the 3DVFH* can find a suitable path in every environment. However, a particular type of environment requires a specific choice of cost function weights. For minimal failure, probability interdependencies between the weights of the cost function have to be considered. This dependency reduces the number of control parameters and simplifies the usage of the 3DVFH*. Weights for costs associated with vertical evasion (pitch cost) and vicinity to obstacles (obstacle cost) have the highest influence on the failure probability of the local path planner. Environments with mainly very tall buildings (like large American city centres) require a preference for horizontal avoidance manoeuvres (achieved with high pitch cost weights). In contrast, environments with medium-to-low buildings (like European city centres) benefit from vertical avoidance manoeuvres (achieved with low pitch cost weights). The cost of the vicinity to obstacles also plays an essential role and must be chosen adequately for the environment. Choosing these two weights ideal is sufficient to reduce the failure probability below 10\%.}, language = {en} } @inproceedings{KuhlmannButenwegLopezetal.2004, author = {Kuhlmann, Wolfram and Butenweg, Christoph and Lopez, Marijen and Fernandez, Sebastian}, title = {Seismic vulnerability assessment of the historic Aachen Cathedral}, series = {Conference proceedings / 13th World Conference on Earthquake Engineering [Vancouver, British Columbia, Canada, August 1 - 6, 2004] / [hosted by CAEE/ACGP, Canadian Association for Earthquake Engineering]}, booktitle = {Conference proceedings / 13th World Conference on Earthquake Engineering [Vancouver, British Columbia, Canada, August 1 - 6, 2004] / [hosted by CAEE/ACGP, Canadian Association for Earthquake Engineering]}, publisher = {CAEE}, address = {Vancouver}, organization = {World Conference on Earthquake Engineering <13, 2004, Vancouver>}, pages = {1 -- 14}, year = {2004}, language = {en} } @inproceedings{MeskourisButenwegMistleretal.2004, author = {Meskouris, Konstantin and Butenweg, Christoph and Mistler, Michael and Kuhlmann, Wolfram}, title = {Seismic behaviour of historic masonry buildings}, series = {7th National Congress on Mechanics : Chania, Crete, June 24 - 26, 2004 ; proceedings / ed. A. Kounadis ....}, booktitle = {7th National Congress on Mechanics : Chania, Crete, June 24 - 26, 2004 ; proceedings / ed. A. Kounadis ....}, publisher = {Hellenic Society for Theoretical and Applied Mechanics}, address = {Chania}, organization = {National Congress on Mechanics <7, 2004, Chania, Crete>}, pages = {47 -- 49}, year = {2004}, language = {en} } @article{EdipGarevskiButenwegetal.2013, author = {Edip, Kemal and Garevski, Mihail and Butenweg, Christoph and Sesov, Vlatko and Cvetanovska, Julijana and Gjorgiev, Igor}, title = {Numerical simulation of geotechnical problems by coupled finite and infinite elements}, series = {Journal of civil engineering and architecture}, volume = {7}, journal = {Journal of civil engineering and architecture}, number = {1}, publisher = {David Publishing}, address = {Libertyville}, issn = {1934-7359 (E-Journal)}, pages = {68 -- 77}, year = {2013}, language = {en} } @article{GoemmelButenwegBolenderetal.2007, author = {G{\"o}mmel, Andreas and Butenweg, Christoph and Bolender, Katrin and Grunendahl, Arno}, title = {A muscle controlled finite-element model of laryngeal abduction and adduction}, series = {Computer methods in biomechanics and biomedical engineering}, volume = {Volume 10}, journal = {Computer methods in biomechanics and biomedical engineering}, number = {Issue 5}, issn = {1476-8259 (E-Journal); 1025-5842 (Print)}, pages = {377 -- 388}, year = {2007}, language = {en} } @article{RochefortVerverGrunendahletal.2005, author = {Rochefort, E. de and Verver, M. and Grunendahl, A. and Mooi, H. and Butenweg, Christoph}, title = {Detailed modelling of the lumbar spine for investigations of low back pain}, series = {SAE transactions : papers presented at Society and Section meetings / Society of Automotive Engineers}, volume = {Volume 114}, journal = {SAE transactions : papers presented at Society and Section meetings / Society of Automotive Engineers}, number = {Part 7}, organization = {Society of Automotive Engineers}, issn = {0096-736X}, pages = {788 -- 796}, year = {2005}, language = {en} } @article{HoltschoppenButenwegMeskouris2009, author = {Holtschoppen, Britta and Butenweg, Christoph and Meskouris, Konstantin}, title = {Seismic design of non-structural components in industrial facilities}, series = {International journal of engineering under uncertainty}, volume = {Volume 1}, journal = {International journal of engineering under uncertainty}, issn = {0975-4806}, pages = {1 -- 13}, year = {2009}, language = {en} } @inproceedings{EggertWeber2023, author = {Eggert, Mathias and Weber, Jannik}, title = {What drives the purchase decision in Instagram stores?}, series = {ECIS 2023 Research Papers}, booktitle = {ECIS 2023 Research Papers}, pages = {1 -- 17}, year = {2023}, abstract = {The popularity of social media and particularly Instagram grows steadily. People use the different platforms to share pictures as well as videos and to communicate with friends. The potential of social media platforms is also being used for marketing purposes and for selling products. While for Facebook and other online social media platforms the purchase decision factors are investigated several times, Instagram stores remain mainly unattended so far. The present research work closes this gap and sheds light into decisive factors for purchasing products offered in Instagram stores. A theoretical research model, which contains selected constructs that are assumed to have a significant influence on Instagram user´s purchase intention, is developed. The hypotheses are evaluated by applying structural equation modelling on survey data containing 127 relevant participants. The results of the study reveal that 'trust', 'personal recommendation', and 'usability' significantly influences user's buying intention in Instagram stores.}, language = {en} } @incollection{ButenwegThierauf1999, author = {Butenweg, Christoph and Thierauf, G.}, title = {Automatic design of reinforced concrete structures with parallel computing}, series = {Innovative computational methods for structural mechanics}, booktitle = {Innovative computational methods for structural mechanics}, editor = {Papadrakakis, M. and Topping, B.H.V.}, publisher = {Saxe-Coburg Publication}, address = {Edinburgh}, isbn = {1-874672-05-9}, doi = {10.4203/csets.1.14}, pages = {305 -- 318}, year = {1999}, abstract = {A concept for the analysis and optimal design of reinforced concrete structures is described. It is based on a nonlinear optimization algorithm and a finite element program for linear and nonlinear analysis of structures. With the aim of minimal cost design a two stage optimization using efficient gradient algorithm is developed. The optimization problems on global (structural) and local (crosssectional) level are formulated. A parallelization concept for solving the two stage optimization problem in minimal time is presented. Examples are included to illustrate the practical use and the effectively of the parallelization in the area of engineering design.}, language = {en} } @incollection{MeskourisButenwegKalkeretal.2007, author = {Meskouris, Konstantin and Butenweg, Christoph and Kalker, Ines and Mistler, Michael}, title = {Numerical simulation of historic masonry buildings}, series = {Antike Erdbeben im alpinen und zirkumalpinen Raum : Befunde und Probleme in arch{\"a}ologischer, historischer und seismologischer Sicht ; Beitr{\"a}ge des Interdisziplin{\"a}ren Workshops Schloss Hohenkammer, 14./15. Mai 2004 = Earthquakes in antiquity in the alpine and circum-alpine region / Gerhard H. Waldherr ; Anselm Smolka (Hrsg.) (Geographica Historica ; 24)}, booktitle = {Antike Erdbeben im alpinen und zirkumalpinen Raum : Befunde und Probleme in arch{\"a}ologischer, historischer und seismologischer Sicht ; Beitr{\"a}ge des Interdisziplin{\"a}ren Workshops Schloss Hohenkammer, 14./15. Mai 2004 = Earthquakes in antiquity in the alpine and circum-alpine region / Gerhard H. Waldherr ; Anselm Smolka (Hrsg.) (Geographica Historica ; 24)}, publisher = {Franz Steiner Verlag}, address = {Stuttgart}, isbn = {978-3-515-09030-8 ; 3-515-09030-4}, pages = {171 -- 189}, year = {2007}, language = {en} } @inproceedings{MarinkovicButenweg2020, author = {Marinkovic, Marko and Butenweg, Christoph}, title = {Seismic behaviour of RC frames with uncoupled masonry infills having two storeys or two bays}, series = {Brick and Block Masonry - From Historical to Sustainable Masonry. Proceedings of the 17th International Brick/Block Masonry Conference}, booktitle = {Brick and Block Masonry - From Historical to Sustainable Masonry. Proceedings of the 17th International Brick/Block Masonry Conference}, publisher = {CRC Press}, address = {London}, doi = {10.1201/9781003098508-72}, pages = {1 -- 7}, year = {2020}, abstract = {Reinforced concrete (RC) structures with masonry infills are widely used for several types of buildings all over the world. However, it is well known that traditional masonry infills constructed with rigid contact to the surrounding RC frame performed rather poor in past earthquakes. Masonry infills showed severe in-plane damages and failed in many cases under out-of-plane seismic loading. As the undesired interactions between frames and infills changes the load transfer on building level, complete collapses of buildings were observed. A possible solution is uncoupling of masonry infills to the frame to reduce the infill contribution activated by the frame deformation under horizontal loading. The paper presents numerical simulations on RC frames equipped with the innovative decoupling system INODIS. The system was developed within the European project INSYSME and allows an effective uncoupling of frame and infill. The simulations are carried out with a micro-modelling approach, which is able to predict the complex nonlinear behaviour resulting from the different materials and their interaction. Each brick is modelled individually and connected taking into account nonlinearity of a brick mortar interface. The calibration of the model is based on small specimen tests and experimental results for one bay one storey frame are used for the validation. The validated model is further used for parametric studies on two storey and two bay infilled frames. The response and change of the structural stiffness are analysed and compared to the traditionally infilled frame. The results confirm the effectiveness of the INODIS system with less damage and relatively low contribution of the infill at high drift levels. In contrast to the uncoupled system configurations, traditionally infilled frames experienced brittle failure at rather low drift levels.}, language = {en} } @inproceedings{MichelRosinButenwegetal.2020, author = {Michel, Philipp and Rosin, Julia and Butenweg, Christoph and Klinkel, Sven}, title = {Soil-dependent earthquake spectra in the analysis of liquid-storage-tanks on compliant soil}, series = {Seismic design of industrial facilities 2020}, booktitle = {Seismic design of industrial facilities 2020}, publisher = {Apprimus Verlag}, address = {Aachen}, isbn = {978-3-86359-729-0}, pages = {245 -- 254}, year = {2020}, abstract = {A further development of the Added-Mass-Method allows the combined representation of the effects of both soil-structure-interaction and fluid-structure interaction on a liquid-filled-tank in one model. This results in a practical method for describing the dynamic fluid pressure on the tank shell during joint movement. The fluid pressure is calculated on the basis of the tank's eigenform and the earthquake acceleration and represented by additional masses on the shell. The bearing on compliant ground is represented by replacement springs, which are calculated dependent on the local soil composition. The influence of the shear modulus of the compliant soil is clearly visible in the pressure curves and the stress distribution in the shell. The acceleration spectra are also dependent on soil stiffness. According to Eurocode-8 the acceleration spectra are determined for fixed soil-classes, instead of calculating the accelerations for each site in direct dependence on the soil composition. This leads to unrealistic sudden changes in the system's response. Therefore, earthquake spectra are calculated for different soil models in direct dependence of the shear modulus. Thus, both the acceleration spectra and the replacement springs match the soil composition. This enables a reasonable and consistent calculation of the system response for the actual conditions at each site.}, language = {en} } @inproceedings{MarkinkovicButenwegPaveseetal.2020, author = {Markinkovic, Marko and Butenweg, Christoph and Pavese, A. and Lanese, I. and Hoffmeister, B. and Pinkawa, M. and Vulcu, C. and Bursi, O. and Nardin, C. and Paolacci, F. and Quinci, G. and Fragiadakis, M. and Weber, F. and Huber, P. and Renault, P. and G{\"u}ndel, M. and Dyke, S. and Ciucci, M. and Marino, A.}, title = {Investigation of the seismic behaviour of structural and nonstructural components in industrial facilities by means of shaking table tests}, series = {Seismic design of industrial facilities 2020}, booktitle = {Seismic design of industrial facilities 2020}, publisher = {Apprimus Verlag}, address = {Aachen}, isbn = {978-3-86359-729-0}, pages = {159 -- 172}, year = {2020}, language = {en} } @inproceedings{CacciatoreButenweg2020, author = {Cacciatore, Pamela and Butenweg, Christoph}, title = {Seismic safety of cylindrical granular material steel silos under seismic loading}, series = {Seismic design of industrial facilities 2020}, booktitle = {Seismic design of industrial facilities 2020}, publisher = {Apprimus Verlag}, address = {Aachen}, isbn = {978-3-86359-729-0}, pages = {231 -- 244}, year = {2020}, language = {en} } @inproceedings{GrundmannBauerBodenetal.2019, author = {Grundmann, Jan Thimo and Bauer, Waldemar and Boden, Ralf Christian and Ceriotti, Matteo and Cordero, Federico and Dachwald, Bernd and Dumont, Etienne and Grimm, Christian D. and Hercik, D. and Herique, A. and Ho, Tra-Mi and Jahnke, Rico and Kofman, Wlodek and Lange, Caroline and Lichtenheldt, Roy and McInnes, Colin R. and Mikschl, Tobias and Montenegro, Sergio and Moore, Iain and Pelivan, Ivanka and Peloni, Alessandro and Plettenmeier, Dirk and Quantius, Dominik and Reershemius, Siebo and Renger, Thomas and Riemann, Johannes and Rogez, Yves and Ruffer, Michael and Sasaki, Kaname and Schmitz, Nicole and Seboldt, Wolfgang and Seefeldt, Patric and Spietz, Peter and Spr{\"o}witz, Tom and Sznajder, Maciej and Toth, Norbert and Viavattene, Giulia and Wejmo, Elisabet and Wolff, Friederike and Ziach, Christian}, title = {Responsive exploration and asteroid characterization through integrated solar sail and lander development using small spacecraft technologies}, series = {IAA Planetary Defense Conference}, booktitle = {IAA Planetary Defense Conference}, year = {2019}, abstract = {In parallel to the evolution of the Planetary Defense Conference, the exploration of small solar system bodies has advanced from fast fly-bys on the sidelines of missions to the planets to the implementation of dedicated sample-return and in-situ analysis missions. Spacecraft of all sizes have landed, touch-and-go sampled, been gently beached, or impacted at hypervelocity on asteroid and comet surfaces. More have flown by close enough to image their surfaces in detail or sample their immediate environment, often as part of an extended or re-purposed mission. And finally, full-scale planetary defense experiment missions are in the making. Highly efficient low-thrust propulsion is increasingly applied beyond commercial use also in mainstream and flagship science missions, in combination with gravity assist propulsion. Another development in the same years is the growth of small spacecraft solutions, not in size but in numbers and individual capabilities. The on-going NASA OSIRIS-REx and JAXA HAYABUSA2 missions exemplify the trend as well as the upcoming NEA SCOUT mission or the landers MINERVA-II and MASCOT recently deployed on Ryugu. We outline likely as well as possible and efficient routes of continuation of all these developments towards a propellant-less and highly efficient class of spacecraft for small solar system body exploration: small spacecraft solar sails designed for carefree handling and equipped with carried landers and application modules, for all asteroid user communities -planetary science, planetary defence, and in-situ resource utilization. This projection builds on the experience gained in the development of deployable membrane structures leading up to the successful ground deployment test of a (20 m)² solar sail at DLR Cologne and in the 20 years since. It draws on the background of extensive trajectory optimization studies, the qualified technology of the DLR GOSSAMER-1 deployment demonstrator, and the MASCOT asteroid lander. These enable 'now-term' as well as near-term hardware solutions, and thus responsive fast-paced development. Mission types directly applicable to planetary defense include: single and Multiple NEA Rendezvous ((M)NR) for mitigation precursor, target monitoring and deflection follow-up tasks; sail-propelled head-on retrograde kinetic impactors (RKI) for mitigation; and deployable membrane based methods to modify the asteroid's properties or interact with it. The DLR-ESTEC GOSSAMER Roadmap initiated studies of missions uniquely feasible with solar sails such as Displaced L1 (DL1) space weather advance warning and monitoring and Solar Polar Orbiter (SPO) delivery which demonstrate the capability of near-term solar sails to achieve NEA rendezvous in any kind of orbit, from Earth-coorbital to extremely inclined and even retrograde orbits. For those mission types using separable payloads, such as SPO, (M)NR and RKI, design concepts can be derived from the separable Boom Sail Deployment Units characteristic of DLR GOSSAMER solar sail technology, nanolanders like MASCOT, or microlanders like the JAXA-DLR Jupiter Trojan Asteroid Lander for the OKEANOS mission which can shuttle from the sail to the asteroids visited and enable multiple NEA sample-return missions. These are an ideal match for solar sails in micro-spacecraft format whose launch configurations are compatible with ESPA and ASAP secondary payload platforms.}, language = {en} } @incollection{AkimbekovDigelSherelkhanetal.2022, author = {Akimbekov, Nuraly S. and Digel, Ilya and Sherelkhan, Dinara K. and Razzaque, Mohammed S.}, title = {Vitamin D and Phosphate Interactions in Health and Disease}, series = {Phosphate Metabolism}, booktitle = {Phosphate Metabolism}, publisher = {Springer}, address = {Cham}, isbn = {978-3-030-91621-3}, doi = {10.1007/978-3-030-91623-7_5}, pages = {37 -- 46}, year = {2022}, abstract = {Vitamin D plays an essential role in calcium and inorganic phosphate (Pi) homeostasis, maintaining their optimal levels to assure adequate bone mineralization. Vitamin D, as calcitriol (1,25(OH)2D), not only increases intestinal calcium and phosphate absorption but also facilitates their renal reabsorption, leading to elevated serum calcium and phosphate levels. The interaction of 1,25(OH)2D with its receptor (VDR) increases the efficiency of intestinal absorption of calcium to 30-40\% and phosphate to nearly 80\%. Serum phosphate levels can also influence 1,25 (OH)2D and fibroblast growth factor 23 (FGF23) levels, i.e., higher phosphate concentrations suppress vitamin D activation and stimulate parathyroid hormone (PTH) release, while a high FGF23 serum level leads to reduced vitamin D synthesis. In the vitamin D-deficient state, the intestinal calcium absorption decreases and the secretion of PTH increases, which in turn causes the stimulation of 1,25(OH)2D production, resulting in excessive urinary phosphate loss. Maintenance of phosphate homeostasis is essential as hyperphosphatemia is a risk factor of cardiovascular calcification, chronic kidney diseases (CKD), and premature aging, while hypophosphatemia is usually associated with rickets and osteomalacia. This chapter elaborates on the possible interactions between vitamin D and phosphate in health and disease.}, language = {en} } @inproceedings{MoehrenBergmannJanseretal.2023, author = {M{\"o}hren, Felix and Bergmann, Ole and Janser, Frank and Braun, Carsten}, title = {On the determination of harmonic propeller loads}, series = {AIAA SCITECH 2023 Forum}, booktitle = {AIAA SCITECH 2023 Forum}, publisher = {AIAA}, doi = {10.2514/6.2023-2404}, pages = {12 Seiten}, year = {2023}, abstract = {Dynamic loads significantly impact the structural design of propeller blades due to fatigue and static strength. Since propellers are elastic structures, deformations and aerodynamic loads are coupled. In the past, propeller manufacturers established procedures to determine unsteady aerodynamic loads and the structural response with analytical steady-state calculations. According to the approach, aeroelastic coupling primarily consists of torsional deformations. They neglect bending deformations, deformation velocities, and inertia terms. This paper validates the assumptions above for a General Aviation propeller and a lift propeller for urban air mobility or large cargo drones. Fully coupled reduced-order simulations determine the dynamic loads in the time domain. A quasi-steady blade element momentum approach transfers loads to one-dimensional finite beam elements. The simulation results are in relatively good agreement with the analytical method for the General Aviation propeller but show increasing errors for the slender lift propeller. The analytical approach is modified to consider the induced velocities. Still, inertia and velocity proportional terms play a significant role for the lift propeller due to increased elasticity. The assumption that only torsional deformations significantly impact the dynamic loads of propellers is not valid. Adequate determination of dynamic loads of such designs requires coupled aeroelastic simulations or advanced analytical procedures.}, language = {en} } @inproceedings{Dachwald2005, author = {Dachwald, Bernd}, title = {Global optimization of low-thrust space missions using evolutionary neurocontrol}, series = {Proceedings of the international workshop on global optimization}, booktitle = {Proceedings of the international workshop on global optimization}, pages = {85 -- 90}, year = {2005}, abstract = {Low-thrust space propulsion systems enable flexible high-energy deep space missions, but the design and optimization of the interplanetary transfer trajectory is usually difficult. It involves much experience and expert knowledge because the convergence behavior of traditional local trajectory optimization methods depends strongly on an adequate initial guess. Within this extended abstract, evolutionary neurocontrol, a method that fuses artificial neural networks and evolutionary algorithms, is proposed as a smart global method for low-thrust trajectory optimization. It does not require an initial guess. The implementation of evolutionary neurocontrol is detailed and its performance is shown for an exemplary mission.}, language = {en} }