@article{TippkoetterRoikaewUlber2008, author = {Tippk{\"o}tter, Nils and Roikaew, W. and Ulber, R.}, title = {Nitrate removal from whey concentrate with biotechnological regeneration of the waste water}, series = {European dairy magazine : EDM}, journal = {European dairy magazine : EDM}, number = {1}, isbn = {0936-6318}, pages = {30 -- 32}, year = {2008}, language = {en} } @inproceedings{TippkoetterRoikaewUlber2008, author = {Tippk{\"o}tter, Nils and Roikaew, W. and Ulber, R.}, title = {An automated pilot plant for the bioengineering processing of concentrated whey}, series = {European BioPerspectives : in cooperation with BIOTECHNICA 2008 : 7 - 9 October 2008 Hannover, Germany ; book of abstracts ; abstracts, poster programme}, booktitle = {European BioPerspectives : in cooperation with BIOTECHNICA 2008 : 7 - 9 October 2008 Hannover, Germany ; book of abstracts ; abstracts, poster programme}, publisher = {Dechema}, address = {Frankfurt am Main}, pages = {98}, year = {2008}, language = {en} } @incollection{TippkoetterMoehringRothetal.2019, author = {Tippk{\"o}tter, Nils and M{\"o}hring, Sophie and Roth, Jasmine and Wulfhorst, Helene}, title = {Logistics of lignocellulosic feedstocks: preprocessing as a preferable option}, series = {Biorefineries}, booktitle = {Biorefineries}, publisher = {Springer}, address = {Cham}, isbn = {978-3-319-97117-9}, doi = {10.1007/10_2017_58}, pages = {43 -- 68}, year = {2019}, abstract = {In comparison to crude oil, biorefinery raw materials are challenging in concerns of transport and storage. The plant raw materials are more voluminous, so that shredding and compacting usually are necessary before transport. These mechanical processes can have a negative influence on the subsequent biotechnological processing and shelf life of the raw materials. Various approaches and their effects on renewable raw materials are shown. In addition, aspects of decentralized pretreatment steps are discussed. Another important aspect of pretreatment is the varying composition of the raw materials depending on the growth conditions. This problem can be solved with advanced on-site spectrometric analysis of the material.}, language = {en} } @article{TippkoetterDuweWiesenetal.2014, author = {Tippk{\"o}tter, Nils and Duwe, Anna-Maria and Wiesen, Sebastian and Sieker, Tim and Ulber, Roland}, title = {Enzymatic hydrolysis of beech wood lignocellulose at high solid contents and its utilization as substrate for the production of biobutanol and dicarboxylic acids}, series = {Bioresource Technology}, volume = {167}, journal = {Bioresource Technology}, publisher = {Elsevier}, address = {Amsterdam}, doi = {10.1016/j.biortech.2014.06.052}, pages = {447 -- 455}, year = {2014}, abstract = {The development of a cost-effective hydrolysis for crude cellulose is an essential part of biorefinery developments. To establish such high solid hydrolysis, a new solid state reactor with static mixing is used. However, concentrations >10\% (w/w) cause a rate and yield reduction of enzymatic hydrolysis. By optimizing the synergetic activity of cellulolytic enzymes at solid concentrations of 9\%, 17\% and 23\% (w/w) of crude Organosolv cellulose, glucose concentrations of 57, 113 and 152 g L⁻¹ are reached. However, the glucose yield decreases from 0.81 to 0.72gg⁻¹ at 17\% (w/w). Optimal conditions for hydrolysis scale-up under minimal enzyme addition are identified. As result, at 23\% (w/w) crude cellulose the glucose yield increases from 0.29 to 0.49gg⁻¹. As proof of its applicability, biobutanol, succinic and itaconic acid are produced with the crude hydrolysate. The potential of the substrate is proven e.g. by a high butanol yield of 0.33gg⁻¹.}, language = {en} } @article{TippkoetterDeterdingUlber2008, author = {Tippk{\"o}tter, Nils and Deterding, A. and Ulber, Roland}, title = {Determination of acetic acid in fermentation broth by gas-diffusion technique}, series = {Engineering in Life Sciences}, volume = {8}, journal = {Engineering in Life Sciences}, number = {1, Special Issue: Technical Systems for the Use in Life Sciences}, doi = {10.1002/elsc.200820227}, pages = {62 -- 67}, year = {2008}, abstract = {Due to the interfering effects of acetic acid in many fermentation processes, a gas-diffusion technique was developed for the online determination of acetic acid. The measurements were accomplished with a flow diffusion analysis (FDA) unit from the TRACE Analytics GmbH, Braunschweig, Germany. The diffusion analysis is based on the UV-absorbance of acetic acid at 205 nm. The measurement was achieved by the separation of an acceptor and a carrier stream (acidified fermentation broth) using a gas permeable polytetrafluoroethylene (PTFE) membrane, whereby broth constituents that would otherwise disturb the UV-measurement of acetic acid, are held back efficiently. Merely, the fermentation by-products, e.g. formic acid, is capable of diffusing through the membrane. While formic acid can disturb the measurement, carbon dioxide does not absorb at 205 nm. The method operates with time-dependent sample enrichment. During the analysis, a small volume of the acceptor stream is stopped for a defined time interval in the acceptor chamber. During this period, the gaseous acetic acid diffuses through the membrane and is enriched in the acceptor chamber. Subsequently after the enrichment, the acceptor stream flows through a UV-detector. The intensity of the signal is proportional to the acetic acid concentration. Online measurements in bioreactors via a sterile filtration probe have been accomplished. A linear calibration in the range of 0.5-5.0 g/L acetic acid with a relative standard deviation of <5 \% was obtained. A sampling rate of 8 samples per hour was possible. The system was applied for the determination of acetic acid in E. coli fermentation broth. The instrument is easy to clean, very user-friendly and does not require any toxic or expensive reagents.}, language = {en} } @article{TippkoetterAlKaidyWollnyetal.2013, author = {Tippk{\"o}tter, Nils and Al-Kaidy, Huschyar and Wollny, Steffen and Ulber, Roland}, title = {Functionalized magnetizable particles for downstream processing in single-use systems}, series = {Chemie Ingenieur Technik}, volume = {85}, journal = {Chemie Ingenieur Technik}, number = {1-2: Special Issue: Single-Use Technology}, publisher = {Wiley}, address = {Weinheim}, doi = {10.1002/cite.201200130}, pages = {76 -- 86}, year = {2013}, abstract = {Biotechnological downstream processing is usually an elaborate procedure, requiring a multitude of unit operations to isolate the target component. Besides the disadvantageous space-time yield, the risks of cross-contaminations and product loss grow fast with the complexity of the isolation procedure. A significant reduction of unit operations can be achieved by application of magnetic particles, especially if these are functionalized with affinity ligands. As magnetic susceptible materials are highly uncommon in biotechnological processes, target binding and selective separation of such particles from fermentation or reactions broths can be done in a single step. Since the magnetizable particles can be produced from iron salts and low priced polymers, a single-use implementation of these systems is highly conceivable. In this article, the principles of magnetizable particles, their synthesis and functionalization are explained. Furthermore, applications in the area of reaction engineering, microfluidics and downstream processing are discussed focusing on established single-use technologies and development potential.}, language = {en} } @article{TillmannFoerster2000, author = {Tillmann, K. and F{\"o}rster, Arnold}, title = {Critical dimensions for the formation of interfacial misfit dislocations of In0.6Ga0.4As islands on GaAs(001)}, series = {Thin Solid Films. 368 (2000), H. 1}, journal = {Thin Solid Films. 368 (2000), H. 1}, isbn = {0040-6090}, pages = {93 -- 104}, year = {2000}, language = {en} } @article{ThustSchoeningFrohnhoffetal.1996, author = {Thust, Marion and Sch{\"o}ning, Michael Josef and Frohnhoff, S. and Arens-Fischer, R. and Kordos, P. and L{\"u}th, H.}, title = {Porous silicon as a substrate material for potentiometric biosensors}, series = {Measurement Science and Technology}, volume = {7}, journal = {Measurement Science and Technology}, number = {1}, doi = {10.1088/0957-0233/7/1/003}, pages = {26 -- 29}, year = {1996}, language = {en} } @article{ThustSchoeningSchrothetal.1999, author = {Thust, M. and Sch{\"o}ning, Michael Josef and Schroth, P. and Malkoc, {\"U}. and Dicker, C. I. and Steffen, A. and Kordos, P. and L{\"u}th, H.}, title = {Enzyme immobilisation on planar and porous silicon substrates for biosensor applications}, series = {Journal of Molecular Catalysis B: Enzymatic. 7 (1999), H. 1-4}, journal = {Journal of Molecular Catalysis B: Enzymatic. 7 (1999), H. 1-4}, isbn = {1381-1177}, pages = {77 -- 83}, year = {1999}, language = {en} } @article{ThustSchrothToepleretal.1998, author = {Thust, M. and Schroth, P. and T{\"o}pler, A. and Sch{\"o}ning, Michael Josef and M{\"u}ller-Veggian, Mattea and Kordos, P. and L{\"u}th, H.}, title = {Improving the detection limit of a capacitive sensor by means of a diffusion barrier}, series = {Eurosensors XII : proceedings of the 12th European Conference on Solid-State Transducers and the 9th UK Conference on Sensors and their Applications, Southampton, UK, 13 - 16 September 1998 / ed. by N. M. White ; Vol. 1}, journal = {Eurosensors XII : proceedings of the 12th European Conference on Solid-State Transducers and the 9th UK Conference on Sensors and their Applications, Southampton, UK, 13 - 16 September 1998 / ed. by N. M. White ; Vol. 1}, publisher = {Inst. of Physics Publ.}, address = {Bristol [u.a.]}, isbn = {0-7503-0595-9}, pages = {507 -- 510}, year = {1998}, language = {en} } @article{ThustPoghossianSchoeningetal.1999, author = {Thust, M. and Poghossian, Arshak and Sch{\"o}ning, Michael Josef and Naser, S. and M{\"u}ller-Veggian, Mattea and Kordos, P. and L{\"u}th, H.}, title = {Crosssensitivity of a capacitive penicillin sensor combined with a diffusion barrier}, series = {Proceedings : The Hague, The Netherlands, September 12 - 15, 1999 / [ed. by M. Bartek]. Vol 1.}, journal = {Proceedings : The Hague, The Netherlands, September 12 - 15, 1999 / [ed. by M. Bartek]. Vol 1.}, address = {The Hague, The Netherlands}, isbn = {90-76699-02-X}, pages = {573 -- 576}, year = {1999}, language = {en} } @article{ThustPoghossianSchoeningetal.1999, author = {Thust, M. and Poghossian, Arshak and Sch{\"o}ning, Michael Josef and Naser, S. and M{\"u}ller-Veggian, Mattea and Kordos, P. and L{\"u}th, H.}, title = {Cross-sensitivity of a capacitive penicillin sensor combined with a diffusion barrier}, series = {Proceedings : The Hague, The Netherlands, September 12 - 15, 1999 / [ed. by M. Bartek]. - Vol 1.}, journal = {Proceedings : The Hague, The Netherlands, September 12 - 15, 1999 / [ed. by M. Bartek]. - Vol 1.}, address = {The Hague, The Netherlands}, isbn = {90-76699-02-X}, pages = {573 -- 576}, year = {1999}, language = {en} } @inproceedings{ThurnGebhardt2017, author = {Thurn, Laura and Gebhardt, Andreas}, title = {Arousing Enthusiasm for STEM: Teaching 3D Printing Technology}, series = {Conference Proceedings: New Perspectives in Science Education}, booktitle = {Conference Proceedings: New Perspectives in Science Education}, publisher = {liberiauniversitaria.it}, address = {Padua}, isbn = {978-88-6292-847-2}, pages = {87 -- 92}, year = {2017}, language = {en} } @inproceedings{ThurnGebhardt2018, author = {Thurn, Laura and Gebhardt, Andreas}, title = {Strategy of Education on Materials for Students}, series = {Conference Proceedings: „New Perspectives in Science Education"}, booktitle = {Conference Proceedings: „New Perspectives in Science Education"}, address = {Florence, Italy}, isbn = {978-88-6292-976-9}, pages = {156 -- 161}, year = {2018}, language = {en} } @inproceedings{ThurnBalcGebhardtetal.2017, author = {Thurn, Laura and Balc, Nicolae and Gebhardt, Andreas and Kessler, Julia}, title = {Education packed in technology to promote innovations: Teaching Additive Manufacturing based on a rolling Lab}, series = {Modern Technologies in Manufacturing (MTeM 2017 - AMaTUC)}, booktitle = {Modern Technologies in Manufacturing (MTeM 2017 - AMaTUC)}, issn = {2261-236X}, doi = {10.1051/matecconf/201713702013}, pages = {6 Seiten}, year = {2017}, language = {en} } @article{ThomessenThomaBraun2023, author = {Thomessen, Karolin and Thoma, Andreas and Braun, Carsten}, title = {Bio-inspired altitude changing extension to the 3DVFH* local obstacle avoidance algorithm}, series = {CEAS Aeronautical Journal}, journal = {CEAS Aeronautical Journal}, publisher = {Springer}, address = {Wien}, issn = {1869-5590 (Online)}, doi = {10.1007/s13272-023-00691-w}, pages = {11 Seiten}, year = {2023}, abstract = {Obstacle avoidance is critical for unmanned aerial vehicles (UAVs) operating autonomously. Obstacle avoidance algorithms either rely on global environment data or local sensor data. Local path planners react to unforeseen objects and plan purely on local sensor information. Similarly, animals need to find feasible paths based on local information about their surroundings. Therefore, their behavior is a valuable source of inspiration for path planning. Bumblebees tend to fly vertically over far-away obstacles and horizontally around close ones, implying two zones for different flight strategies depending on the distance to obstacles. This work enhances the local path planner 3DVFH* with this bio-inspired strategy. The algorithm alters the goal-driven function of the 3DVFH* to climb-preferring if obstacles are far away. Prior experiments with bumblebees led to two definitions of flight zone limits depending on the distance to obstacles, leading to two algorithm variants. Both variants reduce the probability of not reaching the goal of a 3DVFH* implementation in Matlab/Simulink. The best variant, 3DVFH*b-b, reduces this probability from 70.7 to 18.6\% in city-like worlds using a strong vertical evasion strategy. Energy consumption is higher, and flight paths are longer compared to the algorithm version with pronounced horizontal evasion tendency. A parameter study analyzes the effect of different weighting factors in the cost function. The best parameter combination shows a failure probability of 6.9\% in city-like worlds and reduces energy consumption by 28\%. Our findings demonstrate the potential of bio-inspired approaches for improving the performance of local path planning algorithms for UAV.}, language = {en} } @article{ThomaThomessenGardietal.2023, author = {Thoma, Andreas and Thomessen, Karolin and Gardi, Alessandro and Fisher, A. and Braun, Carsten}, title = {Prioritising paths: An improved cost function for local path planning for UAV in medical applications}, series = {The Aeronautical Journal}, journal = {The Aeronautical Journal}, number = {First View}, publisher = {Cambridge University Press}, address = {Cambridge}, issn = {0001-9240 (Print)}, doi = {10.1017/aer.2023.68}, pages = {1 -- 18}, year = {2023}, abstract = {Even the shortest flight through unknown, cluttered environments requires reliable local path planning algorithms to avoid unforeseen obstacles. The algorithm must evaluate alternative flight paths and identify the best path if an obstacle blocks its way. Commonly, weighted sums are used here. This work shows that weighted Chebyshev distances and factorial achievement scalarising functions are suitable alternatives to weighted sums if combined with the 3DVFH* local path planning algorithm. Both methods considerably reduce the failure probability of simulated flights in various environments. The standard 3DVFH* uses a weighted sum and has a failure probability of 50\% in the test environments. A factorial achievement scalarising function, which minimises the worst combination of two out of four objective functions, reaches a failure probability of 26\%; A weighted Chebyshev distance, which optimises the worst objective, has a failure probability of 30\%. These results show promise for further enhancements and to support broader applicability.}, language = {en} } @inproceedings{ThomaStiemerBraunetal.2023, author = {Thoma, Andreas and Stiemer, Luc and Braun, Carsten and Fisher, Alex and Gardi, Alessandro G.}, title = {Potential of hybrid neural network local path planner for small UAV in urban environments}, series = {AIAA SCITECH 2023 Forum}, booktitle = {AIAA SCITECH 2023 Forum}, publisher = {AIAA}, doi = {10.2514/6.2023-2359}, pages = {13 Seiten}, year = {2023}, abstract = {This work proposes a hybrid algorithm combining an Artificial Neural Network (ANN) with a conventional local path planner to navigate UAVs efficiently in various unknown urban environments. The proposed method of a Hybrid Artificial Neural Network Avoidance System is called HANNAS. The ANN analyses a video stream and classifies the current environment. This information about the current Environment is used to set several control parameters of a conventional local path planner, the 3DVFH*. The local path planner then plans the path toward a specific goal point based on distance data from a depth camera. We trained and tested a state-of-the-art image segmentation algorithm, PP-LiteSeg. The proposed HANNAS method reaches a failure probability of 17\%, which is less than half the failure probability of the baseline and around half the failure probability of an improved, bio-inspired version of the 3DVFH*. The proposed HANNAS method does not show any disadvantages regarding flight time or flight distance.}, language = {en} } @article{ThomaRavi2019, author = {Thoma, Andreas and Ravi, Sridhar}, title = {Significance of parallel computing on the performance of Digital Image Correlation algorithms in MATLAB}, pages = {1 -- 17}, year = {2019}, abstract = {Digital Image Correlation (DIC) is a powerful tool used to evaluate displacements and deformations in a non-intrusive manner. By comparing two images, one of the undeformed reference state of a specimen and another of the deformed target state, the relative displacement between those two states is determined. DIC is well known and often used for post-processing analysis of in-plane displacements and deformation of specimen. Increasing the analysis speed to enable real-time DIC analysis will be beneficial and extend the field of use of this technique. Here we tested several combinations of the most common DIC methods in combination with different parallelization approaches in MATLAB and evaluated their performance to determine whether real-time analysis is possible with these methods. To reflect improvements in computing technology different hardware settings were also analysed. We found that implementation problems can reduce the efficiency of a theoretically superior algorithm such that it becomes practically slower than a suboptimal algorithm. The Newton-Raphson algorithm in combination with a modified Particle Swarm algorithm in parallel image computation was found to be most effective. This is contrary to theory, suggesting that the inverse-compositional Gauss-Newton algorithm is superior. As expected, the Brute Force Search algorithm is the least effective method. We also found that the correct choice of parallelization tasks is crucial to achieve improvements in computing speed. A poorly chosen parallelisation approach with high parallel overhead leads to inferior performance. Finally, irrespective of the computing mode the correct choice of combinations of integerpixel and sub-pixel search algorithms is decisive for an efficient analysis. Using currently available hardware realtime analysis at high framerates remains an aspiration.}, language = {en} } @inproceedings{ThomaFisherBraun2020, author = {Thoma, Andreas and Fisher, Alex and Braun, Carsten}, title = {Improving the px4 avoid algorithm by bio-inspired flight strategies}, series = {DLRK2020 - „Luft- und Raumfahrt - Verantwortung in allen Dimensionen"}, booktitle = {DLRK2020 - „Luft- und Raumfahrt - Verantwortung in allen Dimensionen"}, pages = {10 Seiten}, year = {2020}, language = {en} }