@inproceedings{MildeGeislingerLindtetal., author = {Milde, Benjamin and Geislinger, Robert and Lindt, Irina and Baumann, Timo}, title = {Open Source Automatic Lecture Subtitling}, series = {Proceedings of Elektronische Sprachsignalverarbeitung (ESSV): Tagungsband der 32. Konferenz, Berlin, 3.-5. M{\"a}rz 2021}, booktitle = {Proceedings of Elektronische Sprachsignalverarbeitung (ESSV): Tagungsband der 32. Konferenz, Berlin, 3.-5. M{\"a}rz 2021}, publisher = {F{\"o}rderverein Elektronische Sprachsignalverabeitung e.V.}, address = {Berlin, Germany}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:18-228-7-2523}, pages = {128 -- 135}, abstract = {We present a fully automatic solution for German video subtitling, with a focus on lecture videos. We rely entirely on open source models and scripts for German ASR, automatic punctuation reconstruction and subtitle segmentation. All training scripts, 1000h of German speech training data, pre-trained models and the final subtitling program are publicly available. It can readily be integrated into lecture video platforms such as Lecture2Go. The automatically generated subtitles can also serve as a basis to make the video material more accessible (e.g. via search, keyword clouds, and the like) or for further manual revision, potentially helping in significantly speeding up manual work. A particular challenge that we observe in lectures are technical terms that are frequent in a particular lecture, but infrequent in a typical language model and that might be out of vocabulary for a general purpose ASR. We approach this challenge by extracting texts from accompanying lecture slides to adapt the language model of our TDNN-HMM based ASR system. We demonstrate the usability of the full system and its generated subtitles and evaluate on a dataset of manually transcribed lectures with an average of 26.3\% WER.}, language = {en} } @inproceedings{HusseinMeyerSickendiekBaumann, author = {Hussein, Hussein and Meyer-Sickendiek, Burkhard and Baumann, Timo}, title = {How to identify elliptical poems within a digital corpus of auditory poetry}, series = {Elektronische Sprachsignalverarbeitung 2019 (ESSV), Tagungsband der 30. Konferenz, Dresden, 3.-8. M{\"a}rz 2019}, booktitle = {Elektronische Sprachsignalverarbeitung 2019 (ESSV), Tagungsband der 30. Konferenz, Dresden, 3.-8. M{\"a}rz 2019}, editor = {Birkholz, Peter and Stone, Simon}, publisher = {TUDpress}, address = {Dresden, Germany}, isbn = {978-3-959081-57-3}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:18-228-7-2579}, pages = {247 -- 254}, abstract = {Ellipses denote the omission of one or more grammatically necessary phrases. In this paper, we will demonstrate how to identify such ellipses as a rhythmical pattern in modern and postmodern free verse poetry by using data from lyrikline which contain the corresponding audio recording of each poem as spoken by the original author. We present a feature engineering approach based on literary analysis as well as a neural networks based approach for the identification of ellipses within the lines of a poem. A contrast class to the ellipsis is defined from poems consisting of complete and correct sentences. The feature-based approach used features derived from a parser such as verb, comma, and sentence ending punctuation. The classifier of neural networks is trained on the line level to integrate the textual information, the spoken recitation, and the pause information between lines, and to integrate information across the lines within the poem. A statistic analysis of poet's gender showed that 65\% of all elliptical poems were written by female poets. The best results, calculated by the weighted F-measure, for the classification of ellipsis with the contrast class is 0.94 with the neural networks based approach. The best results for classification of elliptical lines is 0.62 with the feature-based approach.}, language = {en} } @inproceedings{BaumannMeyerSickendiekHussein, author = {Baumann, Timo and Meyer-Sickendiek, Burkhard and Hussein, Hussein}, title = {How to Identify Speech When Translating Unpunctuated Poetry}, series = {Proceedings of Elektronische Sprachsignalverarbeitung: Tagungsband der 31. Konferenz, Magdeburg, 4.-6. M{\"a}rz 2020}, booktitle = {Proceedings of Elektronische Sprachsignalverarbeitung: Tagungsband der 31. Konferenz, Magdeburg, 4.-6. M{\"a}rz 2020}, publisher = {F{\"o}rderverein Elektronische Sprachsignalverabeitung e.V.}, address = {Magdeburg, Germany}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:18-228-7-2587}, pages = {165 -- 172}, abstract = {A large proportion of (post)-modern poetry contains no or hardly any punctuation. In our contribution, we will investigate how well punctuation information can be recovered for postmodern poetry based on the information contained in the text and speech of free verse poems. We use the world's largest corpus of spoken (post-)modern poetry from our partner lyrikline which contains the corresponding audio recording of each poem as spoken by the original author and features translations for many of the poems. We identify lines that contain a phrase break in the middle of the poetic line, which may already be helpful for philological analysis on one hand, and identify the position of the break in the line on the other hand. We select those poetic lines that contain one or more punctuation characters that typically indicate a phrase break in poetry (.,;:!?/) somewhere in the middle (rather than only at the end of the line) as our target class. We train a neural network (bidirectional recurrent neural network (RNN) based on gated recurrent units (GRU) with attention) that combines audio and textual features to identify the punctuation with the goal of applying it to reconstruct them within a corpus of unpunctuated poems. Our results clearly indicate that speech is helpful for recovering the constituency structure of post-modern poetry that is partially obfuscated by missing punctuation.}, language = {en} } @inproceedings{BaumannSaboo, author = {Baumann, Timo and Saboo, Ashutosh}, title = {Evaluating Heuristics for Audio-Visual Translation}, series = {Proceedings of the Conference of Computational Humanities Research, (CHR2021): November 17-19, 2021, Amsterdam, The Netherlands}, booktitle = {Proceedings of the Conference of Computational Humanities Research, (CHR2021): November 17-19, 2021, Amsterdam, The Netherlands}, editor = {Ehrmann, Maud}, publisher = {CEUR Workshops}, address = {Amsterdam, the Netherlands}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:18-228-7-2592}, pages = {171 -- 180}, abstract = {Dubbing, i.e., the lip-synchronous translation and revoicing of audio-visual media into a target language from a different source language, is essential for the full-fledged reception of foreign audio-visual media, be it movies, instructional videos or short social media clips. In this paper, we objectify influences on the 'dubbability' of translations, i.e., how well a translation would be synchronously revoiceable to the lips on screen. We explore the value of traditional heuristics used in evaluating the qualitative aspects, in particular matching bilabial consonants and the jaw opening while producing vowels, and control for quantity, i.e., that translations are similar to the source in length. We perform an ablation study using an adversarial neural classifier which is trained to differentiate "true" dubbing translations from machine translations. While we are able to confirm the value of matching lip closure in dubbing, we find that the opening angle of the jaw as determined by the realized vowel may be less relevant than frequently considered in audio-visual translation.}, language = {en} } @article{WeissGarloff, author = {Weiss, Matthias and Garloff, Alfred}, title = {Skill-biased technological change and endogenous benefits: The dynamics of unemployment and wage inequality}, series = {Applied Economics}, volume = {43}, journal = {Applied Economics}, number = {7}, publisher = {Taylor \& Francis}, issn = {1466-4283}, doi = {10.1080/00036840802599933}, url = {http://nbn-resolving.de/urn:nbn:de:0168-ssoar-242195}, pages = {811 -- 821}, abstract = {In this paper, we study the effect of skill-biased technological change on unemployment and wage inequality in the presence of a link between social benefits and average income. In this case, an increase in the productivity of skilled workers and hence their wage leads to an increase in average income and hence in benefits. The increased fallback income, in turn, makes unskilled workers ask for higher wages. As higher wages are not justified by respective productivity increases, unemployment rises. More generally, we show that skill-biased technological change leads to increasing unemployment of the unskilled and to a moderately increasing wage inequality when benefits are endogenous. The model provides a theoretical explanation for diverging dynamics in wage inequality and unemployment under different social benefits regimes: Analyzing the social legislation in 14 countries, we find that benefits are linked to the evolution of average income in Continental Europe but not in the U.S. and the UK. Given this institutional difference, our model predicts that skill-biased technological change leads to rising unemployment in Continental Europe and rising wage inequality in the U.S. and the UK....}, language = {en} } @inproceedings{Baumann, author = {Baumann, Timo}, title = {Coordinating Speech Delivery to Gesture Progress for Deictic Expressions with Incremental Speech Synthesis}, series = {Proceedings of the Timing in Human-Robot Interaction Workshop held in conjunction with the 9th ACM/IEEE International Conference on Human-Robot Interaction (HRI 2014), Bielefeld, 3. March 2014}, booktitle = {Proceedings of the Timing in Human-Robot Interaction Workshop held in conjunction with the 9th ACM/IEEE International Conference on Human-Robot Interaction (HRI 2014), Bielefeld, 3. March 2014}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:18-228-7-1991}, abstract = {This paper presents ongoing work in incremental speech synthesis that enables a system to adapt speech delivery to unforeseen changes in the timing of motor events (e. g. a robot actuator working faster or slower than anticipated) in order to improve the coordination of speech and gestures for deictic expressions.}, subject = {Sprachverarbeitung}, language = {en} } @phdthesis{Frikel, author = {Frikel, J{\"u}rgen}, title = {Reconstructions in limited angle x-ray tomography: Characterization of classical reconstructions and adapted curvelet sparse regularization}, publisher = {Technische Universit{\"a}t M{\"u}nchen}, address = {M{\"u}nchen}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:91-diss-20130328-1115037-0-3}, abstract = {This thesis is devoted to the problem of tomographic reconstruction at limited angular range. In the first part, we prove a characterization of filtered backprojection reconstructions from limited angle data. Moreover, we develop a strategy for artifact reduction and stabilization. In the second part, we introduce a new edge-preserving reconstruction algorithm for limited angle tomography and analyze this algorithm mathematically. Some numerical experiments are also presented.}, language = {en} } @misc{MeyerSickendiekBaumannHussein, author = {Meyer-Sickendiek, Burkhard and Baumann, Timo and Hussein, Hussein}, title = {Requirements on the Punctuation Reconstruction for the Translation of Post-modern Poetry}, series = {DHd 2020 ; Spielr{\"a}ume ; Digital Humanities zwischen Modellierung und Interpretation ; Konferenzabstracts ; Universit{\"a}t Paderborn 02. bis 06. M{\"a}rz 2020}, journal = {DHd 2020 ; Spielr{\"a}ume ; Digital Humanities zwischen Modellierung und Interpretation ; Konferenzabstracts ; Universit{\"a}t Paderborn 02. bis 06. M{\"a}rz 2020}, publisher = {Universit{\"a}t Paderborn}, address = {Paderborn}, isbn = {978-3-945437-07-0}, doi = {10.5281/zenodo.4621722}, language = {en} } @misc{Baumann, author = {Baumann, Timo}, title = {Ubiquity of Computing and SLIVAR}, series = {Spoken Language Interaction with Virtual Agents and Robots (SLIVAR): Towards Effective and Ethical Interaction}, volume = {10}, journal = {Spoken Language Interaction with Virtual Agents and Robots (SLIVAR): Towards Effective and Ethical Interaction}, editor = {Devillers, Laurence and Kawahara, Tatsuya and Moore, Roger K. and Scheutz, Matthias}, publisher = {Schloss Dagstuhl - Leibniz-Zentrum f{\"u}r Informatik}, address = {Dagstuhl, Germany}, doi = {10.4230/DagRep.10.1.1}, url = {http://nbn-resolving.de/urn:nbn:de:0030-drops-124009}, pages = {16}, language = {en} } @misc{MeyerSickendiekHusseinBaumann, author = {Meyer-Sickendiek, Burkhard and Hussein, Hussein and Baumann, Timo}, title = {From Fluency To Disfluency: Ranking Prosodic Features Of Poetry By Using Neural Networks}, series = {Proceedings of the International Conference on Digital Humanities (DH 2019), Utrecht, the Netherlands 9-12 July, 2019}, journal = {Proceedings of the International Conference on Digital Humanities (DH 2019), Utrecht, the Netherlands 9-12 July, 2019}, doi = {10.34894/EGZNMI}, language = {en} } @inproceedings{LaumerSchmidtStichel, author = {Laumer, Tobias and Schmidt, Michael and Stichel, Thomas}, title = {Influence of temperature gradients on the part properties for the simultaneous laser beam melting of polymers}, series = {Proceedings of Laser in Manfacturing Conference 2015, June 22 - June 25, 2015 Munich, Germany}, booktitle = {Proceedings of Laser in Manfacturing Conference 2015, June 22 - June 25, 2015 Munich, Germany}, organization = {German Scientific Laser Society (WLT e.V.)}, abstract = {By Laser Beam Melting of polymers (LBM), parts with almost any geometry can be built directly out of CAD files without the need for additional tools. Thus, prototypes or parts in small series production can be generated within short times. Up to now, no multi-material parts have been built by LBM, which is a major limitation of the technology. To realize multi-material parts, new mechanisms for depositing different polymer powders as well as a new irradiation strategy are needed, by which polymers with different melting temperatures can be warmed to their specific preheating temperatures and be molten simultaneously. This is achieved by simultaneous laser beam melting (SLBM). In the process, two different materials are deposited next to each other and preheated a few degrees below their melting temperatures by infrared emitters and laser radiation (λ = 10.60 µm), before in the last step the two preheated powders are molten simultaneously by an additional laser (λ = 1.94 µm). So far, multi-material tensile bars have been realized and analyzed regarding their boundary zone between both materials. The experiments showed that the temperature gradients in the boundary zone and along the building direction seem to be of great importance for the process stability and the resulting part properties. Therefore, a detailed analysis of the occurring temperature gradients during the process is needed to identify adequate process adjustments regarding the temperature controlling. To analyze the temperature gradients, thermocouples positioned inside the powder bed are used. By varying the temperature of the building platform, the influence of different temperature gradients on the resulting part properties is shown.}, language = {en} } @article{StichelLaumerLinnenweberetal., author = {Stichel, Thomas and Laumer, Tobias and Linnenweber, Tim and Amend, Philipp and Roth, Stephan}, title = {Mass Flow Characterization of Selective Deposition of Polymer Powders with Vibrating Nozzles for Laser Beam Melting of Multi-material Components}, series = {Physics Procedia}, volume = {83}, journal = {Physics Procedia}, publisher = {Elsevier}, address = {Amsterdam [u.a.]}, issn = {1875-3892}, doi = {10.1016/j.phpro.2016.08.099}, pages = {947 -- 953}, abstract = {The generation of multi-material components by laser beam melting (LBM) is a challenge which requires the invention of new coating devices for preparation of arbitrary powder patterns. One solution is the usage of vibration-controlled nozzles for selective deposition of polymer powders. Powder flow can be initiated by vibration enabling a start-stop function without using any mechanical shutter. In this report, the delivery of polymer powder by vibrating nozzles is investigated with respect to their application in LBM machines. Therefore, a steel nozzle attached to a piezo actor and a weighing cell is used in order to measure the stability and time-dependence of the powder mass flow upon vibration excitation with the usage of different kind of powder formulations. The results show that precompression of the powder inside the nozzle by vibration excitation is essential to realize a reliable start-stop function with reproducible discharge cyles and to prevent a initial flush of powder flow. Moreover, the use of different powder materials showed that mass flow is even possible with powders which are not optimized regarding flowability, but is readily enhanced with a factor of 2 to 3 by admixing Aerosil® fumed silica.}, language = {en} } @inproceedings{LaumerKoopmannSticheletal., author = {Laumer, Tobias and Koopmann, Jonas and Stichel, Thomas and Amend, Philipp}, title = {Generation of multi-material parts with alternating material layers by Simultaneous Laser Beam Meltingof polymers}, series = {International Conference on Additive Technologies, 15 - 17 Oct 2014, Wien}, booktitle = {International Conference on Additive Technologies, 15 - 17 Oct 2014, Wien}, abstract = {By using Additive Manufacturing technologies, like Laser Beam Melting (LBM) of polymers, parts can be realized within single days and necessary modifications can be quickly adapted. With increasing complexity, products are often made out of different polymer materials and the need for multi-material parts is an increasing industry requirement, which cannot be fulfilled by the single material parts realizable by LBM. Therefore, Simultaneous Laser Beam Melting (SLBM) as a new Additive Manufacturing technology offers the possibility to build parts consisting of different polymer materials. The realizable parts combine different material properties, like differing stiffness or chemical resistances, within a single part. Up to now, different materials are deposited next to each other on the building platform, thus the boundary surface between the different polymers is orientated perpendicular to the building direction. For this paper, the polymer powders are alternated in building direction. Thus, the boundary surface is orientated horizontally and is larger, both influencing the boundary surface and resulting part properties, which are analyzed by a high-resolution thermal imaging system and by cross sections.}, language = {en} } @inproceedings{StichelAmendLaumeretal., author = {Stichel, Thomas and Amend, Philipp and Laumer, Tobias and Roth, Stephan}, title = {Electrostatic Multi-Material Powder Deposition for Simultaneous Laser Beam Melting}, series = {International Conference on Information, Communication and Automation Technologies (ICAT), 2014, Wien}, booktitle = {International Conference on Information, Communication and Automation Technologies (ICAT), 2014, Wien}, abstract = {In this paper, the use of electrostatic polymer powder transfer methods for the preparation of multi-material layers is discussed with respect to the application in Simultaneous Laser Beam Melting (SLBM). Therefore, the basic principles of the single process steps as well as the challenges in combination with SLBM are considered verifying the critical process steps. On that base, process concepts are developed which might enable the fabrication of high quality multi-material parts in the future. Moreover, since the polymer powders typically used with Laser Beam Melting differ strongly from common toners for e. g. electrophotographic printing, an experimental setup was built to study the powder transfer with an electrically chargeable transfer plate using polyamide 12 powder. The results of this study show that transfer of powders usable for Laser Beam Melting can be achieved, but depends on the electric field strength which is a function of the gap between transfer and substrate plate and the intermediate electric potential.}, language = {en} } @article{StichelAmendLaumeretal., author = {Stichel, Thomas and Amend, Philipp and Laumer, Tobias and Roth, Stephan}, title = {Polymer Powder Deposition using Vibrating Capillary Nozzles for Additive Manufacturing}, series = {Information, Communication and Automation Technologies (ICAT), 2014, Wien}, journal = {Information, Communication and Automation Technologies (ICAT), 2014, Wien}, abstract = {Abstract — In this report, the dry delivery of polyamide 12 (PA 12) powder for the preparation of powder layers in laser beam melting (LBM) is investigated. Therefore, an experimental setup was built which consists of a glass nozzle assembled on a piezo-electric actuator. By applying a sinusoidal voltage signal to the actuator, the nozzle is set into vibration mode which enhances the powder delivery through the nozzle. By using this effect, powder mass flow is controlled and a valve-like start and stop function is realized. In order to identify suitable process parameters, a broad range of vibration modes were investigated using two nozzles made from glass with different orifice diameters. Therefore, the vibration frequency and the voltage signal of the actuator were varied and the resulting mass flow was detected by a balance. It was found that both the frequency and the voltage signal affect the mass flow and its stability but with different impact. Moreover, powder lines were deposited with different velocities in order to characterize the setup regarding applicability for highly selective powder deposition for LBM.}, language = {en} } @article{StichelLaumerBaumuelleretal., author = {Stichel, Thomas and Laumer, Tobias and Baum{\"u}ller, Tobias and Amend, Philipp and Roth, Stephan}, title = {Powder Layer Preparation Using Vibration-controlled Capillary Steel Nozzles for Additive Manufacturing}, series = {Physics Procedia}, volume = {56}, journal = {Physics Procedia}, publisher = {Elsevier}, issn = {1875-3892}, doi = {10.1016/j.phpro.2014.08.158}, pages = {157 -- 166}, abstract = {In this report, the dry delivery of polyamide 12 powders by vibrating capillary steel nozzles is investigated and discussed regarding its potential for powder layer preparation in Laser Beam Melting. Therefore, a setup including a steel nozzle assembled on a piezoelectric actuator is presented, which enables the precise control over very small powder quantities by vibration excitation. An analysis reveals that the mass flow through the nozzle can be adjusted by the vibration modes in a certain range depending on the nozzle's specifications, whereas the vibration modes themselves show a complicated behaviour. Using a positioning system in combination with the vibrating nozzle, single-layer patterns consisting of polyamide 12 are produced and characterized regarding surface homogeneity and selectivity using a laser stripe sensor.}, language = {en} } @article{LaumerStichelRiedlbaueretal., author = {Laumer, Tobias and Stichel, Thomas and Riedlbauer, Daniel and Amend, Philipp and Mergheim, Julia and Schmidt, Michael}, title = {Realization of multi-material polymer parts by simultaneous laser beam melting}, series = {Journal of Laser Micro / Nanoengineering}, volume = {10}, journal = {Journal of Laser Micro / Nanoengineering}, number = {2}, publisher = {Japan Laser Processing Society}, abstract = {In this paper, first results regarding the realization of multi-material parts by Simultaneous Laser Beam Melting (SLBM) of polymers are presented. This new approach allows the layerwise generation of parts consisting of different polymer materials within one building process. Besides the typical advantages of additive manufacturing technologies, such parts can fulfill different product requirements concomitant and therefore could enlarge the overall field of application. The powder materials used for this paper are polyethylene (PE) and a polyamide based thermoplastic elastomer (TPE). After depositing the powder materials next to each other, infrared-emitters heat the lower melting polymer and a CO2 laser provides the preheating temperature of the higher melting polymer. In the last step, a thulium fibre laser melts the two preheated powders simultaneously. The realized specimens are characterized by cross sections and their tensile strengths are determined. Additionally, the new approach of the simultaneous energy irradiation is investigated using a Finite Element Analysis in order to gain a more profound process understanding. In that sense, the influence of the size of the exposure area on the reachable maximum temperatures inside that area was analyzed by the simulation and compared to experimental studies.}, language = {en} } @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{StichelAmendLaumeretal., author = {Stichel, Thomas and Amend, Philipp and Laumer, Tobias and Roth, Stephan}, title = {Multi-material deposition of polymer powders with vibrating nozzles inside laser beam melting machines}, series = {6th International Conference on Additive Technologies - iCAT 2016 : proceedings : N{\"u}rnberg, Germany, 29.-30. November 2016}, booktitle = {6th International Conference on Additive Technologies - iCAT 2016 : proceedings : N{\"u}rnberg, Germany, 29.-30. November 2016}, publisher = {Interesansa - zavod}, address = {Ljubljana}, abstract = {The generation of multi-material components using Laser beam melting (LBM) is a challenge which requires the invention of new coating devices for the preparation of arbitrary powder patterns. One solution is the usage of vibration-controlled nozzles for selective deposition of polymer powders. Powder flow can be initiated by vibration even when using powders with low flowability. In this report, the selective deposition of polymer powder by vibrating nozzles is investigated with respect to their application in LBM machines. Therefore, a steel nozzle attached to a piezo actor is applied, whereas the nozzle itself features internal channels which allow the precise control of the powder temperature using heat transfer oil. The setup is used to study the influence of temperature on the powder mass flow. The results show that, next to the vibration mode, the temperature strongly influences the powder mass flow which is done by affecting the moisture and thus the particle-particle adhesion forces. This shows that a precise control of the powder temperature inside the nozzle is required in order to achieve a constant mass flow and thus a successful application of vibrating nozzles inside LBM machines.}, language = {en} } @article{StichelGeisslerJanderetal., author = {Stichel, Thomas and Geißler, Bastian and Jander, Julius and Laumer, Tobias and Frick, Thomas and Roth, Stephan}, title = {Electrophotographic multi-material powder deposition for additive manufacturing}, series = {Journal of Laser Applications}, volume = {30}, journal = {Journal of Laser Applications}, number = {3}, publisher = {AIP Publishing}, doi = {10.2351/1.5040619}, abstract = {In this paper, the use of electrophotographic polymer powder transfer for the preparation of multi-material layers is discussed with respect to the application in powder bed-based additive manufacturing technologies as selective laser sintering (SLS). Therefore, the challenges of this task are considered verifying the critical process steps in order to develop a concept for an electrophotograhic laser sintering machine. On that basis, an experimental setup with a two-chamber design is realized which enables the investigation of the electrophotographic powder transfer at typical process conditions of SLS. Using this setup, transfer tests of polypropylene powder patterns were performed and qualitatively analyzed by photographic imaging. The results confirm the high potential of the application of electrophotography for multi-material powder deposition and show how a residual electrophotographic powder deposition can be achieved in general, which is independent from the already produced part height, in order to build up three-dimensional multi-material components.}, language = {en} } @inproceedings{LaumerStichelAmendetal., author = {Laumer, Tobias and Stichel, Thomas and Amend, Philipp and Roth, Stephan and Schmidt, Michael}, title = {Analysis of Temperature Gradients during Simultaneous Laser Beam Melting of Polymers}, series = {Physics Procedia}, volume = {56}, booktitle = {Physics Procedia}, publisher = {Elsevier}, doi = {10.1016/j.phpro.2014.08.159}, pages = {167 -- 175}, abstract = {By simultaneous laser beam melting (SLBM), different polymer powders can be processed to multi-material parts, which offers the potential to enlarge the field of application for conventional LBM. In a SLBM process, a powder bed consisting of different polymers and therefore with different melting and crystallization temperatures is deposited. Besides the use of infrared emitters for preheating the lower melting polymer, a CO2 laser distributes the necessary preheating temperature of the higher melting polymer. In the last step, a thulium fibre laser distributes the energy necessary for melting the two preheated powders simultaneously. In order to analyze the temperature gradients of the process on the powder surface and in deeper layers, a high-resolution thermal imaging system and thermocouples are used.}, language = {en} } @inproceedings{StichelLaumerAmendetal., author = {Stichel, Thomas and Laumer, Tobias and Amend, Philipp and Wittmann, Peter}, title = {Selective deposition of polymer powder by vibrating nozzles for laser beam melting}, series = {Proceedings of Laser in Manfacturing Conference 2015, June 22, 2015 - June 25, 2015, Munich, Germany}, booktitle = {Proceedings of Laser in Manfacturing Conference 2015, June 22, 2015 - June 25, 2015, Munich, Germany}, abstract = {In this report, the delivery of polyamide 12 (PA 12) powder and powder layer preparation by vibrating steel nozzles is investigated and discussed with respect to its application for laser beam melting. Therefore, a setup was realized which includes a steel nozzle attached to a piezo actor as well as a positioning system. In order t o investigate the mass flow characteristics in dependency on the applied vibration state, a weighing cell is used enabling time-resolved mass flow measurements. Moreover, single-layer patterns consisting of colored and uncolored polyamide 12 were created and characterized regarding surface homogeneity and selectivity before as well as after the melting of the powder layers by a hot plate.}, language = {en} } @article{StichelLaumerSchmidt, author = {Stichel, Thomas and Laumer, Tobias and Schmidt, Michael}, title = {Simulation des (quasi-)simultanen Laserstrahlschmelzens zur Herstellung von Multi-Material-Bauteilen aus Polymeren}, series = {Rapid.Tech + FabCon 3.D - International Trade Show + Conference for Additive Manufacturing}, journal = {Rapid.Tech + FabCon 3.D - International Trade Show + Conference for Additive Manufacturing}, publisher = {Hanser}, doi = {10.3139/9783446458123.020}, pages = {312 -- 329}, language = {en} } @misc{Schulz, author = {Schulz, Carsten}, title = {Maintenance Prediction using Realtime Digital Twins}, series = {Dassault Syst{\`e}mes User Conference 2018, Hanau, Germany, 4-6 December}, journal = {Dassault Syst{\`e}mes User Conference 2018, Hanau, Germany, 4-6 December}, language = {en} } @misc{TsaiBaumannPecuneetal., author = {Tsai, Vivian and Baumann, Timo and Pecune, Florian and Cassell, Justine}, title = {Faster Responses are Better Responses: Introducing Incrementality into Sociable Virtual Personal Assistants}, language = {en} } @misc{ThielGehlenFoestl, author = {Thiel, Charlotte and Gehlen, Christoph and F{\"o}stl, Florian}, title = {Service life prediction of concrete under freeze-thaw deicing salt attack with intermittent dry periodst}, series = {The Sixth International Symposium on Life-Cycle Civil Engineering : IALCCE 2018,28 -31.10.2018, Ghent}, journal = {The Sixth International Symposium on Life-Cycle Civil Engineering : IALCCE 2018,28 -31.10.2018, Ghent}, language = {en} } @misc{SchliermannHeydenreichBungteretal., author = {Schliermann, Rainer and Heydenreich, Patrick and Bungter, Tanja and Anneken, Volker}, title = {Analysis of motivational factors and physical activity and sport of people with visual impairments in vocational promotion centers [Abstract]}, series = {Proceedings 14th European Congress of Sport Psychology : Sport Psychology - Theories and Applications for Performance, Health and Humanity ; 14-19 July 2015, Bern, Switzerland}, journal = {Proceedings 14th European Congress of Sport Psychology : Sport Psychology - Theories and Applications for Performance, Health and Humanity ; 14-19 July 2015, Bern, Switzerland}, editor = {Schmid, Oliver and Seiler, Roland}, publisher = {University of Bern, Institut of Sport Science}, address = {Bern}, isbn = {978-3-033-05129-4}, pages = {230}, language = {en} } @misc{Frikel, author = {Frikel, J{\"u}rgen}, title = {Adapted curvelet sparse regularization in limited angle tomography}, series = {Summer School: New Trends and Directions in Harmonic Analysis, Fractional Operator Theory, and Image Analysis, Inzell, Germany, September 17 - 21, 2012}, journal = {Summer School: New Trends and Directions in Harmonic Analysis, Fractional Operator Theory, and Image Analysis, Inzell, Germany, September 17 - 21, 2012}, language = {en} } @misc{PaetzelSchlesingerPricopetal., author = {Paetzel, Maike and Schlesinger, Philipp and Pricop, Mircea and Comaneci, Radu and Baumann, Timo and Menzel, Wolfgang}, title = {Inkrementelle und zustandsbasierte Verarbeitung in einem hybriden Sprachdialogsystem}, language = {en} } @misc{ChowWhiteBruceetal., author = {Chow, Rosan and White, Hazel and Bruce, Fraser and Press, Michael}, title = {Rip+Mix: A Design Method Emerging from Case Transfer}, editor = {Lalande, Philippe}, publisher = {University of Dundee}, address = {Montreal}, language = {en} } @misc{PfingstenBorgettoTomlinetal., author = {Pfingsten, Andrea and Borgetto, Bernhard and Tomlin, George S. and Max, Susanne and Trickes, Claudia}, title = {The Research Pyramid. Establishing the value of evidence from multiple research approaches in a systematic review}, series = {World Physical Therapy Congress der World Confederation for Physical Therapy (WCPT), Amsterdam, 2011}, journal = {World Physical Therapy Congress der World Confederation for Physical Therapy (WCPT), Amsterdam, 2011}, abstract = {Goal: The Research Pyramid is a model that values and integrates external evidence from multiple research approaches: experimental and observational as well as quantitative and qualitative. It provides a basis to collect and synthesize research findings for answering questions that emerge in therapy practice and for subsequent decision making, based on research evidence.}, language = {en} } @misc{Haug, author = {Haug, Sonja}, title = {Migration Trends from Central and Eastern Europe to Germany}, series = {Conference of the International Union for the Scientific Study in Population (IUSSP), 18.-23.7.2005, Tours}, journal = {Conference of the International Union for the Scientific Study in Population (IUSSP), 18.-23.7.2005, Tours}, language = {en} } @misc{SchuetzOvrutcki, author = {Sch{\"u}tz, Sandra and Ovrutcki, Claudia}, title = {Ethnographic study in an inclusive classroom}, series = {Inclusive and Supportive Education Congress Equity and Inclusion in Education (ISEC2015), 8th, Juli 2015, Lisbon/Portugal}, journal = {Inclusive and Supportive Education Congress Equity and Inclusion in Education (ISEC2015), 8th, Juli 2015, Lisbon/Portugal}, language = {en} } @inproceedings{SelgradLierKoeferletal., author = {Selgrad, Kai and Lier, Alexander and K{\"o}ferl, Franz and Stamminger, Marc and Lohmann, Daniel}, title = {Lightweight, Generative Variant Exploration for High-performance Graphics Applications}, series = {GPCE'15 : Proceedings of the 2015 ACM SIGPLAN International Conference on Generative Programming: Concepts and Experiences ; October 26-27, 2015, Pittsburgh, PA, USA}, booktitle = {GPCE'15 : Proceedings of the 2015 ACM SIGPLAN International Conference on Generative Programming: Concepts and Experiences ; October 26-27, 2015, Pittsburgh, PA, USA}, editor = {K{\"a}stner, Christian and Gokhāl{\´e}, Anir{\"u}ddhā}, publisher = {ACM}, address = {New York, USA}, isbn = {978-1-4503-3687-1}, pages = {141 -- 150}, abstract = {Rendering performance is an everlasting goal of computer graphics and significant driver for advances in both, hardware architecture and algorithms. Thereby, it has become possible to apply advanced computer graphics technology even in low-cost embedded appliances, such as car instruments. Yet, to come up with an efficient implementation, developers have to put enormous efforts into hardware/problem-specific tailoring, fine-tuning, and domain exploration, which requires profound expert knowledge. If a good solution has been found, there is a high probability that it does not work as well with other architectures or even the next hardware generation. Generative DSL-based approaches could mitigate these efforts and provide for an efficient exploration of algorithmic variants and hardware-specific tuning ideas. However, in vertically organized industries, such as automotive, suppliers are reluctant to introduce these techniques as they fear loss of control, high introduction costs, and additional constraints imposed by the OEM with respect to software and tool-chain certification. Moreover, suppliers do not want to share their generic solutions with the OEM, but only concrete instances. To this end, we propose a light-weight and incremental approach for meta programming of graphics applications. Our approach relies on an existing formulation of C-like languages that is amenable to meta programming, which we extend to become a lightweight language to combine algorithmic features. Our method provides a concise notation for meta programs and generates easily sharable output in the appropriate C-style target language.}, language = {en} } @inproceedings{LierMartinekStammingeretal., author = {Lier, Alexander and Martinek, Magdalena and Stamminger, Marc and Selgrad, Kai}, title = {A High-Resolution Compression Scheme for Ray Tracing Subdivision Surfaces with Displacement}, series = {Proceedings of the ACM on Computer Graphics and Interactive Techniques}, volume = {1}, booktitle = {Proceedings of the ACM on Computer Graphics and Interactive Techniques}, number = {2}, publisher = {The Association for Computers in Mathematics and Science Teaching}, doi = {10.1145/3233308}, pages = {1 -- 17}, abstract = {Subdivision surfaces, especially with displacement, are one of the key modeling primitives used in high-quality rendering environments, such as, e.g., movie production. While their use easily maps to rasterization-based frameworks, they pose a significant challenge for ray tracing environments. This is due to the fact that incoherent access patterns require storing or caching fully tessellated and displaced meshes for efficient intersection computations. In this paper we use a two-tier hierarchy built on a scene's patches. It relies on compressed and quantized bounding volumes on the second tier to reduce the size of the BVH itself. Based on this acceleration structure, we propose a quantized, compact approximation for leaf nodes while being faithful to the underlying patch-geometry. We build on recent advances and present a system that shows competitive performance regarding run-time speed, which is close to full-resolution pre-tessellation methods as well as to previous compression approaches. Ultimately, we provide strong compression of up to a factor of 5: 1 compared to state-of-the-art methods while maintaining high geometrical fidelity surpassing similarly compact approximations and getting close to uncompressed geometry.}, language = {en} } @inproceedings{BaumannPaetzelSchlesingeretal., author = {Baumann, Timo and Paetzel, Maike and Schlesinger, Philipp and Menzel, Wolfgang}, title = {Using Affordances to Shape the Interaction in a Hybrid Spoken Dialogue System}, series = {Elektronische Sprachsignalverarbeitung 2013 : Tagungsband der 24. Konferenz, Bielefeld, 26. - 28.3.2013 ; [ESSV 2013]}, booktitle = {Elektronische Sprachsignalverarbeitung 2013 : Tagungsband der 24. Konferenz, Bielefeld, 26. - 28.3.2013 ; [ESSV 2013]}, publisher = {TUDpress}, isbn = {978-3-94431-03-4}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:18-228-7-1836}, pages = {12 -- 19}, abstract = {Affordances manifest possibilities of interaction with a spoken dialogsystem. For example, the act of asking a question affords to the recipient thepossibility of answering. In the system we present, the observable act of maneuveringaffords the possibility of controlling a motion. Our system thus uses the affordanceprinciple to shape the interaction: to trigger the usage of instructions that are easyto understand and process, the system gives immediate visual feedback to afforduser commands that can then be reacted upon. This tightening of the interactionloop requires an incremental processing paradigm to allow fast reactions and to beable to alter ongoing system actions. Our system is a hybrid of incremental andnon-incremental processing components, combining conventional, state graph-basedprocessing, which has the advantage of widely available toolkits and well-understooddialog management, with incremental dialog processing which allows for the tightfeedback loop that provides for quick reactions. We tested our approach in a smalluser study and found that users used simpler and setting-independent commandsmore often and were more efficient when faced with the affordance-based version ofour system.}, language = {en} } @book{Baumann, author = {Baumann, Timo}, title = {Incremental Spoken Dialogue Processing: Architecture and Lower-level Components}, publisher = {Bielefeld University}, isbn = {9783848200221}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:361-25819101}, pages = {176}, language = {en} } @article{Richter, author = {Richter, Stefanie}, title = {Integrated Care for People with Dementia}, series = {Geriatrics}, volume = {2}, journal = {Geriatrics}, number = {1}, publisher = {MDPI}, address = {Basel}, doi = {10.3390/geriatrics2010001}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-22091}, pages = {1 -- 13}, abstract = {This article presents results of the social-scientific evaluation of an established care model for people with dementia developed by the professionals as a result of acute problems in care in north-east Germany. In addition to the central elements of the model, the conditions of intersectoral and interprofessional cooperation as well as the qualification profile requirements of the professional groups involved are presented in detail. The results can give suggestions for the organization of integrated care for people with dementia in other countries. Further, the author would hereby like to highlight the gain from the scientific examination of solutions to problems in the field.}, subject = {Demenz}, language = {en} } @article{JiBorrmannBeetzetal., author = {Ji, Yang and Borrmann, Andr{\´e} and Beetz, Jakob and Obergrießer, Mathias}, title = {Exchange of Parametric Bridge Models Using a Neutral Data Format}, series = {Journal of Computing in Civil Engineering}, volume = {27}, journal = {Journal of Computing in Civil Engineering}, number = {6}, publisher = {American Society of Civil Engineers}, address = {Reston, VA}, doi = {10.1061/(asce)cp.1943-5487.0000286}, pages = {593 -- 606}, abstract = {Parametric modeling is a well-established methodology in the field of mechanical engineering. It allows for the creation of flexible geometric models using parameters for dimensions and makes it possible to define numeric relationships between these parameters by means of mathematical formulas and define geometric-topological constraints between geometric entities. The result is a flexible geometric model that can be steered through the manipulation of its primary parameters. In contrast to explicit geometric models with fixed dimensions, a parametric model can capture the design intent and represent domain knowledge. The use of parametric modeling techniques is particularly beneficial for designing bridges. This is because the geometric design of bridges is mainly determined by external constraints resulting from the size and the layout of both the overlying and the undercrossing carriageway. This reduces the effort required for reworking when changes are made, while simultaneously providing a high degree of reusability for the model in other, similar projects, resulting in significantly increased efficiency in the bridge design process. Because of the strong fragmentation of the architecture, engineering, and construction (AEC) industry, the data exchange between the different participants in a construction project is of crucial importance. The use of neutral, open data formats has proved to be the most suitable approach to realize this data exchange. However, currently existing neutral data formats do not allow for an exchange of parametric geometry. To overcome these technical limitations, this paper introduces an extension to the IFC-Bridge format, thus providing a means of interchanging parametric bridge models. This article describes in detail the necessary entities introduced to define parameters and capture dimensional and geometric constraints. The suitability of the developed extensions is proved by presenting the successful transfer of parametric bridge models between two parametric design systems as well as from a design system to a structural analysis system.}, language = {en} } @inproceedings{Hoeller, author = {H{\"o}ller, Christoph}, title = {Review and Comparison of ASTM and ISO Standards on Sound Transmission in Buildings}, series = {Impact of noise control engineering : 47th International Congress and Exposition on Noise Control Engineering (INTERNOISE 2018) : Chicago, Illinois, USA, 26-29 August 2018}, booktitle = {Impact of noise control engineering : 47th International Congress and Exposition on Noise Control Engineering (INTERNOISE 2018) : Chicago, Illinois, USA, 26-29 August 2018}, publisher = {Curran Associates, Inc.}, address = {Red Hook, NY}, language = {en} } @inproceedings{Hoege, author = {H{\"o}ge, Harald}, title = {The Use of Temporal Features in Cortical Segmentation of Syllables}, series = {Elektronische Sprachsignalverarbeitung 2024, Tagungsband der 35. Konferenz, Regensburg, 6.-8. M{\"a}rz 2024}, booktitle = {Elektronische Sprachsignalverarbeitung 2024, Tagungsband der 35. Konferenz, Regensburg, 6.-8. M{\"a}rz 2024}, editor = {Baumann, Timo}, publisher = {TUDpress}, address = {Dresden}, isbn = {978-3-95908-325-6}, doi = {10.35096/othr/pub-7082}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-70823}, pages = {70 -- 77}, abstract = {There is high confidence for the hypothesis that in speech perception the cycles of a θ-oscillation segment the auditory signal into syllables [8]. Yet the functionality of the oscillator generating the θ-oscillation is unknown. We follow the finding that, within an auditory scene, speech is perceived as a stream given by temporal coherence [12]. We work with the hypotheses that the θ-oscillator is driven by temporal features providing this coherence. We propose a new temporal feature called O-distance, which detects the onset of a syllable - the starting point to of a θ-cycle-triggered by the temporal distance from to to the instance of the maximal rise of the loudness curve of the vowel. To extract to from the auditory signal, we use the statistical properties of this distance based on the C-center hypothesis [25], which predicts a close temporal relation of the onset consonants to the onset of a vowel. The statistics are derived from reference O-distance extracted from an articulatory database, where the minima and maxima of the loudness are related to maxima and minima of the lower incisor and tongue tip. To judge the quality of the O-distance extracted from the auditory signal, we regard the temporal deviation of the O-distance to the reference O-distance. Currently we achieve a mean deviation of 34ms.}, language = {en} } @inproceedings{Kruspe, author = {Kruspe, Anna}, title = {More than words: Advancements and Challenges in Speech Recognition for Singing}, series = {Elektronische Sprachsignalverarbeitung 2024, Tagungsband der 35. Konferenz, Regensburg, 6.-8. M{\"a}rz 2024}, booktitle = {Elektronische Sprachsignalverarbeitung 2024, Tagungsband der 35. Konferenz, Regensburg, 6.-8. M{\"a}rz 2024}, editor = {Baumann, Timo}, publisher = {TUDpress}, address = {Dresden}, isbn = {978-3-95908-325-6}, doi = {10.35096/othr/pub-7074}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-70748}, pages = {1 -- 10}, abstract = {This paper addresses the challenges and advancements in speech recognition for singing, a domain distinctly different from standard speech recognition. Singing encompasses unique challenges, including extensive pitch variations, diverse vocal styles, and background music interference. We explore key areas such as phoneme recognition, language identification in songs, keyword spotting, and full lyrics transcription. I will describe some of my own experiences when performing research on these tasks just as they were starting to gain traction, but will also show how recent developments in deep learning and large-scale datasets have propelled progress in this field. My goal is to illuminate the complexities of applying speech recognition to singing, evaluate current capabilities, and outline future research directions.}, language = {en} } @inproceedings{Sering, author = {Sering, Konstantin}, title = {Speech/Non-Speech Classification Slightly Improves Synthesis Quality in PAULE}, series = {Elektronische Sprachsignalverarbeitung 2024, Tagungsband der 35. Konferenz, Regensburg, 6.-8. M{\"a}rz 2024}, booktitle = {Elektronische Sprachsignalverarbeitung 2024, Tagungsband der 35. Konferenz, Regensburg, 6.-8. M{\"a}rz 2024}, editor = {Baumann, Timo}, publisher = {TUDpress}, address = {Dresden}, isbn = {978-3-95908-325-6}, doi = {10.35096/othr/pub-7095}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-70955}, pages = {173 -- 180}, abstract = {One of the tasks PAULE[1, 2] solves is finding suitable control parameter (cp-)trajectories for a given target acoustic. These cp-trajectories can be used to synthesize speech with the articulatory speech synthesizer of the VocalTractLab (VTL) [3]. If the target acoustic contains substantial microphone noise or other background noises, occasionally PAULE optimizes not for the speech in the target, but for this background noises. By adding a speech/non-speech classifier to the feedback and planning-loop in PAULE this resynthesis of background noises should be mitigated. Unfortunately, the improvements were minor, which might be due to uninformative gradients of the classifier. The importance of informative gradients and the use classifiers to adapt PAULE to different tasks are explained and discussed.}, language = {en} } @article{DendorferMaierTayloretal., author = {Dendorfer, Sebastian and Maier, Hans J{\"u}rgen and Taylor, David and Hammer, Joachim}, title = {Anisotropy of the fatigue behaviour of cancellous bone}, series = {Journal of Biomechanics}, volume = {41}, journal = {Journal of Biomechanics}, number = {3}, doi = {10.1016/j.jbiomech.2007.09.037}, pages = {636 -- 641}, abstract = {The fatigue behaviour of materials is of particular interest for the failure prediction of materials and structures exposed to cyclic loading. For trabecular bone structures only a few sets of lifetime data have been reported in the literature and structural measures are commonly not considered. The influence of load contributions which are not aligned with the main physiological axis remains unclear. Furthermore site and species dependent relationships are not well described. In this study five different groups of trabecular bone, defined in terms of orientation, species and site were exposed to cyclic compression. In total, 108 fatigue tests were analysed. The lifetimes were found to decrease drastically when off-axis loads were applied. Additionally, species and site strongly affect fatigue lifetimes. Strains at failure were also found to be a function of orientation.}, subject = {Erm{\"u}dung}, language = {en} } @incollection{DendorferHammerLenich, author = {Dendorfer, Sebastian and Hammer, Joachim and Lenich, Andreas}, title = {Characterisation and testing of biomaterials}, series = {Basic Engineering for Medics and Biologists: An ESEM Primer}, booktitle = {Basic Engineering for Medics and Biologists: An ESEM Primer}, number = {Chapter IV.4.}, editor = {Lee, T. Clive and Niederer, Peter F.}, publisher = {Non Basic Stock Line}, isbn = {978-1607505266}, subject = {Biomaterial}, language = {en} } @article{KellnerUtz, author = {Kellner, Florian and Utz, Sebastian}, title = {Sustainability in supplier selection and order allocation: Combining integer variables with Markowitz portfolio theory}, series = {Journal of Cleaner Production}, volume = {214}, journal = {Journal of Cleaner Production}, publisher = {Springer Nature}, doi = {10.1016/j.jclepro.2018.12.315}, pages = {462 -- 474}, abstract = {This research presents a decision support methodology for the multi-criteria supplier selection and order allocation problem. The proposed approach supports purchasing managers in assembling mid-term supplier portfolios while making them aware of the trade-offs between the supplier sustainability, the purchasing costs, and the overall supply risk. First, we propose a multi-objective optimization model with three objectives: to maximize the supplier sustainability, to select the supplier portfolio with the lowest purchasing costs, and to minimize the supply risk. Our model extends existing mathematical approaches that follow the portfolio theory fathered by H. Markowitz by integrating the aspect 'risk' into the supplier selection problem. Secondly, since we allow for integer variables in our model—in contrast to the classical Markowitz portfolio theory—we use the ε-constraint method to visualize the efficient surface. The possibility of considering the non-dominated set of supplier portfolios is advantageous for purchasing managers as they gain a picture of the different optimal supplier portfolios and are able to analyze the trade-offs between the different purchasing goals before making a decision. Finally, we illustrate the applicability of the proposed methodology in a real-world supplier selection and order allocation case from the automotive industry. In the example case, we identify 1754 optimal supplier portfolios that may be assembled based on the eight available suppliers. Our analyses show that each optimal portfolio consists of two suppliers, with one specific supplier being included in each portfolio. Furthermore, four suppliers are not part of any optimal solution.}, language = {en} } @article{KellnerLienlandUtz, author = {Kellner, Florian and Lienland, Bernhard and Utz, Sebastian}, title = {A multi-criteria decision-making approach for assembling optimal powertrain technology portfolios in low GHG emission environments}, series = {Journal of Industrial Ecology}, volume = {25}, journal = {Journal of Industrial Ecology}, number = {6}, publisher = {Wiley}, doi = {10.1111/jiec.13148}, pages = {1412 -- 1429}, abstract = {Environmental regulations force car manufacturers to renew the powertrain technology portfolio offered to the customer to comply with greenhouse gas (GHG) emission targets. In turn, automotive companies face the task of identifying the "right" powertrain technology portfolio consisting of, for example, internal combustion engines and electric vehicles, because the selection of a particular powertrain technology portfolio affects different company targets simultaneously. What makes this decision even more challenging is that future market shares of the different technologies are uncertain. Our research presents a new decision-support approach for assembling optimal powertrain technology portfolios while making decision-makers aware of the trade-offs between the achievable profit, the achievable market share, the market share risk, and the GHG emissions generated by the selected vehicle fleet. The proposed approach combines "a posteriori" decision-making with multi-objective optimization. In an application case, we feed the outlooks of selected market studies into the proposed decision-support system. The result is a visualization and analysis of the current real-world decision-making problem faced by many automotive companies. Our findings indicate that for the proposed GHG restriction at work in 2030 in the European Union, no optimal powertrain technology portfolio with less than 35\% of vehicles equipped with an electric motor exists.}, language = {en} } @article{Lienland, author = {Lienland, Bernhard}, title = {The Implementation of a Cash-Flow-Based Mathematical R\&D Project Selection Model}, series = {International Journal of Information Technology Project Management (IJITPM)}, volume = {7}, journal = {International Journal of Information Technology Project Management (IJITPM)}, number = {3}, publisher = {IGI Global}, doi = {10.4018/IJITPM.2016070102}, pages = {22}, abstract = {Customer project selection is a challenge for many industrial companies. An inappropriate project selection approach can lead to constraint violations, high fixed costs, and suboptimal portfolios. To overcome these problems a cash-flow-based linear optimization model was developed in partnership with a tier-1 automotive supplier. Implementation barriers had been verified through a case study conducted at two organizational hierarchies. Results suggest that an application at the operating levels is possible. At higher levels, though, product and firm complexity require major implementation efforts. This article serves theorists as well as practitioners in multiple regards. First, an overview of existing project selection methods and their application in practice is provided. Additionally, the supplier's current appraisal process is depicted. Second, operations research implementation barriers are identified and validated for the adoption of the proposed mathematical project selection approach. Third, a guideline including procedures to overcome experienced difficulties is presented.}, language = {en} } @article{NeumuellerLaschKellner, author = {Neum{\"u}ller, Claudia and Lasch, Rainer and Kellner, Florian}, title = {Integrating sustainability into strategic supplier portfolio selection}, series = {Management decision}, volume = {54}, journal = {Management decision}, number = {1}, publisher = {Emerald}, doi = {10.1108/MD-05-2015-0191}, pages = {194 -- 221}, abstract = {Purpose - The purpose of this paper is to propose a comprehensive methodology and a problem-specific model for the configuration of the optimal strategic supplier portfolio in terms of traditional, performance-related objectives and sustainability targets. Design/methodology/approach - To bridge the research gap, i.e., to align strategic supplier portfolio selection with corporate sustainability targets, a hybrid model of the analytic network process (ANP) and goal programming (GP) is developed. To validate the model, a case example is presented and managerial feedback is collected. Findings - By enabling the integration of sustainability targets into strategic supplier portfolio configuration, the hybrid ANP-GP model contributes to research in the area of sustainable supply chain management. Results indicate that simplifying the model by omitting one or more details may lead to unfortunate actions. Research limitations/implications - The model has been applied using a case example in the automotive industry. To strengthen the findings, it should be examined under other terms as well. Practical implications - Integrating economic, environmental, and social targets into strategic supplier portfolio configuration reduces supply risks and promotes the achievement of the sustainability goals of the purchasing company. Social implications - Strategic supplier selection counts among the decisions that have an impact on the environment and society for several years. Configuring economically rational, environmentally friendly, and socially responsible supplier bases supports worldwide efforts towards sustainable development. Originality/value - Although sustainable supplier selection has gained importance in recent years, this is the first time that a comprehensive model for the determination of the optimal strategic supplier portfolio in terms of performance-related objectives and sustainability targets has been proposed.}, language = {en} } @unpublished{KellnerLienlandUtz, author = {Kellner, Florian and Lienland, Bernhard and Utz, Sebastian}, title = {An a Posteriori Multi-Objective Supplier Portfolio Selection Approach Under Risk and Sustainability Considerations}, series = {SSRN Electronic Journal}, journal = {SSRN Electronic Journal}, doi = {10.2139/ssrn.2901390}, pages = {39}, abstract = {This research presents a novel, state-of-the-art methodology for solving the multi-criteria supplier selection problem under risk and sustainability considerations. The approach combines multi-objective optimization with the analytic network process to meet the requirements for supplier portfolio configuration with sustainability considerations. To integrate the aspect 'risk' into the supplier selection problem, this research develops a multi-objective optimization model based on the investment portfolio theory introduced by Markowitz. The proposed model is a non-standard portfolio selection problem with four objectives: to minimize the purchasing costs, to select the supplier portfolio with the highest logistics service, to minimize the supply risk, and to order as much as possible from those suppliers with outstanding sustainability performance. The optimization model, which has three linear and one quadratic objective function, is solved by an algorithm which analytically computes a set of efficient solutions and provides graphical decision support by a visualization of the complete and exactly-computed Pareto front (a posteriori approach). The possibility of computing all Pareto optimal supplier portfolios is beneficial for decision makers as they can compare all optimal solutions at once, identify the trade-offs between the criteria, and study how the different aspects of supplier portfolio configuration may be balanced to finally choose the composition that satisfies the purchasing company's strategy at best. The approach has been applied to a real-world supplier portfolio configuration case to demonstrate its applicability and to analyze how the consideration of sustainability requirements may affect the traditional supplier selection and purchasing goals in a real-life setting.}, language = {en} } @article{KellnerIgl, author = {Kellner, Florian and Igl, Johannes}, title = {Greenhouse gas reduction in transport: analyzing the carbon dioxide performance of different freight forwarder networks}, series = {Journal of Cleaner Production}, volume = {99}, journal = {Journal of Cleaner Production}, publisher = {Elsevier}, doi = {10.1016/j.jclepro.2015.03.026}, pages = {177 -- 191}, abstract = {There are growing concerns in the food industry about how supply chains can be managed in a more sustainable way. When distribution activities are outsourced to a logistics service provider (LSP), shippers need to evaluate the LSPs they may (potentially) engage in order to ensure that supply chain sustainability goals are met. In this paper, we present a methodology for LSP evaluation and focus on the ecological dimension of sustainability. We examine how the network carbon footprint of a real-world distribution system is affected by the LSP network that is chosen to forward goods from production facilities to customers. To do this, we analyze the shipment data of an existing Fast Moving Consumer Goods (FMCG) manufacturer. A quantitative distribution network model is set up to study the network carbon footprint of 125 scenarios. Real-world shipments are forwarded via five generic, idealized types of LSP networks. In total, 625 network carbon footprints, specified by three distribution logistics variables and the structure of the LSP network, have been calculated. The results show that LSP structures practicing a geographically decentralized consolidation of shipments are most efficient in reducing of greenhouse gas (GHG) emissions. Furthermore, the effects of changing the manufacturer's and the LSP's strategies for deciding on the tonnage to be forwarded via the LSP network or moved by direct transports are quantified. Finally, we estimate the GHG effect of improving the capacity utilization of the vehicles that move the products.}, language = {en} } @article{Kellner, author = {Kellner, Florian}, title = {Generating greenhouse gas cutting incentives when allocating carbon dioxide emissions to shipments in road freight transportation}, series = {OR Spectrum}, volume = {44}, journal = {OR Spectrum}, number = {3}, publisher = {Springer Nature}, doi = {10.1007/s00291-022-00675-y}, pages = {833 -- 874}, abstract = {Road freight transportation accounts for a great share of the anthropogenic greenhouse gas (GHG) emissions. In order to provide a common methodology for carbon accounting related to transport activities, the European Committee for Standardization has published the European Norm EN-16258. Unfortunately, EN-16258 contains gaps and ambiguities and leaves room for interpretation, which makes the comparison of the environmental performance of different logistics networks still difficult and hinders the identification of best practices. This research contributes to the identification of particularly meaningful principles for the allocation of GHG to shipments in road freight transportation by presenting an analytical framework for studying the performance of the EN-16258 allocation schemes with respect to accuracy, fairness, and the GHG minimizing incentive. In doing so, we continue previous studies that analyzed two important aspects of the EN-16258 allocation rules: accuracy and fairness. This study provides further insights into this allocation problem by investigating the incentive power of the different allocation schemes to opt for the GHG minimal way of running a road freight network. First, we complement the list of transport scenarios introduced in prior studies and present two novel scenarios. Second, we carry out a series of numerical experiments to compare the EN-16258 allocation rules with respect to accuracy, fairness, and the GHG minimizing incentive. We find that the results may differ significantly for the two scenarios, suggesting a case-by-case recommendation. This is particularly interesting because the first scenario confirms the results of the prior studies, while the second scenario rather contradicts them.}, language = {en} } @unpublished{KellnerSchneiderbauer, author = {Kellner, Florian and Schneiderbauer, Miriam}, title = {Further Insights into the Allocation of Greenhouse Gas Emissions to Shipments in Road Freight Transportation: The Pollution Routing Game}, series = {SSRN Electronic Journal}, journal = {SSRN Electronic Journal}, doi = {10.2139/ssrn.3221764}, abstract = {At present, there is no globally accepted standard for the allocation of greenhouse gas (GHG) emissions to shipments in road freight transportation. The only official international standard for emission calculation of transport operations is the European Norm EN-16258. However, even this norm still allows choosing from several alternative emission allocation schemes. This research aims to harmonize the process of GHG declarations for supply chains by identifying among all allocation units specified by EN-16258 the one that describes a shipment's contribution to GHG emissions best. For this purpose, concepts of the cooperative game theory are used. First, we develop three transport scenarios that allow studying a shipment's effect on GHG: a vehicle routing problem, a network flow model, and a mixed scenario. Our approach extends previous research projects because we take into account that shipment characteristics in terms of origin, destination, weight, and volume consume transport capacities to different degrees, impact the routing of the commercial vehicles and, thus, determine GHG. Second, we present the results of a computational study that bases on the introduced transport scenarios and that compares the allocation vectors resulting from the EN-16258 allocation rules with the Shapley value, which serves as a benchmark for a shipment's contribution to GHG. Furthermore, we show how often the EN-16258 allocation principles are in line with a set of game theoretical fairness criteria. The results indicate that the allocation unit 'distance' is the closest to the game theory benchmark and most often in line with game theoretical fairness criteria.}, language = {en} } @article{FuchsBeckLienlandetal., author = {Fuchs, Christoph and Beck, Daniel and Lienland, Bernhard and Kellner, Florian}, title = {The role of IT in automotive supplier supply chains}, series = {Journal of Enterprise Information Management}, volume = {31}, journal = {Journal of Enterprise Information Management}, number = {1}, publisher = {emerald insight}, doi = {10.1108/JEIM-03-2017-0038}, pages = {64 -- 88}, abstract = {Purpose The purpose of this paper is to explore the impact of information technology (IT) on supply chain performance in the automotive industry. Prior studies that analyzed the impact of IT on supply chain performance report results representing the situation of the "average industry." This research focuses on the automotive industry because of its major importance in many national economies and due to the fact that automotive supply chains do not represent the supply chain of the average industry. Design/methodology/approach A research model is proposed to examine the relationships between IT capabilities, supply chain capabilities, and supplier performance. The model divides IT capabilities into functional and data capabilities, and supply chain capabilities into internal process excellence and information sharing. Data have been collected from 343 automotive first-tier suppliers. Structural equation modeling with partial least squares is used to analyze the data. Findings The results suggest that functional capabilities have the greatest impact on internal process excellence, which in turn enhances supplier performance. However, frequent and adequate information sharing also contributes significantly to supplier performance. Data capabilities enable supply chain capabilities through their positive impact on functional capabilities. Practical implications The findings will help managers to understand the effect of IT implementation on company performance and to decide whether to invest in the expansion of IT capacities. Originality/value This research reports the impact of IT on supply chain performance in one of the most important industries in many industrialized countries, and it provides a new perspective on evaluating the contribution of IT on firm performance.}, language = {en} } @article{LienlandBaumgartnerKnubben, author = {Lienland, Bernhard and Baumgartner, Alexander and Knubben, Evelyn}, title = {The undervaluation of corporate reputation as a supplier selection factor}, series = {Journal of Purchasing and Supply Management}, volume = {19}, journal = {Journal of Purchasing and Supply Management}, number = {2}, publisher = {Elsevier}, issn = {1478-4092}, doi = {10.1016/j.pursup.2013.04.001}, pages = {84 -- 97}, abstract = {Prior research studies on supplier selection factors assess vendor reputation as a low ranked criterion. Reputation in these articles, however, only refers to the position in the industry, without considering the role of the final customer. Our results from a survey with 565 individuals suggest that the end user as a stakeholder should be also considered when analyzing a vendor's prestige. We demonstrate that a supplier's standing has negative as well as positive reputational effects on the buyer. Depending on the relevance of the purchased good as well as the reputation of the supplier and the buyer, low/high-ranked ingredients significantly decrease/increase the final customer's perception of the buyer.}, language = {en} } @article{Kellner, author = {Kellner, Florian}, title = {Exploring the impact of urbanization on consumer goods distribution networks}, series = {Journal of Asian Business and Economic Studies}, volume = {28}, journal = {Journal of Asian Business and Economic Studies}, number = {2}, publisher = {Emerald}, doi = {10.1108/JABES-12-2019-0127}, pages = {101 -- 120}, abstract = {Purpose Due to the growing percentage share of urban dwellers, the physical distribution of products faces altering conditions. This research explores the effects that urbanization has on the performance of a fast-moving consumer goods distribution network. A focus is set on changes in distribution cost, the cost-minimal network design, and greenhouse gas emissions. Design/methodology/approach The analyses are based on a quantitative distribution network model of an existing manufacturer of consumer goods. Findings The results indicate that the foreseen population shift will affect the network's economic and environmental performance. Effects are, among others, due to differences in the efficiency of supplying urban and nonurban regions. The combined effects of urbanization and the development of the population size will even more affect the network's performance. Originality/value Research dealing with distribution logistics and urbanization primarily focuses on city logistics. In this paper, the object of analysis is the entire distribution system.}, language = {en} } @article{NeumuellerKellnerGuptaetal., author = {Neum{\"u}ller, Claudia and Kellner, Florian and Gupta, Jatinder N.D. and Lasch, Rainer}, title = {Integrating three-dimensional sustainability in distribution centre selection: the process analysis method-based analytic network process}, series = {International Journal of Production Research}, volume = {53}, journal = {International Journal of Production Research}, number = {2}, publisher = {Taylor \& Francis}, doi = {10.1080/00207543.2014.939241}, pages = {409 -- 434}, abstract = {In this paper, we propose a combined methodology for the selection of distribution centres (DCs) by integrating and balancing economic, environmental and social sustainability aspects. The analytic network process (ANP) permits to systematically evaluate possible DCs on the basis of a situation-specific decision structure. A systematic development of the decision networks, which is one of the core challenges using the ANP, is supported by the process analysis method which we extend for that purpose. The validity and soundness of the proposed framework are demonstrated by means of a case study. The case study results reveal that omitting aspects of sustainability can lead to unfortunate results.}, language = {en} } @article{Kellner, author = {Kellner, Florian}, title = {Insights into the effect of traffic congestion on distribution network characteristics - a numerical analysis based on navigation service data}, series = {International Journal of Logistics Research and Applications}, volume = {19}, journal = {International Journal of Logistics Research and Applications}, number = {5}, publisher = {Taylor \& Francis}, doi = {10.1080/13675567.2015.1094043}, pages = {395 -- 423}, abstract = {This research studies effects that the average increase in travel times due to road traffic congestion has on characteristics of an existing distribution network. It presents the most detailed estimate of 'on-the-road' effects on distribution network characteristics up to now, from the network modelling perspective and from the processed data point of view. A concrete network model allowing for the representation of all relevant transportation flows is presented. The processed traffic information relies on navigation service data. The use of such data allows the requirements that arise for the traffic analysis of a whole distribution network to be met. It is shown that this data source may considerably contribute in forthcoming research. The effects of traffic congestion are quantified to get insights into the extent to which regular traffic congestion affects distribution network characteristics and to understand the mitigating effect when the number of distribution centres is increased.}, language = {en} } @article{Kellner, author = {Kellner, Florian}, title = {Allocating greenhouse gas emissions to shipments in road freight transportation: Suggestions for a global carbon accounting standard}, series = {Energy Policy}, volume = {98}, journal = {Energy Policy}, address = {Elsevier}, doi = {10.1016/j.enpol.2016.09.030}, pages = {565 -- 575}, abstract = {The European Norm EN 16258 was published in 2012 to provide a common methodology for the calculation and declaration of energy consumption and greenhouse gas emissions related to any transport operation. The objective was to offer a pragmatic and scientifically-acceptable approach that allows a wide group of users to prepare standardized, accurate, credible, comparable, and verifiable energy consumption and emission declarations. However, in its current form, EN 16258 contains gaps and ambiguities, and leaves room for interpretation, which makes comparisons of supply chains difficult. This research aims to overcome the shortcomings in the domain of allocating emissions from road freight transport operations to single shipments. Based on a discussion of emission drivers and the results of numerical experiments comparing the allocation vectors created by the EN 16258 allocation rules with those generated by the Shapley value, which is claimed to be the benchmark, 'distance' is identified as the single most useful unit for bridging the trade-off between accuracy and simplicity better than the other recommended allocation schemes. Thus, this paper claims that future versions of EN 16258 should only allow the allocation unit 'distance.' This will promote the accurateness, simplicity, consistency, transparency, and comparability of emission declarations.}, language = {en} } @article{KellnerUtz, author = {Kellner, Florian and Utz, Sebastian}, title = {An inverse optimization approach for studying sustainability preferences in sourcing decisions}, series = {Journal of Cleaner Production}, volume = {483}, journal = {Journal of Cleaner Production}, publisher = {Elsevier}, doi = {10.1016/j.jclepro.2024.144305}, abstract = {Throughout many societies around the globe, there is growing awareness of the urgent need for the transition towards a sustainable economy. Research shows that buying firms have substantial leverage to initiate sustainable development by controlling the sustainable performance of their suppliers. In that context, this article presents a novel methodology based on inverse optimization to derive the implicit preferences of decision-makers in the trade-off between traditional sourcing objectives and sustainability in the supplier selection and order allocation process. The derived implicit preferences can then be used for further analyses to gain a better understanding of the characteristics of purchasing managers and sourcing situations that come with particularly high/low preferences placed on sustainability. Since the inverse optimization approach is computationally resource-intensive and consumes a significant amount of time, we present a scalable state-of-the-art cloud architecture that allows solving an arbitrary number of optimization programs in an acceptable amount of time. We demonstrate the feasibility of the proposed methodology in a real-world case. In doing so, we test how important sustainability aspects are in the supplier selection and order allocation decisions of one of the world's largest automotive parts manufacturers.}, language = {en} } @article{BraunKunklerKellner, author = {Braun, Maximilian and Kunkler, Jan and Kellner, Florian}, title = {Towards Sustainable Cities: Utilizing Floating Car Data to Support Location-Based Road Network Performance Measurements}, series = {Sustainability}, volume = {12}, journal = {Sustainability}, number = {19}, publisher = {MDPI}, doi = {10.3390/su12198145}, abstract = {Road network performance (RNP) is a key element for urban sustainability as it has a significant impact on economy, environment, and society. Poor RNP can lead to traffic congestion, which can lead to higher transportation costs, more pollution and health issues regarding the urban population. To evaluate the effects of the RNP, the involved stakeholders need a real-world data base to work with. This paper develops a data collection approach to enable location-based RNP analysis using publicly available traffic information. Therefore, we use reachable range requests implemented by navigation service providers to retrieve travel times, travel speeds, and traffic conditions. To demonstrate the practicability of the proposed methodology, a comparison of four German cities is made, considering the network characteristics with respect to detours, infrastructure, and traffic congestion. The results are combined with cost rates to compare the economical dimension of sustainability of the chosen cities. Our results show that digitization eases the assessment of traffic data and that a combination of several indicators must be considered depending on the relevant sustainability dimension decisions are made from.}, language = {en} } @article{ObermaierHofmannKellner, author = {Obermaier, Robert and Hofmann, Johann and Kellner, Florian}, title = {Webbasierte Fertigungssteuerung in der Praxis: Pruduktivit{\"a}tssteigerungen mit dem Manufacturing-Execution-Sytem MR-CM©}, series = {HMD Praxis der Wirtschaftsinformatik}, volume = {47}, journal = {HMD Praxis der Wirtschaftsinformatik}, number = {2}, publisher = {Springer Nature}, doi = {10.1007/BF03340455}, pages = {49 -- 59}, abstract = {Manufacturing-Execution-Systeme (MES) werden in der Fertigungsindustrie dazu eingesetzt, einen durchgehenden Informationsfluss zwischen den an der Fertigung beteiligten Systemen herzustellen. Von der Vernetzung aller an der Produktion beteiligten Systeme wird dabei eine gesteigerte Produktivit{\"a}t auf Shop-Floor-Ebene erwartet. Beim Durchlauf des beispielhaft gezeigten Fertigungsauftrages wurden durch den Einsatz von MR-CM©, einem von der Maschinen-fabrik Reinhausen entwickelten und implemen-tierten MES, bereits einige Produktivit{\"a}tspotenziale im Vergleich mit der konventionellen Abwicklung ohne Einsatz des MES deutlich. Diese resultieren im Wesentlichen aus der Eliminierung von nicht wertsch{\"o}pfenden Schnittstellenproblemen zwischen den an der Auftragsdurchf{\"u}hrung beteiligten Maschinen. Die erzielten Produktivit{\"a}tszuw{\"a}chse bestehen im Kern aus einer Verk{\"u}rzung der Maschinenr{\"u}stzeiten, was zu einer Reduktion der Produktionskosten und einer Zunahme der Produktionsflexibilit{\"a}t f{\"u}hrt und zu einer Reduzierung der Werkzeugbest{\"a}nde sowie der damit verbundenen Kapitalbindungskosten.}, language = {en} } @article{KunklerBraunKellner, author = {Kunkler, Jan and Braun, Maximilian and Kellner, Florian}, title = {Speed Limit Induced CO2 Reduction on Motorways: Enhancing Discussion Transparency through Data Enrichment of Road Networks}, series = {Sustainability}, volume = {13}, journal = {Sustainability}, number = {1}, publisher = {MDPI}, doi = {10.3390/su13010395}, abstract = {Considering climate change, recent political debates often focus on measures to reduce CO2 emissions. One key component is the reduction of emissions produced by motorized vehicles. Since the amount of emission directly correlates to the velocity of a vehicle via energy consumption factors, a general speed limit is often proposed. This article presents a methodology to combine openly available topology data of road networks from OpenStreetMap (OSM) with pay-per-use API traffic data from TomTom to evaluate such measures transparently by analyzing historical real-world circumstances. From our exemplary case study of the German motorway network, we derive that most parts of the motorway network on average do not reach their maximum allowed speed throughout the day due to traffic, construction sites and general road utilization by network participants. Nonetheless our findings prove that the introduction of a speed limit of 120 km per hour on the German autobahn would restrict 50.74\% of network flow kilometers for a CO2 reduction of 7.43\% compared to the unrestricted state.}, language = {en} } @article{LienlandZeng, author = {Lienland, Bernhard and Zeng, Li}, title = {A Review and Comparison of Genetic Algorithms for the 0-1 Multidimensional Knapsack Problem}, series = {International Journal of Operations Research and Information Systems (IJORIS)}, volume = {6}, journal = {International Journal of Operations Research and Information Systems (IJORIS)}, number = {2}, publisher = {IGI Global}, issn = {1947-9328}, doi = {10.4018/ijoris.2015040102}, pages = {11}, abstract = {The 0-1 multidimensional knapsack problem (MKP) is a well-known combinatorial optimization problem with several real-life applications, for example, in project selection. Genetic algorithms (GA) are effective heuristics for solving the 0-1 MKP. Multiple individual GAs with specific characteristics have been proposed in literature. However, so far, these approaches have only been partially compared in multiple studies with unequal conditions. Therefore, to identify the "best" genetic algorithm, this article reviews and compares 11 existing GAs. The authors' tests provide detailed information on the GAs themselves as well as their performance. The authors validated fitness values and required computation times in varying problem types and environments. Results demonstrate the superiority of one GA.}, language = {en} } @article{KempfLauerCorstenetal., author = {Kempf, Sabrina and Lauer, Norina and Corsten, Sabine and Voigt-Radloff, Sebastian}, title = {Potential analysis of research on speech therapy-led communication training in aphasia following stroke}, series = {Zeitschrift f{\"u}r Evidenz, Fortbildung und Qualitat im Gesundheitswesen}, volume = {108}, journal = {Zeitschrift f{\"u}r Evidenz, Fortbildung und Qualitat im Gesundheitswesen}, number = {1, Suppl. 1}, publisher = {Elsevier}, doi = {10.1016/j.zefq.2014.08.002}, pages = {45 -- 52}, abstract = {Health problem: In Germany, about 100,000 people currently suffer from aphasia. This speech disorder occurs as a result of neurologic events such as stroke or traumatic brain injury. Aphasia causes major limitations in social participation and quality of life and can be associated with unemployability and social isolation. For affected persons, it is essential to regain and maintain autonomy in daily life, both at work and with family and friends. The loss of autonomy is perceived much more dramatically than the loss of speech. Clients wish to minimise this loss of autonomy in daily life. As full recovery is not achievable in chronic aphasia, treatment must focus on improved compensatory approaches and on supporting the clients' coping strategies. Evidence base: Based on eight randomised comparisons including 347 participants, a recent Cochrane review (Brady et al., 2012) revealed that speech therapy - as compared with no treatment - had positive effects on functional communication in clients suffering from aphasia (0.30 SMD; 95\% CI[0.08 to 0.52]). There was no evidence suggesting that one type of training was superior to the others. However, quality of life and social participation were not evaluated as outcomes. Recent studies found that speech therapy-led training for communication and self-efficacy and the integration of communication partners may have a positive impact on these client-centred outcomes. Implication for research: Speech therapy-led training for communication within a group setting should be manualised and pilot-tested with respect to feasibility and acceptance in a German sample of people with aphasia and their communication partners. Instruments measuring quality of life and social participation can be validated within the scope of this feasibility study. These research efforts are necessary to prepare a large-scale comparative effectiveness research trial comparing the effects of both usual speech therapy and speech therapy-led group communication training on quality of life and social participation.}, language = {en} } @article{KellnerSchneiderbauer, author = {Kellner, Florian and Schneiderbauer, Miriam}, title = {Further insights into the allocation of greenhouse gas emissions to shipments in road freight transportation: The pollution routing game}, series = {European Journal of Operational Research}, volume = {278}, journal = {European Journal of Operational Research}, number = {1}, publisher = {Elsevier}, doi = {10.1016/j.ejor.2019.04.007}, pages = {296 -- 313}, abstract = {At present, there is no globally accepted standard for the allocation of greenhouse gas (GHG) emissions to shipments in road freight transportation. The only official international standard for emission calculation of transport operations is the European Norm EN-16258. However, even this norm still allows choosing from several alternative emission allocation schemes. This research aims to harmonize the process of GHG declarations for supply chains by identifying among all allocation units specified by EN-16258 the one that describes a shipment's contribution to GHG emissions best. For this purpose, concepts of the cooperative game theory are used. First, we develop three transport scenarios that allow studying a shipment's effect on GHG: a vehicle routing problem, a network flow model, and a mixed scenario. Our approach extends previous research projects because we take into account that shipment characteristics in terms of origin, destination, weight, and volume consume transport capacities to different degrees, impact the routing of the commercial vehicles and, thus, determine GHG. Second, we present the results of a computational study that bases on the introduced transport scenarios and that compares the allocation vectors resulting from the EN-16258 allocation rules with the Shapley value, which serves as a benchmark for a shipment's contribution to GHG. Furthermore, we show how often the EN-16258 allocation principles are in line with a set of game theoretical fairness criteria. The results indicate that the allocation unit 'distance' is the closest to the game theory benchmark and most often in line with game theoretical fairness criteria.}, language = {en} } @incollection{KellnerLienlandUtz, author = {Kellner, Florian and Lienland, Bernhard and Utz, Sebastian}, title = {Optimal engine technology mix in a low carbon economy}, series = {2020 International Conference on Decision Aid Sciences and Application (DASA), 08-09 November 2020, Sakheer, Bahrain}, booktitle = {2020 International Conference on Decision Aid Sciences and Application (DASA), 08-09 November 2020, Sakheer, Bahrain}, publisher = {IEEE}, address = {Piscataway, NJ}, isbn = {978-1-7281-9677-0}, doi = {10.1109/DASA51403.2020.9317094}, pages = {95 -- 98}, abstract = {Environmental regulations force automotive companies to modify the powertrain technology portfolio offered to the customer to comply with greenhouse gas (GHG) emission targets. Automotive companies, in turn, are faced with the decision of finding the right powertrain technology portfolio because the selection of a particular technology portfolio affects different company targets at the same time. What makes this decision even more interesting is the fact that future market shares of the different technologies are uncertain. With its numerous objectives, this challenge requires multi-criteria decision-making techniques to identify the optimal powertrain technology portfolio. The objective of this research is to present a new decision support approach for assembling optimal powertrain technology portfolios while making decision-makers aware of the trade-offs between the achievable market share, the market share risk, and the GHG emissions generated by the selected vehicle fleet. The proposed approach combines `a posteriori' decision-making, multi-objective optimization, and the Markowitz portfolio theory. In an application case, the outlooks of selected market studies are fed into the proposed decision support system. The result is a visualization and analysis of the current real-world decision-making problem faced by many automotive companies. Interesting findings of this research include that for the assumed GHG restrictions in place in 2030, there exists no optimal powertrain technology portfolio that is not composed of at least 20\% of electric vehicles.}, language = {en} } @article{KellnerOttoBrabaender, author = {Kellner, Florian and Otto, Andreas and Brab{\"a}nder, Christian}, title = {Bringing infrastructure into pricing in road freight transportation - A measuring concept based on navigation service data}, series = {Transportation Research Procedia}, volume = {25}, journal = {Transportation Research Procedia}, publisher = {Elsevier}, doi = {10.1016/j.trpro.2017.05.458}, pages = {794 -- 805}, abstract = {Differences in road infrastructure, such as capacity, congestion, speed limits affect the productivity and the costs of short-distance freight operations. This article introduces a novel methodology that is based on navigation service data to measure the effects in terms of cost per kilometer using navigation and shipment data. The methodology is applied to five terminals of a forwarding cooperation and has been able to document significant differences in cost per kilometer across the terminals. The research results can be used by logistics service providers to better understand how productivity and thus profitability is affected by the quality of the transportation infrastructure in the particular areas they operate in. Furthermore, the insights will help these companies for better, i.e. cost-based pricing and will allow to document why and where prices need to be adapted.}, language = {en} } @article{KellnerLienlandUtz, author = {Kellner, Florian and Lienland, Bernhard and Utz, Sebastian}, title = {An a posteriori decision support methodology for solving the multi-criteria supplier selection problem}, series = {European Journal of Operational Research}, volume = {272}, journal = {European Journal of Operational Research}, number = {2}, publisher = {Springer}, doi = {10.1016/j.ejor.2018.06.044}, pages = {505 -- 522}, abstract = {This research presents a novel, state-of-the-art methodology for solving a multi-criteria supplier selection problem considering risk and sustainability. It combines multi-objective optimization with the analytic network process to take into account sustainability requirements of a supplier portfolio configuration. To integrate 'risk' into the supplier selection problem, we develop a multi-objective optimization model based on the investment portfolio theory introduced by Markowitz. The proposed model is a non-standard portfolio selection problem with four objectives: (1) minimizing the purchasing costs, (2) selecting the supplier portfolio with the highest logistics service, (3) minimizing the supply risk, and (4) ordering as much as possible from those suppliers with outstanding sustainability performance. The optimization model, which has three linear and one quadratic objective function, is solved by an algorithm that analytically computes a set of efficient solutions and provides graphical decision support through a visualization of the complete and exactly-computed Pareto front (a posteriori approach). The possibility of computing all Pareto-optimal supplier portfolios is beneficial for decision makers as they can compare all optimal solutions at once, identify the trade-offs between the criteria, and study how the different objectives of supplier portfolio configuration may be balanced to finally choose the composition that satisfies the purchasing company's strategy best. The approach has been applied to a real-world supplier portfolio configuration case to demonstrate its applicability and to analyze how the consideration of sustainability requirements may affect the traditional supplier selection and purchasing goals in a real-life setting.}, language = {en} } @article{IglKellner, author = {Igl, Johannes and Kellner, Florian}, title = {Exploring greenhouse gas reduction opportunities for retailers in Fast Moving Consumer Goods distribution networks}, series = {Transportation Research Part D: Transport and Environment}, volume = {50}, journal = {Transportation Research Part D: Transport and Environment}, publisher = {Elsevier}, doi = {10.1016/j.trd.2016.10.008}, pages = {55 -- 69}, abstract = {This research explores logistics-related leverages in the responsibility of retailers for improving the environmental performance of a Fast Moving Consumer Goods (FMCG) distribution network. We examine opportunities for modifying the network carbon footprint by changing network design variables. To do so, a quantitative distribution network model is established, and 150 scenarios are calculated by modifying real-world shipment data from an existing multinational FMCG manufacturer. Four distribution variables are identified for a many-to-many and a hub-and-spoke network structure. Two variables affect the distribution network and two interfere in the shipment structure by manipulating weight and/or the delivery date. This research sheds light on the extent of the changes in greenhouse gas (GHG) emissions of the distribution network that result from modifications in the logistics variables. The greatest effect on the quantity of GHG emissions can be observed when an anticipation horizon for orders is introduced. When shipments are consolidated and delivered only weekly or biweekly from the manufacturer to the retailers, GHG emissions drop significantly. Another opportunity for retailers to cut down GHG emissions is based on the concept of minimum order quantities where shipments to a retailer location are bundled until a certain weight is reached. Additionally, total GHG emissions of distribution may be reduced by raising the tonnage limit, thereby triggering direct shipments between the manufacturer's facilities and the retailer locations, or by raising the tonnage limit, which triggers direct shipments in the logistics service provider network. The extent of GHG reduction is assessed for all investigated variables.}, language = {en} } @article{KellnerIgl, author = {Kellner, Florian and Igl, Johannes}, title = {Estimating the effect of changing retailing structures on the greenhouse gas performance of FMCG distribution networks}, series = {Logistics Research}, volume = {4}, journal = {Logistics Research}, number = {3-4}, publisher = {Springer Nature}, doi = {10.1007/s12159-012-0063-3}, pages = {87 -- 99}, abstract = {The assessment of greenhouse gas (GHG) emissions of supply chain activities is performed to create transparency across the supply chain and to identify emission-cutting opportunities. Literature provides several generic and case study approaches to estimate GHG emissions. But research often focuses on products. This paper sheds light on how the greenhouse performance of a fast-moving consumer goods (FMCG) distribution network depends on several (FMCG specific) variables to set up a "CO2 network footprint". Within a quantitative computational study, the distribution network footprint of an existing FMCG manufacturer is analyzed. Three options being fundamentally able to reduce total GHG emissions are identified: number of distribution centers, performance of the engaged logistics service provider and shipment structure. First, transportation processes for the investigated FMCG manufacturer are analyzed to derive GHG emissions caused by different distribution shipments. Second, initial data are manipulated to simulate variable changes, that is, different logistics structures. Third, results are reported and analyzed to show up how different changes in logistics structures may reduce GHG, without technological propulsion or use of regenerative energy.}, language = {en} } @article{Kellner, author = {Kellner, Florian}, title = {Exploring the impact of traffic congestion on CO2 emissions in freight distribution networks}, series = {Logistics Research}, volume = {9}, journal = {Logistics Research}, publisher = {Springer Nature}, doi = {10.1007/s12159-016-0148-5}, abstract = {This research quantifies the impact that regular road traffic congestion has on the CO2 emissions of a real-world distribution network, and it studies the consequences when the number of distribution centers changes. For this purpose, this study makes use of a network model allowing for a detailed representation of all relevant transport operations, including production flows between factories and distribution centers, line haul shipments between distribution centers and customers, and round/delivery trips between transshipment points and retailer locations for the last mile. The processed trip and traffic information does not rely on standard traffic data collection approaches, such as interviews, in situ technologies, or floating car data, but the road traffic data are retrieved from an online navigation service, such as Bing Maps, Google Maps, Inrix, Here, and TomTom. This study proves that online navigation services may considerably contribute to future research projects analyzing CO2 sensitivities and greenhouse gas cutting opportunities in logistics networks.}, language = {en} } @article{KraftQuaysonKellner, author = {Kraft, Sarah Katharina and Quayson, Matthew and Kellner, Florian}, title = {Assessing the German Act on Corporate Due Diligence Obligations in Supply Chains: a perspective from the smallholder cocoa farmer}, series = {Frontiers in Sustainability}, volume = {5}, journal = {Frontiers in Sustainability}, publisher = {frontiers}, doi = {10.3389/frsus.2024.1376619}, abstract = {This research examines the potential outputs, outcomes, and impacts of the German Act on Corporate Due Diligence Obligations in Supply Chains (LkSG) on the smallholder cocoa farmers in West Africa. The study primarily relies on a literature review and an impact pathway to conduct a systematic analysis to identify the potential effects of the LkSG on smallholder cocoa farmers. The findings indicate that some, but not all of the risks addressed by the LkSG align with those faced by smallholder cocoa farmers and their families. Additionally, the research also reveals weaknesses, particularly in managing environmental risks, which the LkSG does not adequately cover. Our findings show that in the short- and medium-term, the LkSG has no potential effects on smallholder cocoa farmers. Furthermore, the potential positive impacts of the law on smallholder cocoa farmers will take a long time to realize, as the LkSG considers primarily tier-1 suppliers. Companies in Germany might reassess their supply chains to strive for an LkSG-risk-free supply chain, which could in the long term have sustained impacts on smallholder cocoa farmers. However, we recommend a comprehensive risk analysis of the cocoa supply chain to enhance the human rights of cocoa farmers.}, language = {en} } @inproceedings{KellnerSchroder, author = {Kellner, Florian and Schroder, Nadine}, title = {Location Planning \& Analysis Using Uncertain Data}, series = {2021 International Conference on Decision Aid Sciences and Application (DASA), 07-08 December 2021, Sakheer, Bahrain}, booktitle = {2021 International Conference on Decision Aid Sciences and Application (DASA), 07-08 December 2021, Sakheer, Bahrain}, publisher = {IEEE}, address = {Piscataway, NJ}, isbn = {978-1-6654-1634-4}, doi = {10.1109/DASA53625.2021.9682323}, pages = {720 -- 723}, abstract = {In today's big data era, a humongous amount of data are collected from various sources. In many cases, these data are incomplete, imprecise, and uncertain. An illustrative example is the OpenStreetMap project, where users all over the world contribute data on a more or less precise and complete level. This research shows whether these data are suited to support management decisions. A real-world example demonstrates the extent to which location decisions of a fast-food restaurant chain can be reproduced using techniques from the field of advanced analytics. The problem deals with classifying potential locations and comparing the predicted locations with the actual ones. The data used for this example are retrieved from the OpenStreetMap project. We find that the OpenStreetMap data are generally suitable for predicting location decisions. However, the choice of the data analytics technique is crucial. In our illustrative example case, boosted trees resulted in the best forecast, thereby outperforming neural networks, classic trees, and logit models.}, language = {en} } @article{KraftKellner, author = {Kraft, Sarah Katharina and Kellner, Florian}, title = {Can Blockchain Be a Basis to Ensure Transparency in an Agricultural Supply Chain?}, series = {Sustainability}, volume = {14}, journal = {Sustainability}, number = {13}, publisher = {MDPI}, doi = {10.3390/su14138044}, abstract = {Many supply chains within developing countries lack transparency and are fraught with fraud, corruption, and a substantial number of intermediaries. For several decades, the cocoa sector has faced multiple social, economic, and environmental challenges, some of which include the issue of child labor and very low incomes for farmers, leading to poor living conditions. Blockchain technology has a high potential to reduce—or completely eradicate—some of these hurdles. In this article, we present a blockchain-based solution based on the open-source framework Hyperledger Fabric for the cocoa supply chain to promote transparency and reduce fraud. In doing so, we explicitly describe how farmers can be directly integrated into the whole blockchain solution considering the limited infrastructure, knowledge, and technologies available to them. Since about 70\% of all cocoa worldwide is produced in West Africa, this case study uses the cocoa sector in Ghana as an example.}, language = {en} } @article{KellnerOtto, author = {Kellner, Florian and Otto, Andreas}, title = {Allocating CO2 emissions to shipments in road freight transportation}, series = {Journal of Management Control}, volume = {22}, journal = {Journal of Management Control}, number = {4}, publisher = {Springer}, doi = {10.1007/s00187-011-0143-6}, pages = {451 -- 479}, abstract = {Logistic activity, in particular transportation, produces green house gases (GHG). For different purposes GHG need to be allocated to objects. This paper studies how to allocate the GHG volume of a transportation process (delivery tour) to the single shipments moved by the process. First, it identifies classes of generic allocation schemes and presents 15 allocation methods. Second, since the majority of these methods has not been designed for allocating GHG, we apply and compare them in the short distance transport context within a numerical example. The aim is to study how the schemes perform according to criteria. We suggest using causality, efficiency, empty core robustness, symmetry, individual rationality, coalition stability, ease of application, and set robustness as appraisal criteria and attempt to mainstream the discussion by recommending selected allocation methods.}, language = {en} } @unpublished{KellnerUtz, author = {Kellner, Florian and Utz, Sebastian}, title = {Sustainability in Supplier Selection and Order Allocation: Combining Integer Variables With Markowitz Portfolio Theory}, series = {SSRN Electronic Journal}, journal = {SSRN Electronic Journal}, publisher = {SSRN}, doi = {10.2139/ssrn.3296016}, abstract = {This research presents a decision support methodology for the multi-criteria supplier selection and order allocation problem. The proposed approach supports purchasing managers in assembling mid-term supplier portfolios while making them aware of the trade-offs between the supplier sustainability, the purchasing costs, and the overall supply risk. First, we propose a multi-objective optimization model with three objectives: to maximize the supplier sustainability, to select the supplier portfolio with the lowest purchasing costs, and to minimize the supply risk. Our model extends existing mathematical approaches that follow the portfolio theory fathered by H. Markowitz by integrating the aspect 'risk' into the supplier selection problem. Secondly, since we allow for integer variables in our model — in contrast to the classical Markowitz portfolio theory — we use the ε-constraint method to visualize the efficient surface. The possibility of considering the non-dominated set of supplier portfolios is advantageous for purchasing managers as they gain a picture of the different optimal supplier portfolios and are able to analyze the trade-offs between the different purchasing goals before making a decision. Finally, we illustrate the applicability of the proposed methodology in a real-world supplier selection and order allocation case from the automotive industry. In the example case, we identify 1,754 optimal supplier portfolios that may be assembled based on the eight available suppliers. Our analyses show that each optimal portfolio consists of two suppliers, with one specific supplier being included in each portfolio. Furthermore, four suppliers are not part of any optimal solution.}, language = {en} } @unpublished{Kellner, author = {Kellner, Florian}, title = {Generating Greenhouse Gas Cutting Incentives when Allocating Carbon Dioxide Emissions to Shipments in Road Freight Transportation}, series = {SSRN Electronic Journal}, journal = {SSRN Electronic Journal}, doi = {10.2139/ssrn.3518014}, abstract = {Road freight transportation accounts for a great share of the anthropogenic greenhouse gas (GHG) emissions. In order to provide a common methodology for carbon accounting related to transport activities, the European Committee for Standardization has published the European Norm EN-16258. Unfortunately, EN-16258 contains in its current version some gaps and ambiguities and leaves room for interpretation, which makes the comparison of the environmental performance of different logistics networks still difficult and hinders the identification of best practices. This research aims to overcome the ambiguities of EN-16258 concerning the allocation of GHG emissions to shipments in road freight transportation. In detail, we apply concepts of the cooperative game theory to identify among all allocation units specified by EN-16258 the most meaningful one. In doing so, we continue previous research projects that analyzed two important aspects of the EN-16258 allocation rules: accuracy and fairness. This study provides further insights into this allocation problem by investigating the incentive power of the different allocation schemes to opt for the GHG minimal way of running a road freight transport network. First, we complement the list of transport scenarios introduced by the prior research projects and present two novel transport scenarios. Second, we carry out a series of numerical experiments to compare the performance of the EN-16258 allocation rules with respect to accuracy, fairness, and the GHG minimizing incentive. Across all aspects, and taking the findings of the prior research projects into account, we conclude that the distance-based allocation rule is the most meaningful one.}, language = {en} } @article{KunklerKellner, author = {Kunkler, Jan and Kellner, Florian}, title = {Sustainable City Evaluation Using the Database for Estimation of Road Network Performance}, series = {Sustainability}, volume = {15}, journal = {Sustainability}, number = {1}, publisher = {MDPI}, doi = {10.3390/su15010733}, abstract = {This article introduces the Database for Estimation of Road Network Performance (DERNP) to enable wide-scale estimation of relevant Road Network Performance (RNP) factors for major German cities. The methodology behind DERNP is based on a randomized route sampling procedure that utilizes the Worldwide Harmonized Light Vehicles Test Procedure (WLTP) in combination with the tile-based HERE Maps Traffic API v7 and a digital elevation model provided by the European Union's Earth Observation Programme Copernicus to generate a large set of independent and realistic routes throughout OpenStreetMap road networks. By evaluating these routes using the PHEMLight5 framework, a comprehensive list of RNP parameters is estimated and translated into polynomial regression models for general usage. The applicability of these estimations is demonstrated based on a case study of four major German cities. This case study considers network characteristics in terms of detours, infrastructure, traffic congestion, fuel consumption, and CO2 emissions. Our results show that DERNP and its underlying randomized route sampling methodology overcomes major limitations of previous wide-scale RNP approaches, enabling efficient, easy-to-use, and region-specific RNP comparisons.}, language = {en} } @misc{LauerCorsten, author = {Lauer, Norina and Corsten, Sabine}, title = {Supporting peer-led aphasia support groups with a specific training program: a first proof of concept}, series = {International Aphasia Rehabilitation Conference, London}, journal = {International Aphasia Rehabilitation Conference, London}, language = {en} } @misc{LukeschKellner, author = {Lukesch, Maximilian and Kellner, Florian}, title = {Business Analytics and Big Data: Production, Logistics and Supply Chain Management}, series = {1. Regensburger Big Data Day, 30 Oktober 2018, Regensburg}, journal = {1. Regensburger Big Data Day, 30 Oktober 2018, Regensburg}, doi = {10.5283/epub.37889}, abstract = {Das Poster befasst sich mit dem Beitrag der Auswertung von "Big Data" f{\"u}r die Anwendungsbereiche der Produktion, der Logistik und des Supply Chain Management. Im Kern steht dabei die Anwendung von Business Analytics Methoden und die Umsetzung der Analytics-Ergebnisse in anwendungsorientierte Use Cases. Als Beispiele werden besprochen: Predictive Maintenance, Supply Chain Monitoring, Supply Chain Risk Management, Demand Forecasting.}, language = {en} } @techreport{Krenkel, author = {Krenkel, Lars}, title = {Investigation of the impact of vortex generators on the shock/boundary-layer interaction}, issn = {1434-8454}, abstract = {Comprehensive experimental and numerical parameter studies on the impact of isolated vortex generator pairs and complex vortex generator arrays onto a strong shock-/boundary layer interaction are presented within the context of this thesis. The effects of vortices, especially as they interact with each other are discussed in terms of their impact on the boundary layer development, the shock characteristics and the overall aerodynamic performance of the aerofoil. The presented results have been obtained from wind tunnel experiments with a simple flat plate with superimposed pressure gradient as well as with a more comprehensive model of a supercritical transonic aerofoil. In addition complex numerical parameter studies on a supercritical aerofoil in free stream conditions have been conducted. This work is designed for gaining a better understanding of the fundamental mechanisms of vortex generator/shock/boundary-layer interaction in order to achieve improved flight performance in terms of drag reduction, avoidance or at least postponement of separation onset and shock oscillation as well as lift improvement by application of optimised vortex generator configurations.}, language = {en} } @incollection{ScholzKrenkelTerekhovetal., author = {Scholz, Alexander-Wigbert K. and Krenkel, Lars and Terekhov, Maxim and Friedrich, Janet and Rivoire, Julien and K{\"o}brich, Rainer and Wolf, Ursula and Kalthoff, Daniel and David, Matthias and Wagner, Claus and Schreiber, Laura Maria}, title = {Magnetic Resonance Imaging and Computational Fluid Dynamics of High Frequency Oscillatory Ventilation (HFOV)}, series = {Fundamental Medical and Engineering Investigations on Protective Artificial Respiration}, volume = {116}, booktitle = {Fundamental Medical and Engineering Investigations on Protective Artificial Respiration}, editor = {Hirschel, Ernst Heinrich and Schr{\"o}der, Wolfgang and Fujii, Kozo and Haase, Werner and Leer, Bram and Leschziner, Michael A. and Pandolfi, Maurizio and Periaux, Jacques and Rizzi, Arthur and Roux, Bernard and Shokin, Yurii I. and Klaas, Michael and Koch, Edmund and Schr{\"o}der, Wolfgang}, publisher = {Springer}, address = {Berlin, Heidelberg}, isbn = {978-3-642-20325-1}, doi = {10.1007/978-3-642-20326-8_7}, pages = {107 -- 128}, abstract = {In order to better understand the mechanisms of gas transport during High Frequency Oscillatory Ventilation (HFOV) Magnetic Resonance Imaging (MRI) with contrast gases and numerical flow simulations based on Computational Fluid Dynamics(CFD) methods are performed. Validation of these new techniques is conducted by comparing the results obtained with simplified models of the trachea and a first lung bifurcation as well as in a cast model of the upper central airways with results achieved from conventional fluid mechanical measurement techniques like e.g. Laser Doppler Anemometry (LDA). Further it is demonstrated that MRI of experimental HFOV is feasible and that Hyperpolarized 3He allows for imaging the gas re-distribution inside the lung. Finally, numerical results of oscillatory flow in a 3rd generation model of the lung as well as the impact of endotracheal tubes on the flow regime development in a trachea model are presented.}, language = {en} } @incollection{RuettenKrenkel, author = {R{\"u}tten, Markus and Krenkel, Lars}, title = {Vortex-Generator Pairs for Vortex-Induced Heat-Transfer Enhancement in Heat-Exchanger Channels}, series = {New Results in Numerical and Experimental Fluid Mechanics VII : Contributions to the 16th STAB/DGLR Symposium Aachen, Germany 2008}, booktitle = {New Results in Numerical and Experimental Fluid Mechanics VII : Contributions to the 16th STAB/DGLR Symposium Aachen, Germany 2008}, editor = {Hirschel, Ernst Heinrich and Schr{\"o}der, Wolfgang and Fujii, Kozo and Haase, Werner and Leer, Bram and Leschziner, Michael A. and Pandolfi, Maurizio and Periaux, Jacques and Rizzi, Arthur and Roux, Bernard and Shokin, Yurii I. and Dillmann, Andreas and Heller, Gerd and Klaas, Michael and Kreplin, Hans-Peter and Nitsche, Wolfgang}, publisher = {Springer Berlin Heidelberg}, address = {Berlin, Heidelberg}, isbn = {978-3-642-14242-0}, doi = {10.1007/978-3-642-14243-7_68}, pages = {555 -- 562}, abstract = {The objective of the presented work is to investigate possibilities for increasing the heattransfer in heat-exchanger channels for aircraft applications by using flow-manipulating devices. Focal point of the investigation are different arrangements of vortex-generator pairs within a generic heat-exchanger channel. The DLR URANS CFD solver THETA has been used to carry out numerical simulations of the laminar flow within a rectangular channel with integrated vortex generators. In particular, the analysis of the interaction of generated vortices with the stratified thermal boundary layer, the impact of vortical flow structures on heated walls and the enforced mixed-convection flow is of special interest. The final goal is the evaluation of the applicability of oppositely arranged vortex-generator pairs for the enhancement of vortex-induced heat-transfer.}, language = {en} } @inproceedings{KrenkelPennecotLenzetal., author = {Krenkel, Lars and Pennecot, Julien and Lenz, Christian and Feldmann, Daniel and Wagner, Claus}, title = {Optimierung der Hochfrequenz-Oszillationsventilation mittels str{\"o}mungsmechanischer Methoden und kontrastgasgest{\"u}tzter Magnetresonanztomografie - Teilprojekt: Rekonstruktion von Geometrien aus medizinischen Bilddaten und Erstellung von Modellen f{\"u}r experimentelle Str{\"o}mungsuntersuchungen}, series = {Laseranwendung in der Medizin, Erfassen und Verarbeiten kardiovaskul{\"a}rer Signale, protektive Beatmungskonzepte : 3. Dresdner Medizintechnik-Symposium - mit DFG-Forschungsschwerpunkt Protektive Beatmungskonzepte, 6. bis 9. Dezember 2010, Dresden}, booktitle = {Laseranwendung in der Medizin, Erfassen und Verarbeiten kardiovaskul{\"a}rer Signale, protektive Beatmungskonzepte : 3. Dresdner Medizintechnik-Symposium - mit DFG-Forschungsschwerpunkt Protektive Beatmungskonzepte, 6. bis 9. Dezember 2010, Dresden}, editor = {F{\"u}ssel, Jens and Koch, Edmund and Malberg, Hagen}, publisher = {TUDpress}, address = {Dresden}, isbn = {978-3-942710-02-2}, pages = {107 -- 114}, abstract = {Der vorliegende Artikel skizziert die neu entwickelte Prozesskette f{\"u}r detailgenaue Rekonstruktion von Geometrien anhand medizinischer Bilddaten sowie die Herstellung von transparenten Modellen f{\"u}r experimentelle Untersuchungen mit bildgebenden Str{\"o}mungsmessverfahren. Die Geometriedaten und Modelle werden f{\"u}r systematische Untersuchungen der komplexen Transportvorg{\"a}nge in den Atemwegen bei k{\"u}nstlicher Beatmung mittels Hochfrequenzoszillationsventilation (HFOV) verwendet.}, language = {en} } @article{HornRaptisFischeretal., author = {Horn, Lars-Christian and Raptis, Georgios and Fischer, Uta and Hentschel, Bettina and K{\"o}hler, U. and Richter, Christine E. and Martin, Rosemarie}, title = {CD44-v6 concentrations in carcinoma of the uterine cervix: lack of prognostic significance}, series = {Archives of Gynecology and Obstetrics}, volume = {273}, journal = {Archives of Gynecology and Obstetrics}, number = {2}, doi = {10.1007/s00404-005-0039-5}, pages = {104 -- 106}, abstract = {Several kinds of cellular adhesion molecules, like different splicing variants of CD 44, have gained important as prognostic or markers for metastatic disease. Fresh frozen samples from 64 cervical carcinoma (CX) were stored in liquid nitrogen and examined using ELISA-technique, testing the prognostic impact. Normal cervical tissue served as control. CD 44-v6 concentration, was significant elevated in tumor tissue, when compared to the controls (P=0.04). There was no correlation to tumor stage (P=0.61), lymphovascular space involvement (P=0.075) or pelvic lymph node involvement (P=0.81). The CD 44-v6 concentration was not informative regarding recurrence-free and overall survival. Contrary to immunohistochemistry, the quantification of CD 44-v6 using ELISA-technique does not provide any further information.}, subject = {Geb{\"a}rmutterhalskrebs}, language = {en} } @inproceedings{WiesmaierLippertKaratsiolisetal., author = {Wiesmaier, Alexander and Lippert, Markus and Karatsiolis, Vangelis and Raptis, Georgios and Buchmann, Johannes}, title = {An Evaluated Certification Services System for the German National Root CA - Legally Binding and Trustworthy Transactions in E-Business and E-Government}, series = {Proceedings of The 2005 International Conference on E-Business, Enterprise Information Systems, E-Government, and Outsourcing, EEE 2005, Las Vegas, Nevada, USA, June 20-23, 2005}, booktitle = {Proceedings of The 2005 International Conference on E-Business, Enterprise Information Systems, E-Government, and Outsourcing, EEE 2005, Las Vegas, Nevada, USA, June 20-23, 2005}, publisher = {CSREA Press}, isbn = {1-932415-76-9}, pages = {103 -- 108}, language = {en} } @article{HornFischerRaptisetal., author = {Horn, Lars-Christian and Fischer, Uta and Raptis, Georgios and Bilek, Karin and Hentschel, Bettina and Richter, Christine E. and Braumann, Ulf Dietrich and Einenkel, Jens}, title = {Pattern of invasion is of prognostic value in surgically treated cervical cancer patients}, series = {Gynecologic Oncology}, volume = {103}, journal = {Gynecologic Oncology}, number = {3}, doi = {10.1016/j.ygyno.2006.05.046}, pages = {906 -- 911}, abstract = {Objectives: Different patterns of invasion (representing different grades of tumor cell dissociation) are associated with prognostic outcome in cancer. We evaluated the prognostic value of different patterns of invasion (PI) in cervical carcinomas (CX). Methods: Six hundred eleven surgically treated CX (FIGO IB to IIB) were re-evaluated histologically regarding the PI, using a three-level scoring system. Closed PI was defined as cohesive growth with well-delineated (pushing) borders. In finger-like PI the tumor grows in solid cords/trabecles. Highly dissociative growth in small groups or single cells was defined as spray-like PI. Types of PI were correlated to tumor stage, histo-morphologic factors and prognostic outcome. Results: Sixty percent of the tumors showed a spray-like PI, 30\% a finger-like PI and only 7.4\% were of the closed type. Spray-like PI showed a significant correlation with advanced stage disease, lymphovascular space involvement, poorly differentiated tumors and pelvic lymph node metastases. Spray-like PI was accompanied by a reduced 5-year overall survival when compared to the finger-like and closed PI (68.7\% vs. 80.9\% vs. 88.5\%; P=0.0004). The prognostic impact of the PI disappeared in node-positive patients (P=0.06) but persisted in patients without pelvic lymph node disease (P=0.03). In multivariate analysis, using COX regression model, the PI represented as independent prognostic factor. Conclusions: Spray-like PI (i.e., highest degree of tumor cell dissociation) is associated with advanced tumor stages, increased rate of recurrency and a reduced overall survival. In separate analysis of patients with and without lymph node metastases, the impact of PI persisted only in node-negative cases as a prognostic factor.}, subject = {Geb{\"a}rmutterhalskrebs}, language = {en} } @article{HornFischerRaptisetal., author = {Horn, Lars-Christian and Fischer, Uta and Raptis, Georgios and Bilek, Karin and Hentschel, Bettina}, title = {Tumor size is of prognostic value in surgically treated FIGO stage II cervical cancer}, series = {Gynecologic Oncology}, volume = {107}, journal = {Gynecologic Oncology}, number = {2}, doi = {10.1016/j.ygyno.2007.06.026}, pages = {310 -- 315}, abstract = {Objectives Tumor size is a well recognized prognostic factor in early stage cervical carcinoma (CX). However, limited knowledge exists about the value of tumor size in surgically treated CX with extrauterine extension. Methods 245 cases of local advanced CX (FIGO stage IIA and IIB) who received upfront surgery were evaluated regarding tumor size, regarding the prediction of pelvic lymph node involvement and recurrence free and overall survival during a median follow-up time of 54 months (95\% CI 45.4-62.6 months). Tumors larger than 4 cm were defined as bulky stage disease. Results Bulky disease was seen in 46.1\% (113/245). 60.2\% of these patients showed pelvic lymph node involvement, compared to 42.4\% (56/132) in non-bulky tumors (p = 0.006; odds ratio: 2.2 [95\% CI: 1.3-3.6]). Patients with bulky tumors showed an increase of recurrent disease (40.2\% vs. 28.0\%; p = 0.045). The relative risk for recurrent disease was 1.97 (95\% CI: 1.3-3.0). The 5-year overall survival rate was significantly lower (67.7\% [95\% CI: 58.2-74.8] vs. 49.5\% [95\% CI: 36.8-59.1]; p = 0.0015). In multivariate analysis, tumor stage, pelvic lymph node involvement and maximal tumor size were independent prognostic factors. Conclusions The results suggest that tumor size, defining bulky disease as tumors larger than 4 cm, is of prognostic impact also in FIGO stage II cervical carcinomas. A revised FIGO/TNM classification system similar to the subgrouping of stage IB CX is recommended for stage II using a cut-off value of 4 cm as discriminator: stage IIA1 and stage IIB1 for tumors with ≤ 4 cm and IIA2 and IIB2 for tumors > 4 cm (i.e. bulky disease).}, subject = {Geb{\"a}rmutterhalskrebs}, language = {en} } @inproceedings{HoehRaptis, author = {H{\"o}h, H. and Raptis, Georgios}, title = {Applications of the Erbium: YAG Laser in Ophthalmology - Cataracta-, Glaukoma-, Eyelid-Surgery and pars plana Vitrectomy}, abstract = {Recent developments in lasers have provided us the possibility of laser ocular surgery. The xenon, argon, neodymium:YAG and dye lasers have been successfully used in out-patient clinics. The excimer laser has been attracting researchers' interest in the new application of laser to cornea and lens. The erbium:YAG laser emits a 2.94-microns beam that can ablate the transparent ocular tissues such as lenses and corneas. The author has applied this laser to the cornea, lens, vitreous and other ocular tissues. The erbium:YAG laser beam was directed through a 1.5-meter-long, 200-microns-diameter fiberoptic guide. The radiant energy measured about 50 mJ at the end of the probe. The laser was emitted as a 400-microsecond pulse. Freshly enucleated rabbit eyes were used in this study. Laser burns were applied to the tissue surface at various energy settings. At minimal power, the tissues were coagulated by the erbium:YAG laser application. At a power of more than 636-954 mJ/mm2, tissue began to evaporate; the tissue loss was observed under a surgical light microscope. Corneal photoablation, lens ablation, iridotomy, trabeculotomy, cutting of the vitreous and retinal ablation were easily performed. Like the excimer laser, the erbium:YAG laser is a potential tool for ocular surgery.}, subject = {Augenchirurgie}, language = {en} } @article{ReichHornberger, author = {Reich, Sven and Hornberger, Helga}, title = {The effect of multicolored machinable ceramics on the esthetics of all-ceramic crowns}, series = {Journal of Prosthetic Dentistry}, volume = {88}, journal = {Journal of Prosthetic Dentistry}, number = {1}, pages = {44 -- 49}, abstract = {Statement of problems: Computer-aided design/computer-assisted machining systems offer the possibility of fabricating restorations from one machinable ceramic block. Whether multishaded blocks improve esthetic results and are a viable alternative to individually stained ceramics has not been fully determined. Purpose: The aim of this investigation was to examine the effect of multishaded blocks on the esthetic appearance of all-ceramic CEREC crowns and compare these crowns with single-shade and stained restorations. Material and methods: Ten subjects were included in this study. For each subject, 6 different crowns were milled with the use of a CEREC machine. One crown was milled from each of the following machinable ceramic materials: CEREC Vitablocs Mark II in classic colors; Vitablocs Mark II in 3D-Master colors; Vitablocs Mark II in either classic or 3D-Master colors, with additional staining; Megadenta Bloxx multishaded; Mark II experimental multilayer; and an experimental multilayer leucite ceramic. Three independent examiners assessed the esthetic appearance of crowns fabricated to match each subject's anterior tooth shade. A scale of 1 to 6 was used to score the shade match and esthetic adaptation of each crown, with 1 representing excellent characteristics and 3.5 serving as the threshold for clinical acceptability. The examiners' scores were averaged, and the mean values were analyzed with the Wilcoxon signed rank test (P or = 1.70, with a (70:30) 2.3-fold risk of recurrence (P=.024) and reduced RFS of 10 months (P=.003) in cases of DI > or = 1.70. A high 5c-ER > 11\% was associated with pelvic lymph node involvement and decreased RFS (P < or = .04). Significantly more relapses were found in tumors with SPF > 12\% (70.8\% vs. 29.2\%, P=.007). RFS was markedly reduced in tumors with high SPF (52.3 vs. 61.1 months, P=.011). Low proliferative tumors (PI<25\%) were associated with lower stage (P=.036) and increased RFS (61.2 vs. 47.1 months, P=.028). In multivariate analysis of clinicopathologic variables (pT category, nodal status, lymphovascular space involvement) and DNA related variables, pelvic lymph node involvement was the only significant predictor of RFS. In patients with nodal involvement, tumors with DI >1.70 were associated with lessfavorable outcomes. Conclusion: DNA-related variables of cell cycle analysis were valuablefor predicting prognosis in cervical cancer patients. Tumors with DI>1.70, 5c-ER >11\% and high proliferative activity (SPF>12\%, PI>25\%) represent a subgroup with a poor prognosis.}, subject = {Geb{\"a}rmutterhals}, language = {en} } @article{HornPippigRaptisetal., author = {Horn, Lars-Christian and Pippig, S. and Raptis, Georgios and Fischer, Uta and K{\"o}hler, U. and Hentschel, Bettina and Martin, Rosemarie}, title = {Clinical relevance of urokinase-type plasminogen activator and its inhibitor type-1 (PAI-1) in squamous cell carcinoma of the uterine cervix}, series = {Australian and New Zealand Journal of Obstetrics and Gynaecology}, volume = {42}, journal = {Australian and New Zealand Journal of Obstetrics and Gynaecology}, number = {4}, doi = {10.1111/j.0004-8666.2002.00385.x}, pages = {385 -- 388}, abstract = {Objective The expression of uPA and PAI-1 as parameters of tumour-associated proteolysis has been implicated in the process of tumour cell invasion and the metastatic process. However, there is limited information on the impact of these parameters in cervical carcinoma. Methods Quantitative levels for uPA (n = 114) and PAI-1 (n = 103) were researched in operatively treated, surgically staged squamous cell cancer of the uterine cervix, using an ELISA-technique. Results were assessed regarding their impact in predicting pelvic lymph nodes metastases, tumour recurrence rate and recurrence free survival (RFS) using uni- and multivariate analysis. Results Median levels of both parameters were significantly higher in tumour tissue than in normal cervical tissue (p < 0.001). Detection of uPA gave no useful prognostic information. PAI-1 concentration showed a positive correlation with advanced tumour stage (p = 0.008), but no significant correlation with nodal status (pN0: 2.6 vs. pN1: 4.0 ng/mg protein; p = 0.092). Using a cut-off level of 2.4 ng/mg protein, patients with elevated PAI-1 levels demonstrated reduced RFS (45.9 versus 52.9 months; p = 0.1). Multivariate analysis, including nodal status, tumour stage, lymphovascular space involvement and grading failed to demonstrate any prognostic impact of uPA and PAI-1. Conclusions The results indicate, that PAI-1 expression is of some prognostic impact in cervical cancer, indicating an association of elevated PAI levels with local tumour progression and reduced recurrence-free survival.}, subject = {Plasminogen human-Aktivator}, language = {en} }