@article{DubberkeLinnemannAbbasetal.2018, author = {Dubberke, Frithjof H. and Linnemann, Matthias and Abbas, Wameedh Khider and Baumh{\"o}gger, Elmar and Priebe, Klaus-Peter and Roedder, Maximilian and Neef, Matthias and Vrabec, Jadran}, title = {Experimental setup of a cascaded two-stage organic Rankine cycle}, series = {Applied Thermal Engineering}, volume = {131}, journal = {Applied Thermal Engineering}, publisher = {Elsevier}, doi = {10.1016/j.applthermaleng.2017.11.137}, pages = {958 -- 964}, year = {2018}, abstract = {In combination with a bottoming cycle, operated with a pure fluid in transcritical mode, the usage of a zeotropic mixture as a working fluid appears to be exergetically favorable for power cycle efficiency in cascaded two-stage organic Rankine cycles (CORC). A CORC is set up and initially tested with cyclopentane and propane as working fluids in its high temperature and low temperature cycle, respectively. A thermal oil cycle serves as the heat source and is powered electrically with a maximum heat flow of 158 kW. The design of this experimental setup allows for a rapid replacement of individual components and for a wide range of conditions in terms of fluids and thermodynamic states. The components of all cycles and the measurement and control technology are described in detail. A testing procedure is presented, followed by a discussion of the measurement results, where it is shown that the intended concept of two cascaded organic Rankine cycles is operational and that the measured data are consistent.}, language = {en} } @article{LauxGotterEckertetal.2022, author = {Laux, Christoph and Gotter, Andreas and Eckert, Frank and Neef, Matthias}, title = {Experimental results of a low-pressure steam Rankine cycle with a novel water lubricated radial inflow turbine for the waste heat utilization of internal combustion engines}, series = {Energy Conversion and Management}, volume = {271}, journal = {Energy Conversion and Management}, publisher = {Elsevier}, issn = {0196-8904}, doi = {10.1016/j.enconman.2022.116265}, year = {2022}, language = {en} } @inproceedings{BatosJahrCorves2015, author = {Batos, Andrej and Jahr, Andreas and Corves, B.}, title = {Experimental Investigations for the Characterization of Cutting Processes on Biomaterials [Oralposter]}, series = {European Symposium and Exhibition on Biomaterials and Related Areas - Euro BioMAT 2015}, booktitle = {European Symposium and Exhibition on Biomaterials and Related Areas - Euro BioMAT 2015}, year = {2015}, language = {en} } @article{BhattacharyyaBenimChattopadhyayetal.2019, author = {Bhattacharyya, Suvanjan and Benim, Ali Cemal and Chattopadhyay, Himadri and Banerjee, Arnab}, title = {Experimental investigation of heat transfer performance of corrugated tube with spring tape inserts}, series = {Experimental Heat Transfer}, volume = {32}, journal = {Experimental Heat Transfer}, number = {5}, publisher = {Taylor \& Francis}, issn = {0891-6152}, doi = {10.1080/08916152.2018.1531955}, pages = {411 -- 425}, year = {2019}, language = {en} } @inproceedings{LauxGotterNeef2019, author = {Laux, Christoph and Gotter, Andreas and Neef, Matthias}, title = {Experimental investigation of a low pressure steam Rankine cycle for waste heat utilization of internal combustion engines}, series = {Proceedings of the 5th International Seminar on ORC Power Systems}, booktitle = {Proceedings of the 5th International Seminar on ORC Power Systems}, publisher = {The National Technical University of Athens (NTUA)}, address = {Athens}, isbn = {978-90-9032038-0}, year = {2019}, abstract = {High heat losses via exhaust gas and coolant in internal combustion engines (ICE) are the basis for numerous investigations regarding downstream processes for power generation. The most promising concepts are Organic Rankine Cycles (ORC) and Steam Rankine Cycles (SRC). In previous work of the Center of Innovative Energy Systems, D{\"u}sseldorf (Germany), the technical and economic feasibility of a low pressure SRC has been investigated and the advantages in comparison to organic Rankine cycles are highlighted. A distinctive feature of the cycle is the use of the ICE coolant heat for evaporation, which limits the cycles maximum steam pressure to values below atmospheric pressure. This work presents first results of a test rig with data reconciliation according to DIN 2048 to validate the simulation results and design calculations. As a basis for the experimental investigations, a gas fired CHP plant was selected. The design of the test rig is optimized for the operation in the laboratory, where the coolant heat is emulated by a tempering device and the exhaust heat of the CHP plant is emulated by a gas burner. With the designed test rig, it is possible to control the volume flow and the temperatures of the coolant and exhaust gas, so that different load conditions of the gas fired CHP plant can be investigated. For initial tests, the turbine in the SRC is replaced by a throttle to achieve the pressure drop of the turbine. The experimental results show, that the exhaust and coolant heat of a 36 kWel CHP plant can be emulated and the performance expectations of the cycle can be met in stable steady-state conditions. Based on the measurement results and the turbine design calculations an electric power output of the cycle of 3.8 kW will be possible, which results in a cycle efficiency of about 6.5 \% and an increase of the electrical power output of the CHP plant of about 10 \%. The results show that the plant concept is technically feasible and, with further optimization, also represents an alternative to ORC plants in terms of increasing the efficiency of a cogeneration plant.}, language = {en} } @article{FuchsHofzumahausRohreretal.2013, author = {Fuchs, H. and Hofzumahaus, A. and Rohrer, F. and Bohn, Birger and Brauers, Theo and Dorn, Hans-Peter and H{\"a}seler, R. and Holland, F. and Kaminski, M. and Li, X. and Lu, K. and Nehr, Sascha and Tillmann, R. and Wegener, R. and Wahner, A.}, title = {Experimental evidence for efficient hydroxyl radical regeneration in isoprene oxidation}, series = {Nature Geoscience}, volume = {6}, journal = {Nature Geoscience}, number = {12}, publisher = {Springer Nature}, issn = {1752-0894}, doi = {10.1038/NGEO1964}, pages = {1023 -- 1026}, year = {2013}, language = {en} } @article{SulaimanSaberHasanetal.2025, author = {Sulaiman, Mohammed A. and Saber, Hindren Ali and Hasan, Hasan F. and Benim, Ali Cemal}, title = {Experimental and numerical investigation of novel dew-point evaporative cooler with shell and tube design}, series = {Energy}, volume = {317}, journal = {Energy}, publisher = {Elsevier}, issn = {0360-5442}, doi = {10.1016/j.energy.2025.134686}, year = {2025}, subject = {Numerische Str{\"o}mungssimulation}, language = {en} } @unpublished{SulaimanSaberHasanetal.2024, author = {Sulaiman, Mohammed Abdulqader and Saber, Hindren Ali and Hasan, Hasan Fahmi and Benim, Ali Cemal}, title = {Experimental and Numerical Investigation of Novel Dew-Point Evaporative Cooler with Shell and Tube Design}, series = {SSRN}, journal = {SSRN}, publisher = {Elsevier}, doi = {10.2139/ssrn.4980477}, pages = {38}, year = {2024}, abstract = {Implementing a neoteric practical design for dew-point evaporative cooler (DPEC) rather than the widely utilized flat plate and corrugated plate has been challenging since the first invention. Thus far, no study has been dedicated to design and experimentally implement a shell and tube concept for DPEC with an innovative configuration that can contribute in mass production, globalization, and effortless maintenance of such a high performance cooling machine. Therefore, in this paper, the shell and tube concept has been employed as a core design for DPEC that has been reinforced by a practical approaches. The practical approaches include a dedicated novel design for the proposed system and utilizing super cheap materials for the system's construction. Both of the aforementioned approaches provide solutions for overcoming the aforementioned issues. In the meanwhile, the superiority of the proposed DPEC has been approved by comparing it to the flat plate DPEC. During the experimentations, the prototype was able to reduce the ambient temperature by up to 34.1°C (from 53°C to 18.9°C), besides, it could achieve a dew-point effectiveness of 99.6\% and wet-bulb effectiveness of 135\%.}, subject = {Numerische Str{\"o}mungssimulation}, language = {en} } @article{BenimEscudierNahavandietal.2010, author = {Benim, Ali Cemal and Escudier, Marcel and Nahavandi, Ali and Nickson, A. K. and Syed, Khawar J. and Joos, Franz}, title = {Experimental and numerical investigation of isothermal flow in an idealized swirl combustor}, series = {International Journal of Numerical Methods for Heat \& Fluid Flow}, volume = {20}, journal = {International Journal of Numerical Methods for Heat \& Fluid Flow}, number = {3}, publisher = {Emerald}, doi = {10.1108/09615531011024084}, pages = {348 -- 370}, year = {2010}, language = {en} } @article{IqbalBenimFischeretal.2016, author = {Iqbal, Sohail and Benim, Ali Cemal and Fischer, S. and Joos, F. and Kluβ, D. and Wiedermann, Alexander}, title = {Experimental and numerical analysis of natural bio and syngas swirl flames in a model gas turbine combustor}, series = {Journal of Thermal Science}, volume = {25}, journal = {Journal of Thermal Science}, number = {5}, publisher = {Springer}, doi = {10.1007/s11630-016-0885-4}, pages = {460 -- 469}, year = {2016}, language = {en} } @article{MinartzVondebergObertetal.2025, author = {Minartz, Peter and Vondeberg, Carmen and Obert, Laura and Bleck, Christian and Hemming, Bernhard and V{\"o}cking, Mara and Ose, Claudia and Znotka, Matti and C{\"u}rlis, Diana and Karrenbrock, Anne and Oehmichen, Frank and Heistermann, Peter and Kuske, Silke}, title = {Experiencing digital technologies: The importance of feeling safe in healthcare - A qualitative participatory design}, series = {Das Gesundheitswesen}, journal = {Das Gesundheitswesen}, publisher = {Thieme}, issn = {0941-3790}, doi = {10.1055/a-2560-1100}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:due62-opus-52945}, pages = {13}, year = {2025}, abstract = {Background Digital technologies are increasingly used in healthcare. In this context, perceived safety plays a critical role in their acceptance and implementation. Previous research had focused more on data security or specific digital technologies. There has also been a lack of participatory approaches to consider and empower healthcare recipients (and relatives), providers, and technology experts to broaden the phenomenon. Objective The aim of this study was to present a comprehensive perspective on the needs, influencing factors and related outcomes in the context of feeling safe with digital technologies in healthcare. Method A qualitative, exploratory, and participatory methodology was used with five guide-based focus group workshops. Each workshop explored one of five digital technology demonstrations provided at the beginning: (1) electronic health records (EHR), (2) robotics, (3) artificial intelligence (AI), (4) smart home, and (5) smart hospital. All participants were invited for a guide-based discussion. The study focused on the levels of 'involvement' and 'collaboration' by also empowering participation. The workshop target groups were actively involved in the development and execution of the workshops and were empowered. The data were analysed via a content analysis approach, with a mostly inductive procedure. Results Feeling safe was found to affect thoughts, emotions, and actions. For example, a higher level of perceived safety increased the acceptance of digital technologies, whereas a lower level of perceived safety decreased it. The corresponding needs and influencing factors differed in terms of their scope and focus depending on the context. The aspect of 'control' was most frequently addressed by all the target groups and was viewed as relevant in all the workshops. In general, digital technologies were viewed as supplements rather than substitutes for healthcare providers. Conclusion This study extends beyond the current state of research on perceived safety and the use of digital technologies in healthcare by providing a comprehensive overview of the corresponding needs and influencing factors at various levels, such as the individual, community-organizational, and system-society levels. The perceived safety of healthcare recipients and providers related to digital technologies should be taken into consideration to achieve positive implementation outcomes.}, subject = {Digitalisierung}, language = {en} } @article{MuellerBraunKeuper2025, author = {M{\"u}ller, Patrick and Braun, Alexander and Keuper, Margret}, title = {Examining the Impact of Optical Aberrations to Image Classification and Object Detection Models}, series = {IEEE Transactions on Pattern Analysis and Machine Intelligence}, journal = {IEEE Transactions on Pattern Analysis and Machine Intelligence}, publisher = {IEEE}, issn = {0162-8828}, doi = {10.1109/TPAMI.2025.3622234}, pages = {1 -- 15}, year = {2025}, language = {en} } @inproceedings{WeberThielkeFischer2019, author = {Weber, Konradin and Thielke, Jan and Fischer, Christian}, title = {Evaluation of selected physical parameters measured with smartphones}, series = {Verhandlungen der Deutschen Physikalische Gesellschaft e.V.}, booktitle = {Verhandlungen der Deutschen Physikalische Gesellschaft e.V.}, publisher = {Deutsche Physikalische Gesellschaft e.V.}, address = {Bad Honnef}, year = {2019}, subject = {Messtechnik}, language = {en} } @article{NovelliKaminskiRolletteretal.2018, author = {Novelli, Anna and Kaminski, Martin and Rolletter, Michael and Acir, Ismail-Hakki and Bohn, Birger and Dorn, Hans-Peter and Li, Xin and Lutz, Anna and Nehr, Sascha and Rohrer, Franz and Tillmann, Ralf and Wegener, Robert and Holland, Frank and Hofzumahaus, Andreas and Kiendler-Scharr, Astrid and Wahner, Andreas and Fuchs, Hendrik}, title = {Evaluation of OH and HO2 concentrations and their budgets during photooxidation of 2-methyl-3-butene-2-ol (MBO) in the atmospheric simulation chamber SAPHIR}, series = {Atmospheric Chemistry and Physics}, volume = {18}, journal = {Atmospheric Chemistry and Physics}, number = {15}, publisher = {Copernicus}, issn = {1680-7324}, doi = {10.5194/acp-18-11409-2018}, pages = {11409 -- 11422}, year = {2018}, abstract = {Several previous field studies have reported unexpectedly large concentrations of hydroxyl and hydroperoxyl radicals (OH and HO2, respectively) in forested environments that could not be explained by the traditional oxidation mechanisms that largely underestimated the observations. These environments were characterized by large concentrations of biogenic volatile organic compounds (BVOC) and low nitrogen oxide concentration. In isoprene-dominated environments, models developed to simulate atmospheric photochemistry generally underestimated the observed OH radical concentrations. In contrast, HO2 radical concentration showed large discrepancies with model simulations mainly in non-isoprene-dominated forested environments. An abundant BVOC emitted by lodgepole and ponderosa pines is 2-methyl-3-butene-2-ol (MBO), observed in large concentrations for studies where the HO2 concentration was poorly described by model simulations. In this work, the photooxidation of MBO by OH was investigated for NO concentrations lower than 200 pptv in the atmospheric simulation chamber SAPHIR at Forschungszentrum J{\"u}lich. Measurements of OH and HO2 radicals, OH reactivity (kOH), MBO, OH precursors, and organic products (acetone and formaldehyde) were used to test our current understanding of the OH-oxidation mechanisms for MBO by comparing measurements with model calculations. All the measured trace gases agreed well with the model results (within 15 \%) indicating a well understood mechanism for the MBO oxidation by OH. Therefore, the oxidation of MBO cannot contribute to reconciling the unexplained high OH and HO2 radical concentrations found in previous field studies.}, language = {en} } @article{NeefFritzenSchumacher2003, author = {Neef, Matthias and Fritzen, J. P. and Schumacher, G.}, title = {Evaluation of mount loads in dynamic testing of a jet engine}, series = {Mechanical Systems and Signal Processing}, volume = {17}, journal = {Mechanical Systems and Signal Processing}, number = {3}, publisher = {Elsevier}, doi = {10.1006/mssp.2001.1405}, pages = {665 -- 681}, year = {2003}, abstract = {In the dynamic testing of jet engines the evaluation of loads on the mount structure is vital for comparison with finite element calculations of such testing. Measuring these loads with the help of strain gauges applied to the structure becomes difficult if the mount is overdetermined and thus not every strain gauge can be assigned to a single load direction. In this study, the overdetermined mount structure of the BR715 engine was examined at one of the three mounting points between the Boeing 717 airframe and the engine, where loads in five directions were reacted. Firstly, the dependence of five measured strains upon known static load conditions at the mounting point had to be determined. For this purpose a static calibration test was carried out where defined forces and moments in known directions were applied to the structure while the output from five strain gauges was measured accordingly. The result was the desired relationship between loads and strains in terms of a matrix, which yields the corresponding load condition of the examined mounting point if multiplied with a set of strains. The same calibration procedure was carried out with a finite element model of the mount, where direct comparison to dynamic load results from the model itself was possible. With this model the validity of the above method was shown as well as possible errors which may occur while evaluating dynamic test results. The method was found to give satisfactory results even for dynamic loading, although some inertia forces disturb the signals in dynamic testing. Finally, the results from an actual dynamic engine test were processed into loads and then compared to the simulated loads from a finite element model of the engine. Good agreement was found and the indication of any remaining discrepancies was used to update the model for an even better representation of the dynamic test loads.}, language = {en} } @inproceedings{WeberKramerFischeretal.2019, author = {Weber, Konradin and Kramer, Tim and Fischer, Christian and Pohl, Tobias and B{\"o}hlke, Christoph}, title = {Evaluation of low cost and mid cost sensors for fine particulate matter at urban sites}, series = {Geophysical Research Abstracts: EGU General Assembly 2019}, volume = {21}, booktitle = {Geophysical Research Abstracts: EGU General Assembly 2019}, publisher = {Copernicus}, address = {G{\"o}ttingen}, year = {2019}, abstract = {High ambient air concentrations of fine particulate matter are a problem in many European cities, especially in traffic loaded street canyons. Therefore, the introduction of traffic restricted or traffic reduced areas is discussed as a countermeasure in several towns. However, at that point it is not always clear, in what extent the restriction of traffic in presently overloaded streets causes the exceeding of limit values in other areas of the town after the redirection of the traffic. Presently this cannot be recorded appropriately, when the concentrations of fine particulate matter are monitored only at rarely distributed single points by the official measurement systems of the environmental state agencies. On the other hand, meanwhile there are low cost and mid cost sensors for the measurement of fine particulate matter available, which enable the parallel monitoring with many measurement systems in an extended area of the town. By this way, the effect of traffic restrictions on the distribution of fine particulate matter in the city can potentially be observed. However, at this point the question arises, how reliable the results are, which are delivered by the low and mid cost sensors for fine particulate matter. For this reason different low cost and mid cost sensors have been evaluated for this study and intercompared with certified reference measurement systems for fine particulate matter. The study comprised the sensors SDS011 (Nova Fitness), which is in use already for several citizen science projects in Germany, SPS30 (Sensirion), OPC-R1 (Alphasense), OPC-N2 (Alphasense) and OPC-N3 (Alphasense). This study was performed at urban sites in D{\"u}sseldorf (Germany) for several weeks and covered different traffic loads and different meteorological situations, in order to get representative results. As atmospheric humidity can influence the measurement results, the humidity was measured in parallel to the fine particulate matter. It could be shown that the validity of the measurement results of fine particulate matter could be improved, when the parallel readings of the humidity were taken into account.}, subject = {Messtechnik}, language = {en} } @inproceedings{KerstenHaaseRiess2025, author = {Kersten, Thierry and Haase, Thomas and Riess, Bernhard M.}, title = {Evaluation of a new AI driven SoC Design Flow Approach}, series = {MPC-Workshop Januar 2024 / Januar 2025}, volume = {67/68}, booktitle = {MPC-Workshop Januar 2024 / Januar 2025}, editor = {Schmidt, Lothar}, publisher = {Technische Hochschule Ulm}, address = {Ulm}, organization = {Multi Projekt Chip Gruppe}, issn = {1868-9221}, pages = {47 -- 57}, year = {2025}, subject = {K{\"u}nstliche Intelligenz}, language = {en} } @inproceedings{HuesenvonBergSteffens2025, author = {H{\"u}sen, Jonas and von Berg, Markus and Steffens, Jochen}, title = {Evaluating the Effectiveness of Virtual Listening Tests for Balanced Armature Headphone Drivers [Abstract]}, series = {DAS|DAGA 2025: 51st Annual Meeting on Acoustics, March 17-20, 2025, Copenhagen}, booktitle = {DAS|DAGA 2025: 51st Annual Meeting on Acoustics, March 17-20, 2025, Copenhagen}, publisher = {Deutsche Gesellschaft f{\"u}r Akustik e.V.}, address = {Berlin}, year = {2025}, subject = {Kopfh{\"o}rer}, language = {en} } @inproceedings{HuesenvonBergSteffens2025, author = {H{\"u}sen, Jonsa and von Berg, Markus and Steffens, Jochen}, title = {Evaluating the Effectiveness of Virtual Listening Tests for Balanced Armature Headphone Drivers}, series = {AES International Conference on Headphone Technology 2025 August 27-29, Espoo, Finland}, booktitle = {AES International Conference on Headphone Technology 2025 August 27-29, Espoo, Finland}, number = {3}, publisher = {Audio Engineering Society}, year = {2025}, language = {en} } @inproceedings{NeefHummel2000, author = {Neef, Matthias and Hummel, Dietrich}, title = {Euler solutions for a finite-span flapping wing}, series = {"Fixed, flapping and rotary wing vehicles at very low Reynolds numbers, Notre Dame, Indiana, USA}, booktitle = {"Fixed, flapping and rotary wing vehicles at very low Reynolds numbers, Notre Dame, Indiana, USA}, year = {2000}, language = {en} }