@inproceedings{EchternachtSchultze2018, author = {Echternacht, David and Schultze, Nico}, title = {Integriertes Asset Management als Basis einer Energiewendegerechten Instandhaltungs- und Investitionsstrategie}, series = {Anlagentechnik 2018: Anlagentechnik f{\"u}r elektrische Verteilungsnetze}, volume = {Anlagentechnik f{\"u}r elektrische Verteilungsnetze}, booktitle = {Anlagentechnik 2018: Anlagentechnik f{\"u}r elektrische Verteilungsnetze}, editor = {Cichowski, Rolf R{\"u}diger}, publisher = {EW Medien und Kongresse}, address = {Frankfurt am Main}, isbn = {9783802211669}, pages = {167 -- 173}, year = {2018}, language = {de} } @inproceedings{EchternachtStaggePriebeetal.2015, author = {Echternacht, David and Stagge, Hanno and Priebe, Jens and Wiernes, Pablo Ezequiel and Jagielski, Kai and Petri, Anne-Kathrin and Drießen, Sarah and Trevisan, Bianka and Digmayer, Claas and Oberst, Christian A. and Keysselitz, B{\"a}rbel and Kremer, Martin and Sieber, Sandra and Krapp, Stefan and Jakobs, Eva-Maria and Frenz, Martin and Lohrberg, Frank and Wachten, Kunibert and Moser, Albert}, title = {Modelling, Planning, Design and Evaluation of DC-Distribution Grids}, series = {International ETG Congress 2015 : die Energiewende ; blueprints for the new energy age ; proceedings ; November 17 - 18, 2015, World Conference Center, Bonn}, booktitle = {International ETG Congress 2015 : die Energiewende ; blueprints for the new energy age ; proceedings ; November 17 - 18, 2015, World Conference Center, Bonn}, publisher = {VDE-Verl.}, address = {Bonn}, pages = {289 -- 295}, year = {2015}, language = {en} } @inproceedings{GitisSauerMoseretal.2014, author = {Gitis, Alexander and Sauer, Dirk-Uwe and Moser, Albert and Echternacht, David and Kleimaier, Martin and Becker, Andreas and Aundrup, Thomas and Berthold, Andreas and Pokojski, Martin and Leuthold, Matthias and Rotering, Niklas}, title = {Dezentrale Energiespeicher: Einsatzm{\"o}glichkeiten, Bedarf und Wirtschaftlichkeit}, series = {VDE-Kongress 2014 - Smart Cities - Intelligente L{\"o}sungen f{\"u}r das Leben in der Zukunft 20.10.2014 - 21.10.2014 in Frankfurt am Main}, booktitle = {VDE-Kongress 2014 - Smart Cities - Intelligente L{\"o}sungen f{\"u}r das Leben in der Zukunft 20.10.2014 - 21.10.2014 in Frankfurt am Main}, publisher = {VDE}, address = {Frankfurt am Main}, pages = {1 -- 6}, year = {2014}, language = {de} } @inproceedings{KippeltRehtanzGitisetal.2015, author = {Kippelt, Stefan and Rehtanz, Christian and Gitis, Alexander Mihailovic and Leuthold, Matthias and Sauer, Dirk Uwe and Echternacht, David and Rotering, Niklas and Moser, Albert and Kleimaier, Martin and Loges, Hauke and Becker, Andreas and Aundrup, Thomas and Berthold, Andreas and Pokojski, Martin}, title = {Dezentrale Energiespeicher: Studie zu Stromspeichern in der Nieder- und Mittelspannungsebene}, series = {Von Smart Grids zu Smart Markets 2015 - Beitr{\"a}ge der ETG-Fachtagung 25.03.2015 - 26.03.2015 in Kassel, Deutschland}, booktitle = {Von Smart Grids zu Smart Markets 2015 - Beitr{\"a}ge der ETG-Fachtagung 25.03.2015 - 26.03.2015 in Kassel, Deutschland}, publisher = {ETG}, address = {Kassel}, year = {2015}, language = {de} } @inproceedings{LinnemannEchternachtBreueretal.2012, author = {Linnemann, Christian and Echternacht, David and Breuer, Christopher and Heuberger, Daniel and Moser, Albert}, title = {Ermittlung vorteilhafter HG{\"U}-Anschlussknoten}, series = {Smart Grid: Intelligente Energieversorgung der Zukunft ; Kongressbeit{\"a}ge ; 5. - 6. November 2012, Internationales Congresscenter Stuttgart (ICS)}, booktitle = {Smart Grid: Intelligente Energieversorgung der Zukunft ; Kongressbeit{\"a}ge ; 5. - 6. November 2012, Internationales Congresscenter Stuttgart (ICS)}, publisher = {VDE-Verl.}, address = {Berlin}, isbn = {978-3-8007-3446-7}, year = {2012}, language = {de} } @inproceedings{LinnemannEchternachtBreueretal.2011, author = {Linnemann, Christian and Echternacht, David and Breuer, Christopher and Moser, Albert}, title = {Modeling optimal redispatch for the European Transmission grid}, series = {2011 IEEE Trondheim PowerTech,19.06.2011 - 23.06.2011, Trondheim}, booktitle = {2011 IEEE Trondheim PowerTech,19.06.2011 - 23.06.2011, Trondheim}, publisher = {IEEE}, isbn = {978-1-4244-8418-8}, doi = {10.1109/PTC.2011.6019442}, pages = {1 -- 8}, year = {2011}, language = {en} } @inproceedings{NemeSeefeldtGottsteinetal.2014, author = {Neme, Christopher and Seefeldt, Friedrich and Gottstein, Meg and Echternacht, David and Moser, Albert and Weston, Frederick}, title = {The Positive Effects of Energy Efficiency on the German Electricity Sector: Peer-reviewed paper presented at IEPPEC 2014 International Energy Policies \& Programmes Evaluation Conference}, series = {15. International Energy Policies \& Programmes Evaluation Conference (IEPEC), Berlin, Deutschland, 09.09-11.09.2014}, booktitle = {15. International Energy Policies \& Programmes Evaluation Conference (IEPEC), Berlin, Deutschland, 09.09-11.09.2014}, address = {Berlin}, pages = {1 -- 16}, year = {2014}, language = {en} } @article{Braun2022, author = {Braun, Alexander}, title = {Automotive mass production of camera systems: Linking image quality to AI performance}, series = {tm - Technisches Messen}, journal = {tm - Technisches Messen}, publisher = {Walter de Gruyter}, issn = {2196-7113}, doi = {10.1515/teme-2022-0029}, year = {2022}, abstract = {Artificial intelligence methods based on machine learning or artificial neural networks have become indispensable in camera-based driver assistance systems, and also represent an essential building block for future autonomous driving. However, the great successes of these evaluation methods in environment perception and also driving planning are accompanied by equally great challenges in the validation and verification of these systems. One of the essential aspects for this is the required guaranteed safety of the functions under mass production conditions of the vehicles. This article explains this point of view using a detailed example from the field of camera-based driver assistance systems: the determination of inspection limits at the end of the production line. The camera is one of the most important sensor modalities for vehicle environment sensing and as such, the quality of the camera systems plays a key role in the safety argumentation of the overall system. Several illustrative application examples (role of simulations, calibration, influence of the windshield) will be presented. The basic ideas presented can be well transferred to the other sensor modalities (lidar, radar, ToF, etc.). The investigations/evidence show that doubts are allowed whether or how fast autonomous driving on level L4/5 will take hold as robotaxis or - even more challenging - in private ownership on a larger scale.}, language = {en} } @inproceedings{BalzerHannemannWunderlichetal.2005, author = {Balzer, Chr. and Hannemann, Th. and Wunderlich, Chr. and Braun, Alexander and Ettler, M. and Paape, Chr. and Neuhauser, W.}, title = {Efficient photoionisation, preparation and coherent manipulation of trapped /sup 171/Yb/sup +/-ions}, series = {EQEC '05. European Quantum Electronics Conference, 12-17 June 2005, Munich}, booktitle = {EQEC '05. European Quantum Electronics Conference, 12-17 June 2005, Munich}, publisher = {IEEE}, isbn = {0-7803-8973-5}, doi = {10.1109/EQEC.2005.1567474}, pages = {308}, year = {2005}, language = {en} } @phdthesis{Braun2007, author = {Braun, Alexander}, title = {Addressing Single Yb+ Ions: A new scheme for quantum computing in linear ion traps}, publisher = {Cuvillier Verlag}, address = {G{\"o}ttingen}, isbn = {978-3-86727-276-6}, pages = {169}, year = {2007}, language = {en} } @article{WittpahlZakourLehmannetal.2018, author = {Wittpahl, Christian and Zakour, Hatem Ben and Lehmann, Matthias and Braun, Alexander}, title = {Realistic Image Degradation with Measured PSF}, series = {Electronic Imaging, Autonomous Vehicles and Machines 2018}, journal = {Electronic Imaging, Autonomous Vehicles and Machines 2018}, number = {17}, publisher = {Society for Imaging Science and Technology}, issn = {2470-1173}, doi = {10.2352/ISSN.2470-1173.2018.17.AVM-149}, pages = {149}, year = {2018}, language = {en} } @article{TsengMoslehMannanetal.2021, author = {Tseng, Ethan and Mosleh, Ali and Mannan, Fahim and St-Arnaud, Karl and Sharma, Avinash and Peng, Yifan and Braun, Alexander and Nowrouzezahrai, Derek and Lalonde, Jean-Fran{\c{c}}ois and Heide, Felix}, title = {Differentiable Compound Optics and Processing Pipeline Optimization for End-to-end Camera Design}, series = {ACM Transactions on Graphics}, volume = {40}, journal = {ACM Transactions on Graphics}, number = {2}, publisher = {Association for Computing Machinery}, address = {New York, NY, USA}, issn = {1557-7368}, doi = {10.1145/3446791}, pages = {1 -- 19}, year = {2021}, abstract = {Most modern commodity imaging systems we use directly for photography--or indirectly rely on for downstream applications--employ optical systems of multiple lenses that must balance deviations from perfect optics, manufacturing constraints, tolerances, cost, and footprint. Although optical designs often have complex interactions with downstream image processing or analysis tasks, today's compound optics are designed in isolation from these interactions. Existing optical design tools aim to minimize optical aberrations, such as deviations from Gauss' linear model of optics, instead of application-specific losses, precluding joint optimization with hardware image signal processing (ISP) and highly parameterized neural network processing. In this article, we propose an optimization method for compound optics that lifts these limitations. We optimize entire lens systems jointly with hardware and software image processing pipelines, downstream neural network processing, and application-specific end-to-end losses. To this end, we propose a learned, differentiable forward model for compound optics and an alternating proximal optimization method that handles function compositions with highly varying parameter dimensions for optics, hardware ISP, and neural nets. Our method integrates seamlessly atop existing optical design tools, such as Zemax. We can thus assess our method across many camera system designs and end-to-end applications. We validate our approach in an automotive camera optics setting--together with hardware ISP post processing and detection--outperforming classical optics designs for automotive object detection and traffic light state detection. For human viewing tasks, we optimize optics and processing pipelines for dynamic outdoor scenarios and dynamic low-light imaging. We outperform existing compartmentalized design or fine-tuning methods qualitatively and quantitatively, across all domain-specific applications tested.}, language = {en} } @inproceedings{MuellerLehmannBraun2020, author = {Mueller, Patrick and Lehmann, Matthias and Braun, Alexander}, title = {Simulating tests to test simulation}, series = {IS\&T International Symposium on Electronic Imaging 2020: Autonomous Vehicles and Machines, 26 January 2020 — 30 January 2020, Burlingame, CA, USA}, volume = {2020}, booktitle = {IS\&T International Symposium on Electronic Imaging 2020: Autonomous Vehicles and Machines, 26 January 2020 — 30 January 2020, Burlingame, CA, USA}, number = {16}, publisher = {Society for Imaging Science and Technology}, doi = {10.2352/ISSN.2470-1173.2020.16.AVM-149}, year = {2020}, language = {en} } @article{KrebsMuellerBraun2021, author = {Krebs, Christian and M{\"u}ller, Patrick and Braun, Alexander}, title = {Impact of Windshield Optical Aberrations on Visual Range Camera Based Classification Tasks Performed by CNNs}, series = {London Imaging Meeting}, volume = {2021}, journal = {London Imaging Meeting}, number = {1}, publisher = {Ingenta connect}, isbn = {0-89208-346-6}, issn = {2694-118X}, doi = {10.2352/issn.2694-118X.2021.LIM-83}, pages = {83 -- 87}, year = {2021}, language = {de} } @inproceedings{JohanningBraunElmanetal.2007, author = {Johanning, M. and Braun, Alexander and Elman, V. and Wunderlich, Chr. and Neuhauser, W.}, title = {Individual Addressing with Trapped Yb+ Ions}, series = {2007 European Conference on Lasers and Electro-Optics and the International Quantum Electronics Conference, 17.06.2007 - 22.06.2007, Munich, Germany}, booktitle = {2007 European Conference on Lasers and Electro-Optics and the International Quantum Electronics Conference, 17.06.2007 - 22.06.2007, Munich, Germany}, publisher = {IEEE}, address = {M{\"u}nchen}, isbn = {978-1-4244-0930-3}, doi = {10.1109/CLEOE-IQEC.2007.4386787}, pages = {1}, year = {2007}, language = {en} } @article{JohanningBraunTimoneyetal.2009, author = {Johanning, M. and Braun, Alexander and Timoney, N. and Elman, V. and Neuhauser, W. and Wunderlich, Chr}, title = {Individual addressing of trapped ions and coupling of motional and spin states using RF radiation}, series = {Physical review letters}, volume = {102}, journal = {Physical review letters}, number = {7}, publisher = {American Physical Society}, issn = {1079-7114}, doi = {10.1103/PhysRevLett.102.073004}, year = {2009}, abstract = {Individual electrodynamically trapped and laser cooled ions are addressed in frequency space using radio-frequency radiation in the presence of a static magnetic field gradient. In addition, an interaction between motional and spin states induced by an rf field is demonstrated employing rf optical double resonance spectroscopy. These are two essential experimental steps towards realizing a novel concept for implementing quantum simulations and quantum computing with trapped ions.}, language = {en} } @article{JohanningBraunEiteneueretal.2011, author = {Johanning, M. and Braun, Alexander and Eiteneuer, D. and Paape, C. and Balzer, C. and Neuhauser, W. and Wunderlich, C.}, title = {Resonance-enhanced isotope-selective photoionization of YbI for ion trap loading}, series = {Applied Physics B}, volume = {103}, journal = {Applied Physics B}, number = {2}, publisher = {Springer Nature}, issn = {1432-0649}, doi = {10.1007/s00340-011-4502-7}, pages = {327 -- 338}, year = {2011}, language = {en} } @article{BraunKornmesserBeushausen2005, author = {Braun, Alexander and Kornmesser, Christoph and Beushausen, Volker}, title = {Simultaneous spatial and spectral imaging of lasing droplets}, series = {Journal of the Optical Society of America}, volume = {22}, journal = {Journal of the Optical Society of America}, number = {9}, publisher = {Optical Society of America}, issn = {0030-3941}, doi = {10.1364/josaa.22.001772}, pages = {1772 -- 1779}, year = {2005}, abstract = {We present an experimental technique that allows the simultaneous spatial imaging and spectral analysis of falling droplets that exhibit lasing. Single droplet investigations serve as, among other purposes, a preliminary study for spray and combustion researchers. The described setup provides a valuable tool for the evaluation of microdroplet investigations with laser-spectroscopic techniques that rely on laser-induced fluorescence (LIF) or similar spectroscopical phenomena. The emphasis is that both spatial and spectral information are obtained from single-shot images of a falling droplet. Furthermore, combining spatial imaging and a spatially resolving optical multichannel analyzer makes a pointwise rastering of the droplets spectrum possible. This allows for the (almost) unambiguous determination of sources of influence on the spectrum of these droplets-such as geometrical distortion and lasing, nondissolved tracer lumps, and similar phenomena. Although the focus is on the experimental technique itself, we supplement detailed studies of lasing in falling microdroplets. These results were obtained with the aim of developing a system for measuring temperature distributions in droplets and sprays. In the light of these results the practice of calibrating a droplets spectrum by use of a bulk liquid sample needs to be critically reviewed.}, language = {en} } @misc{Braun2001, author = {Braun, Alexander}, title = {Laserspektroskopische Messverfahren zur Temperaturbestimmung in Sprays}, publisher = {Georg-August-Universit{\"a}t G{\"o}ttingen}, address = {G{\"o}ttingen}, organization = {Georg-August-Universit{\"a}t G{\"o}ttingen}, year = {2001}, language = {de} } @article{BalzerBraunHannemannetal.2006, author = {Balzer, Chr. and Braun, Alexander and Hannemann, T. and Paape, Chr. and Ettler, M. and Neuhauser, W. and Wunderlich, Chr.}, title = {Electrodynamically trapped Yb+ ions for quantum information processing}, series = {Physical Review A}, volume = {73}, journal = {Physical Review A}, number = {4}, publisher = {American Physical Society}, issn = {2469-9934}, doi = {10.1103/PhysRevA.73.041407}, year = {2006}, language = {en} } @article{HeizmannBraunGlitzneretal.2022, author = {Heizmann, Michael and Braun, Alexander and Glitzner, Markus and G{\"u}nther, Matthias and Hasna, G{\"u}nther and Kl{\"u}ver, Christina and Krooß, Jakob and Marquardt, Erik and Overdick, Michael and Ulrich, Markus}, title = {Implementing machine learning: chances and challenges}, series = {at - Automatisierungstechnik}, volume = {70}, journal = {at - Automatisierungstechnik}, number = {1}, publisher = {De Gruyter}, address = {Berlin}, issn = {2196-677X}, doi = {10.1515/auto-2021-0149}, pages = {90 -- 101}, year = {2022}, language = {en} } @incollection{ChristmannBusboomFeigeetal.2020, author = {Christmann, Simon and Busboom, Imke and Feige, Volker K.S. and Haehnel, Hartmut}, title = {Towards Automated Quality Inspection Using a Semi-Mobile Robotized Terahertz System}, series = {2020 Third International Workshop on Mobile Terahertz Systems (IWMTS)}, booktitle = {2020 Third International Workshop on Mobile Terahertz Systems (IWMTS)}, publisher = {IEEE}, address = {Essen}, isbn = {978-1-7281-5598-2}, doi = {10.1109/IWMTS49292.2020.9166259}, pages = {1 -- 5}, year = {2020}, language = {en} } @article{SchullerVlasenkoEybenetal.2010, author = {Schuller, Bjorn and Vlasenko, Bogdan and Eyben, Florian and Wollmer, Martin and Stuhlsatz, Andr{\´e} and Wendemuth, Andreas and Rigoll, Gerhard}, title = {Cross-Corpus Acoustic Emotion Recognition: Variances and Strategies}, series = {IEEE Transactions on Affective Computing}, volume = {1}, journal = {IEEE Transactions on Affective Computing}, number = {2}, publisher = {IEEE}, doi = {10.1109/t-affc.2010.8}, pages = {119 -- 131}, year = {2010}, language = {en} } @article{LyalinaLangmannKrisilov2011, author = {Lyalina, Yuliya and Langmann, Reinhard and Krisilov, V.}, title = {The Interaction Model in iLearning Environments and its Use in the Smart Lab Concept}, series = {International Journal of Online Engineering}, volume = {7}, journal = {International Journal of Online Engineering}, number = {4}, publisher = {iJOE}, doi = {10.3991/ijoe.v7i4.1793}, year = {2011}, language = {en} } @article{QuevalGottkehaskamp2015, author = {Queval, Loic and Gottkehaskamp, Raimund}, title = {Analytical Field Calculation of Modulated Double Helical Coils}, series = {IEEE Transactions on Applied Superconductivity}, volume = {25}, journal = {IEEE Transactions on Applied Superconductivity}, number = {6}, publisher = {IEEE}, doi = {10.1109/tasc.2015.2477377}, pages = {1 -- 7}, year = {2015}, language = {en} } @article{Franz1996, author = {Franz, J{\"u}rgen}, title = {Benefits of Communication Methods in Environmental Protection}, series = {IETE Technical Review}, volume = {13}, journal = {IETE Technical Review}, number = {3}, publisher = {Taylor \& Francis}, doi = {10.1080/02564602.1996.11416600}, pages = {153 -- 162}, year = {1996}, language = {en} } @article{JainFranz2004, author = {Jain, V. K. and Franz, J. H.}, title = {Some Design Issues in Infrared Wireless Networks}, series = {IETE Technical Review}, volume = {21}, journal = {IETE Technical Review}, number = {5}, publisher = {Taylor \& Francis}, doi = {10.1080/02564602.2004.11417161}, pages = {335 -- 343}, year = {2004}, language = {en} } @article{HeinickeBaeklerHehl2005, author = {Heinicke, Christian and Baekler, Peter and Hehl, Friedrich W.}, title = {Einstein-aether theory, violation of Lorentz invariance, and metric-affine gravity}, series = {Physical Review D}, volume = {72}, journal = {Physical Review D}, number = {2}, publisher = {APS}, doi = {10.1103/physrevd.72.025012}, year = {2005}, language = {en} } @article{BaeklerHehl2006, author = {Baekler, Peter and Hehl, Friedrich W.}, title = {ROTATING BLACK HOLES IN METRIC-AFFINE GRAVITY}, series = {International Journal of Modern Physics D}, volume = {15}, journal = {International Journal of Modern Physics D}, number = {5}, publisher = {World Scientific}, doi = {10.1142/s0218271806008589}, pages = {635 -- 668}, year = {2006}, language = {en} } @article{Langmann2010, author = {Langmann, Reinhard}, title = {Distributed Web-Based Control System}, series = {International Journal of Online Engineering (iJOE)}, volume = {6}, journal = {International Journal of Online Engineering (iJOE)}, number = {3}, publisher = {iJOE}, doi = {10.3991/ijoe.v6i3.1345}, year = {2010}, language = {en} } @article{BaeklerHehlNester2011, author = {Baekler, Peter and Hehl, Friedrich W. and Nester, James M.}, title = {Poincar{\´e} gauge theory of gravity: Friedman cosmology with even and odd parity modes: Analytic part}, series = {Physical Review D}, volume = {83}, journal = {Physical Review D}, number = {2}, publisher = {APS}, doi = {10.1103/physrevd.83.024001}, year = {2011}, language = {en} } @article{BaeklerHehl2011, author = {Baekler, Peter and Hehl, Friedrich W.}, title = {Beyond Einstein-Cartan gravity: quadratic torsion and curvature invariants with even and odd parity including all boundary terms}, series = {Classical and Quantum Gravity}, volume = {28}, journal = {Classical and Quantum Gravity}, number = {21}, publisher = {IOP}, doi = {10.1088/0264-9381/28/21/215017}, year = {2011}, language = {en} } @article{LangmannStiller2015, author = {Langmann, Reinhard and Stiller, Michael}, title = {Industrial Cloud - Status und Ausblick}, series = {HMD Praxis der Wirtschaftsinformatik}, volume = {52}, journal = {HMD Praxis der Wirtschaftsinformatik}, number = {5}, publisher = {Springer Nature}, doi = {10.1365/s40702-015-0162-0}, pages = {647 -- 664}, year = {2015}, language = {de} } @article{RichterSteenmannSchellscheidtetal.2019, author = {Richter, Jessica and Steenmann, Anna and Schellscheidt, Benjamin and Licht, Thomas}, title = {On-Chip Diffusion Bonding creates Stable Interconnections Usable at Temperatures over 300°C}, series = {International Symposium on Microelectronics}, volume = {2019}, journal = {International Symposium on Microelectronics}, number = {1}, publisher = {IMAPS}, organization = {IMAPS}, doi = {10.4071/2380-4505-2019.1.000530}, pages = {000530 -- 000534}, year = {2019}, language = {en} } @article{KagermannLangRoscher2020, author = {Kagermann, Dominik and Lang, Kati and Roscher, Ang{\´e}lique}, title = {Mehr Lernerfolg durch die Digitalisierung der Lehre}, series = {Sales Excellence}, volume = {29}, journal = {Sales Excellence}, number = {11}, publisher = {Springer Fachmedien}, doi = {10.1007/s35141-020-0392-9}, pages = {20 -- 23}, year = {2020}, language = {de} } @article{HeizmannBraunHuetteletal.2020, author = {Heizmann, Michael and Braun, Alexander and H{\"u}ttel, Markus and Kl{\"u}ver, Christina and Marquardt, Erik and Overdick, Michael and Ulrich, Markus}, title = {Artificial intelligence with neural networks in optical measurement and inspection systems}, series = {at - Automatisierungstechnik}, volume = {68}, journal = {at - Automatisierungstechnik}, number = {6}, publisher = {De Gruyter}, doi = {10.1515/auto-2020-0006}, pages = {477 -- 487}, year = {2020}, language = {en} } @article{DiGioiaBrownNieetal.2018, author = {Di Gioia, Antonio and Brown, Ian P. and Nie, Yue and Knippel, Ryan and Ludois, Daniel C. and Dai, Jiejian and Hagen, Skyler and Alteheld, Christian}, title = {Design and Demonstration of a Wound Field Synchronous Machine for Electric Vehicle Traction With Brushless Capacitive Field Excitation}, series = {IEEE Transactions on Industry Applications}, volume = {54}, journal = {IEEE Transactions on Industry Applications}, number = {2}, publisher = {IEEE}, doi = {10.1109/tia.2017.2784799}, pages = {1390 -- 1403}, year = {2018}, abstract = {This paper describes the modeling, optimization, mechanical design, and experimental characterization of a high power density wound field synchronous machine (WFSM) for electric vehicle traction applications. The WFSM is designed for brushless rotor field excitation using an axial flux hydrodynamic capacitive power coupler (CPC). The flexible design environment, which was used for large-scale multiobjective optimization of the WFSM, is described. A prototype WFSM, spray cooled with automatic transmission fluid, with an 80-kW output at a base speed of 4000 r/min has been tested. The prototyped WFSM achieves volumetric torque and power densities of 17.22 N·m/L and 7.19 kW/L referred to the envelope cylindrical volume of the active materials plus spray cooling rings. The specific torque and power densities are 4.69 N·m/kg and 1.95 kW/kg referred to the mass of the active materials and the shaft. The prototyped CPC provided up to 1-kW excitation power with a mass 600 g and volume of 0.271 L.}, language = {en} } @inproceedings{MuellerLehmannBraun2019, author = {M{\"u}ller, Patrick and Lehmann, Matthias and Braun, Alexander}, title = {Optical quality metrics for image restoration}, series = {Digital Optical Technologies 2019}, volume = {Proceedings, Vol. 11062}, booktitle = {Digital Optical Technologies 2019}, editor = {Kress, Bernard C. and Schelkens, Peter}, address = {Munich}, organization = {International Society for Optics and Photonics}, doi = {10.1117/12.2528100}, pages = {1106214}, year = {2019}, abstract = {Image restoration is a process used to remove blur (from different sources like object motion or aberrations) from images by either non-blind or blind-deconvolution. The metrics commonly used to quantify the restoration process are peak signal-to-noise ratio (PSNR) and structural similarity index measure (SSIM). Often only a small sample of test images are used (like Lena or the camera guy). In optical design research PSNR and SSIM are not normally used, here image quality metrics based on linear system theory (e.g. modulation transfer function, MTF) are used to quantify optical errors like spherical or chromatic aberration. In this article we investigate how different image restoration algorithms can be quantified by applying image quality metrics. We start with synthetic image data that is used in camera test stands (e.g. Siemens star etc.), apply two different spatially variant degradation algorithms, and restore the original image by a direct method (Wiener filtering within sub-images), and by an iterative method (alternating direction method of multipliers, ADMM). Afterwards we compare the quality metrics (like MTF curves) for the original, the degraded and the restored image. As a first result we show that restoration algorithms sometimes fail in dealing with non-natural scenes, e.g. slanted-edge targets. Further, these first results indicate a correlation between degradation and restoration, i.e. the restoration algorithms are not capable of removing the optically relevant errors introduced by the degradation, a fact neither visible nor available from the PSNR values. We discuss the relevance in the context of the automotive industry, where image restoration may yield distinct advantages for camera-based applications, but testing methods rely on the used image quality metrics.}, language = {en} } @article{LehmannWittpahlZakouretal.2019, author = {Lehmann, Matthias and Wittpahl, Christian and Zakour, Hatem Ben and Braun, Alexander}, title = {Resolution and accuracy of nonlinear regression of point spread function with artificial neural networks}, series = {Optical Engineering}, volume = {58}, journal = {Optical Engineering}, number = {4}, publisher = {SPIE}, issn = {0091-3286}, doi = {10.1117/1.oe.58.4.045101}, pages = {045101}, year = {2019}, abstract = {We had already demonstrated a numerical model for the point spread function (PSF) of an optical system that can efficiently model both the experimental measurements and the lens design simulations of the PSF. The novelty lies in the portability and the parameterization of this model, which allow for completely new ways to validate optical systems, which is especially interesting not only for mass production optics such as in the automotive industry but also for ophthalmology. The numerical basis for this model is a nonlinear regression of the PSF with an artificial neural network (ANN). After briefly describing both the principle and the applications of the model, we then discuss two optically important aspects: the spatial resolution and the accuracy of the model. Using mean squared error (MSE) as a metric, we vary the topology of the neural network, both in the number of neurons and in the number of hidden layers. Measurement and simulation of a PSF can have a much higher spatial resolution than the typical pixel size used in current camera sensors. We discuss the influence this has on the topology of the ANN. The relative accuracy of the averaged pixel MSE is below 10  -  4, thus giving confidence that the regression does indeed model the measurement data with good accuracy. This article is only the starting point, and we propose several research avenues for future work.}, language = {en} } @article{LehmannWittpahlZakouretal.2019, author = {Lehmann, Matthias and Wittpahl, Christian and Zakour, Hatem Ben and Braun, Alexander}, title = {Modeling realistic optical aberrations to reuse existing drive scene recordings for autonomous driving validation}, series = {Journal of Electronic Imaging}, volume = {28}, journal = {Journal of Electronic Imaging}, number = {1}, publisher = {SPIE}, issn = {1560-229X}, doi = {10.1117/1.JEI.28.1.013005}, pages = {013005}, year = {2019}, abstract = {Training autonomous vehicles requires lots of driving sequences in all situations. Collecting and labeling these drive scenes is a very time-consuming and expensive process. Currently, it is not possible to reuse these drive scenes with different optical properties, because there exists no numerically efficient model for the transfer function of the optical system. We present a numerical model for the point spread function (PSF) of an optical system that can efficiently model both experimental measurements and lens design simulations of the PSF. The numerical basis for this model is a nonlinear regression of the PSF with an artificial neural network. The novelty lies in the portability and the parameterization of this model. We present a lens measurement series, yielding a numerical function for the PSF that depends only on the parameters defocus, field, and azimuth. By convolving existing images and videos with this PSF, we generate images as if seen through the measured lens. The methodology applies to any optical scenario, but we focus on the context of autonomous driving, where the quality of the detection algorithms depends directly on the optical quality of the used camera system. With this model, it is possible to reuse existing recordings, with the potential to avoid millions of test drive miles. The parameterization of the optical model allows for a method to validate the functional and safety limits of camera-based advanced driver assistance systems based on the real, measured lens actually used in the product.}, language = {en} } @inproceedings{LehmannWittpahlZakouretal.2018, author = {Lehmann, Matthias and Wittpahl, Christian and Zakour, Hatem Ben and Braun, Alexander}, title = {Resolution and accuracy of non-linear regression of PSF with artificial neural networks}, series = {SPIE Optical Systems Design: Optical Instrument Science, Technology, and Applications, 2018, Frankfurt, Germany}, volume = {Proc. SPIE, Vol. 10695}, booktitle = {SPIE Optical Systems Design: Optical Instrument Science, Technology, and Applications, 2018, Frankfurt, Germany}, number = {106950C}, editor = {Haverkamp, Nils and Youngworth, Richard N.}, publisher = {International Society for Optics and Photonics}, address = {Frankfurt}, organization = {International Society for Optics and Photonics}, doi = {10.1117/12.2313144}, pages = {52 -- 63}, year = {2018}, abstract = {In a previous work we have demonstrated a novel numerical model for the point spread function (PSF) of an optical system that can efficiently model both experimental measurements and lens design simulations of the PSF. The novelty lies in the portability and the parameterization of this model, which allows for completely new ways to validate optical systems, which is especially interesting for mass production optics like in the automotive industry, but also for ophtalmology. The numerical basis for this model is a non-linear regression of the PSF with an artificial neural network (ANN). In this work we examine two important aspects of this model: the spatial resolution and the accuracy of the model. Measurement and simulation of a PSF can have a much higher resolution then the typical pixel size used in current camera sensors, especially those for the automotive industry. We discuss the influence this has on on the topology of the ANN and the final application where the modeled PSF is actually used. Another important influence on the accuracy of the trained ANN is the error metric which is used during training. The PSF is a distinctly non-linear function, which varies strongly over field and defocus, but nonetheless exhibits strong symmetries and spatial relations. Therefore we examine different distance and similarity measures and discuss its influence on the modeling performance of the ANN.}, language = {en} }