@article{DoblerWalterKnopfetal., author = {Dobler, Barbara and Walter, Cornelia and Knopf, Antje and Fabri, Daniella and L{\"o}schel, Rainer and Polednik, Martin and Schneider, Frank and Wenz, Frederik and Lohr, Frank}, title = {Optimization of extracranial stereotactic radiation therapy of small lung lesions using accurate dose calculation algorithms}, series = {Radiation Oncology}, volume = {1}, journal = {Radiation Oncology}, publisher = {BMC ; Springer}, doi = {10.1186/1748-717X-1-45}, pages = {11}, abstract = {BACKGROUND The aim of this study was to compare and to validate different dose calculation algorithms for the use in radiation therapy of small lung lesions and to optimize the treatment planning using accurate dose calculation algorithms. METHODS A 9-field conformal treatment plan was generated on an inhomogeneous phantom with lung mimics and a soft tissue equivalent insert, mimicking a lung tumor. The dose distribution was calculated with the Pencil Beam and Collapsed Cone algorithms implemented in Masterplan (Nucletron) and the Monte Carlo system XVMC and validated using Gafchromic EBT films. Differences in dose distribution were evaluated. The plans were then optimized by adding segments to the outer shell of the target in order to increase the dose near the interface to the lung. RESULTS The Pencil Beam algorithm overestimated the dose by up to 15\% compared to the measurements. Collapsed Cone and Monte Carlo predicted the dose more accurately with a maximum difference of -8\% and -3\% respectively compared to the film. Plan optimization by adding small segments to the peripheral parts of the target, creating a 2-step fluence modulation, allowed to increase target coverage and homogeneity as compared to the uncorrected 9 field plan. CONCLUSION The use of forward 2-step fluence modulation in radiotherapy of small lung lesions allows the improvement of tumor coverage and dose homogeneity as compared to non-modulated treatment plans and may thus help to increase the local tumor control probability. While the Collapsed Cone algorithm is closer to measurements than the Pencil Beam algorithm, both algorithms are limited at tissue/lung interfaces, leaving Monte-Carlo the most accurate algorithm for dose prediction.}, language = {en} } @article{ZygmanskiHoegeleCormacketal., author = {Zygmanski, Piotr and H{\"o}gele, Wolfgang and Cormack, Robert and Chin, Lee and L{\"o}schel, Rainer}, title = {A volumetric-modulated arc therapy using sub-conformal dynamic arc with a monotonic dynamic multileaf collimator modulation}, series = {Physics in medicine and biology}, volume = {53}, journal = {Physics in medicine and biology}, number = {22}, publisher = {IOP Publishing}, doi = {10.1088/0031-9155/53/22/009}, pages = {6395 -- 6417}, abstract = {We present a new dose delivery scheme utilizing sub-conformal dynamic arc (sub-CD-ARC) with a dynamic multileaf collimator (dMLC) modulation in a single rotation. In sub-conformal delivery, a MLC aperture conforms not to the whole target but to its portion, simultaneously completely avoiding organs at risk (OARs). In CD-ARC therapy, the dose deposition level depends on the target width and distance to the axis of rotation, and therefore the use of multiple arcs is necessary to achieve a uniform dose within the target in 3D. In our delivery scheme, the dose deposition variations symptomatic of non-modulating sub-CD-ARC are compensated for in 3D by a quasi-periodic monotonic dMLC modulation. For this reason, we call this scheme sub-conformal dynamic modulated arc (sub-CD-MARC) therapy. The advantage of using such a modulation is that MLC leaf motion has just a few control points, and that an inverse planning problem is reduced to a linear equation problem with a few unknown parameters, which have clear physical meaning. We show the general dosimetric properties of sub-CD-ARC and sub-CD-MARC for a specific geometry of the target and OARs (rotational symmetry with varying inner and outer radii along the axis of rotation). In addition, we present numerical results of sub-CD-MARC inverse planning optimization.}, language = {en} } @article{HoegeleLoeschelZygmanski, author = {Hoegele, W. and L{\"o}schel, Rainer and Zygmanski, Piotr}, title = {An alternative VMAT with prior knowledge about the type of leaf motion utilizing projection method for concave targets}, series = {Medical physics}, volume = {36}, journal = {Medical physics}, number = {8}, publisher = {American Association of Physicists in Medicine}, doi = {10.1118/1.3173815}, pages = {3764 -- 3774}, abstract = {The authors present an alternative approach to inverse planning optimization and apply it to volumetric modulated are therapy (VMAT) in one rotation with a prior knowledge about the type of leaf motions. The optimization is based on the projection theorem in inner product spaces. MLC motion is directly considered in the optimization, thus avoiding leaf segmentation characteristic of IMRT optimization. In this work they realize the method for concave irregular targets encompassing an organ at risk leading to a repetitive MLC motion pattern. Applying the projection theorem leads to a noniterative optimization method and reduces to solving few systems of linear equations with small numbers of dimensions. The solution of the inverse problem is unique, and false minima are naturally excluded. They divided the full rotation into about 50 short arc segments and for each segment decomposed dose into separate contributions related to stages of MLC motion. This results generally in an inverse problem with just four free parameters per arc segment. Practically three degrees of freedom will be used for the purpose of a constant angular speed of the gantry. Therefore the total number of degrees of freedom for a 3D problem is about 3 x 50 x number of collimator leaf pairs for irradiating the whole target volume in one rotation. Two 2D and one 3D concave target volumes are applied for a slice by slice optimization. A 6 MV photon beam model is used, including realistic scattering and attenuation, and a maximal leaf velocity of 3 cm/s is regarded. The resulting dose distributions cover the PTVs very well and have maxima at about 108\% of dose in the PTVs. The OAR is spared very strong in all cases. As a result of optimization, the MLC apertures are repetitively opening and closing and can be interpreted in an intuitive way. Applying the projection method for this knowledge-based VMAT delivery scheme for concave target volumes is an alternative technique for dose optimization. There are several properties, such as uniqueness of MLC motions and their continuous dependence on geometry and prescribed dose, that make this approach interesting to inverse planning. This method is still in an investigational stage, but promising results are presented. In future work it will be extended directly (without conceptual changes) in several directions to be more clinically applicable.}, language = {en} } @article{DoblerStreckKleinetal., author = {Dobler, Barbara and Streck, Natalia and Klein, Elisabeth and L{\"o}schel, Rainer and Haertl, Petra Maria and K{\"o}lbl, Oliver}, title = {Hybrid plan verification for intensity-modulated radiation therapy (IMRT) using the 2D ionization chamber array I'mRT MatriXX--a feasibility study}, series = {Physics in medicine and biology}, volume = {55}, journal = {Physics in medicine and biology}, number = {2}, publisher = {IOP Publishing}, doi = {10.1088/0031-9155/55/2/N02}, pages = {N39 -- N55}, abstract = {The 2D ionization chamber array I'mRT MatriXX (IBA, Schwarzenbruck, Germany) has been developed for absolute 2D dosimetry and verification of intensity-modulated radiation therapy (IMRT) for perpendicular beam incidence. The aim of this study is to evaluate the applicability of I'mRT MatriXX for oblique beam incidence and hybrid plan verification of IMRT with original gantry angles. For the assessment of angular dependence, open fields with gantry angles in steps of 10 degrees were calculated on a CT scan of I'mRT MatriXX. For hybrid plan verification, 17 clinical IMRT plans and one rotational plan were used. Calculations were performed with pencil beam (PB), collapsed cone (CC) and Monte Carlo (MC) methods, which had been previously validated. Measurements were conducted on an Elekta SynergyS linear accelerator. To assess the potential and limitations of the system, gamma evaluation was performed with different dose tolerances and distances to agreement. Hybrid plan verification passed the gamma test with 4\% dose tolerance and 3 mm distance to agreement in all cases, in 82-88\% of the cases for tolerances of 3\%/3 mm, and in 59-76\% of the cases if 3\%/2 mm were used. Separate evaluation of the low dose and high dose regions showed that I'mRT MatriXX can be used for hybrid plan verification of IMRT plans within 3\% dose tolerance and 3 mm distance to agreement with a relaxed dose tolerance of 4\% in the low dose region outside the multileaf collimator (MLC).}, language = {en} } @article{HoegeleLoeschelMerkleetal., author = {Hoegele, W. and L{\"o}schel, Rainer and Merkle, N. and Zygmanski, Piotr}, title = {An efficient inverse radiotherapy planning method for VMAT using quadratic programming optimization}, series = {Medical physics}, volume = {39}, journal = {Medical physics}, number = {1}, publisher = {American Association of Physicists in Medicine}, doi = {10.1118/1.3671922}, pages = {444 -- 454}, abstract = {PURPOSE The purpose of this study is to investigate the feasibility of an inverse planning optimization approach for the Volumetric Modulated Arc Therapy (VMAT) based on quadratic programming and the projection method. The performance of this method is evaluated against a reference commercial planning system (eclipse(TM) for rapidarc(TM)) for clinically relevant cases. METHODS The inverse problem is posed in terms of a linear combination of basis functions representing arclet dose contributions and their respective linear coefficients as degrees of freedom. MLC motion is decomposed into basic motion patterns in an intuitive manner leading to a system of equations with a relatively small number of equations and unknowns. These equations are solved using quadratic programming under certain limiting physical conditions for the solution, such as the avoidance of negative dose during optimization and Monitor Unit reduction. The modeling by the projection method assures a unique treatment plan with beneficial properties, such as the explicit relation between organ weightings and the final dose distribution. Clinical cases studied include prostate and spine treatments. The optimized plans are evaluated by comparing isodose lines, DVH profiles for target and normal organs, and Monitor Units to those obtained by the clinical treatment planning system eclipse(TM). RESULTS The resulting dose distributions for a prostate (with rectum and bladder as organs at risk), and for a spine case (with kidneys, liver, lung and heart as organs at risk) are presented. Overall, the results indicate that similar plan qualities for quadratic programming (QP) and rapidarc(TM) could be achieved at significantly more efficient computational and planning effort using QP. Additionally, results for the quasimodo phantom [Bohsung et al., "IMRT treatment planning: A comparative inter-system and inter-centre planning exercise of the estro quasimodo group," Radiother. Oncol. 76(3), 354-361 (2005)] are presented as an example for an extreme concave case. CONCLUSION Quadratic programming is an alternative approach for inverse planning which generates clinically satisfying plans in comparison to the clinical system and constitutes an efficient optimization process characterized by uniqueness and reproducibility of the solution.}, language = {en} } @article{SchoepfIselerSausele, author = {Sch{\"o}pf, Nicolas and Iseler, K. and Sausele, I.}, title = {Persistenz und Verschwinden. P{\"a}dagogische Organisationen im historischen Kontext}, series = {Zeitschrift f{\"u}r Soziologie der Erziehung und Sozialisation}, volume = {27}, journal = {Zeitschrift f{\"u}r Soziologie der Erziehung und Sozialisation}, number = {4}, publisher = {Beltz Juventa}, issn = {1436-1957}, pages = {442 -- 447}, language = {de} } @article{Zuerner, author = {Z{\"u}rner, Christian}, title = {Religi{\"o}se Bildung in der s{\"a}kularisierten Gesellschaft. Grundsatz{\"u}berlegungen mit Bezug auf den Philosophen J{\"u}rgen Habermas}, series = {Freies Christentum : auf der Suche nach neuen Wegen}, volume = {59}, journal = {Freies Christentum : auf der Suche nach neuen Wegen}, number = {3}, issn = {0931-3834}, pages = {67 -- 69}, language = {de} } @article{ThiemeLandenberger, author = {Thieme, Dorothea and Landenberger, M.}, title = {Therapie der akuten tiefen Beinvenenthrombose - eine Literaturrecherche: Verbandtechniken im Vergleich}, series = {Pflegezeitschrift}, volume = {62}, journal = {Pflegezeitschrift}, number = {4}, pages = {206 -- 209}, language = {de} } @article{ThiemeLangerBehrens, author = {Thieme, Dorothea and Langer, G. and Behrens, Johann}, title = {Das Wissen Pflegender zur Kompressionstherapie - Studie zur Therapie der akuten tiefen Beinvenenthrombose}, series = {Pflegezeitschrift}, volume = {62}, journal = {Pflegezeitschrift}, number = {5}, pages = {296 -- 301}, language = {de} } @article{ThiemeLangerBehrens, author = {Thieme, Dorothea and Langer, G. and Behrens, Johann}, title = {Befragung Pflegender zur Kompressionstherapie bei akuter tiefer Beinvenenthrombose}, series = {Pflegezeitschrift}, volume = {63}, journal = {Pflegezeitschrift}, number = {3}, pages = {162 -- 167}, language = {de} } @article{Zuerner, author = {Z{\"u}rner, Christian}, title = {... geheimnisvolle Dinge, die ich in Worten nicht aufsetzen kann : {\"A}sthetik in der religi{\"o}sen Bildung}, series = {Evangelische Aspekte}, volume = {16}, journal = {Evangelische Aspekte}, number = {1}, pages = {27 -- 30}, language = {de} } @article{Zuerner, author = {Z{\"u}rner, Christian}, title = {Auf der Suche nach Identit{\"a}t…}, series = {Arnoldshainer Akzente : Nachrichten aus der Evangelischen Akademie}, journal = {Arnoldshainer Akzente : Nachrichten aus der Evangelischen Akademie}, number = {1}, issn = {0934-7119}, pages = {7}, language = {de} } @article{Schoepf, author = {Sch{\"o}pf, Nicolas}, title = {Mit Kompetenzp{\"a}ssen die Talente ihrer Mitarbeiter kennen und entwickeln}, series = {Personal im Fokus}, journal = {Personal im Fokus}, number = {8}, pages = {30 -- 32}, language = {de} } @article{Schoepf, author = {Sch{\"o}pf, Nicolas}, title = {Grenzkontrollen. Erleichtert die {\"O}ffnung von Bildungswegen kontinuierliches Lernen?}, series = {Berufs- und Wirtschaftsp{\"a}dagogik Online}, journal = {Berufs- und Wirtschaftsp{\"a}dagogik Online}, number = {18}, publisher = {bwp}, issn = {0945-3164}, pages = {20}, abstract = {"Individuelle Bildungsverl{\"a}ufe sind nur zu einem Teil das Ergebnis aktiver pers{\"o}nlicher Planung und Steuerung. Oftmals sind sie das Resultat von Selektion, systemischen Schranken und Abschottungen zwischen Teilen des Bildungssystems. Die Grenzen, die es auf individuellen Bildungspfaden zu {\"u}berschreiten gilt, sind vielf{\"a}ltig: Sie existieren zwischen Jahrgangsklassen, zwischen Grund- und weiterf{\"u}hrenden Schulen bis hin zur Hochschule oder zwischen {\"U}bergangssystem, beruflicher und akademischer Bildung. Gegenw{\"a}rtig verbindet sich insbesondere mit Ans{\"a}tzen der Europ{\"a}isierung der Aus- und Weiterbildung die Hoffnung, Bildungswege zu {\"o}ffnen und damit die M{\"o}glichkeiten lebenslanges Lernen zu erweitern: Die Rede ist dabei von einer Verbesserung der transnationalen Mobilit{\"a}t der Lernenden und der Durchl{\"a}ssigkeit nationaler Bildungssysteme. Es geht dabei also um die Anerkennung von Lernergebnissen, die im Ausland erzielt wurden, und ihre Anrechnung auf deutsche Bildungsg{\"a}nge und um die Anerkennung und Anrechnung von Lernergebnissen zwischen Subsystemen der Bildung in Deutschland. Die Debatte um Durchl{\"a}ssigkeit macht dabei auf mehrere Aspekte aufmerksam: Die Frage, unter welchen Gesichtspunkten Anerkennung diskutiert wird, verweist unter anderem auf das klassische Verh{\"a}ltnis von Qualifizierung und Bildung, von Speziellem und Allgemeinem der Bildung. Damit verkn{\"u}pft stellt sich zudem die Frage, inwieweit auch das Thema Durchl{\"a}ssigkeit eine Rolle f{\"u}r Entwicklungen spielt, die gegenw{\"a}rtig als Neuvermessung des Bildungssystems diskutiert werden." (Autorenreferat; BIBB-Doku).}, language = {de} } @article{Schoepf, author = {Sch{\"o}pf, Nicolas}, title = {Der Qualifikationsrahmen als Weg in mehr Wettbewerb? Potenziale und Herausforderungen europ{\"a}ischer Bildungspolitik f{\"u}r die Erwachsenenbildung}, series = {DIE-Zeitschrift f{\"u}r Erwachsenenbildung}, journal = {DIE-Zeitschrift f{\"u}r Erwachsenenbildung}, number = {2}, publisher = {Bertelsmann}, address = {Bielefeld}, issn = {0945-3164}, doi = {10.3278/DIE1002W045}, pages = {45 -- 48}, abstract = {Der vorliegende Beitrag sondiert Potenziale und Gef{\"a}hrdungen, die f{\"u}r die Erwachsenenbildung aus dem Prozess der Europ{\"a}isierung von Bildungspolitik resultieren. Die zugeh{\"o}rigen strukturellen Wirkmechanismen im Spannungsfeld von Kooperation und Konkurrenz belegt der Text am Beispiel des Europ{\"a}ischen Qualifikationsrahmens (EQR). Mit dem Zweck einer besseren Vergleichbarkeit von Bildungssystemen und Bildungsg{\"a}ngen geht vom EQR unweigerlich der Impuls zu mehr Wettbewerb einher, international wie national. Der Autor ordnet diese Dynamik in die {\"u}bergreifenden bildungspolitischen Prozesse ein, die mit Bolgna, Lissabon und Kopenhagen assoziiert werden.}, language = {de} } @article{Schoepf, author = {Sch{\"o}pf, Nicolas}, title = {Stiefkind Weiterbildung? Anmerkungen zur Diskussion um die Europ{\"a}isierung der Berufsbildung}, series = {Wirtschaft und Berufserziehung : W \& B ; Zeitschrift f{\"u}r Berufsbildung und Bildungspolitik}, volume = {61}, journal = {Wirtschaft und Berufserziehung : W \& B ; Zeitschrift f{\"u}r Berufsbildung und Bildungspolitik}, number = {10}, publisher = {Ziel}, address = {Augsburg}, issn = {0341-339X}, pages = {28 -- 30}, abstract = {ECVET wird gegenw{\"a}rtig haupts{\"a}chlich im Zusammenhang mit der Verbesserung und Flexibilisierung des Ausbildungssystems diskutiert, w{\"a}hrend die berufliche Weiterbildung noch eine untergeordnete Rolle spielt. Der Beitrag beleuchtet Ankn{\"u}pfungspunkte und Handlungsfelder f{\"u}r die berufliche Weiterbildung. Als Handlungsfelder r{\"u}cken Transparenz und Vergleichbarkeit der Weiterbildungsergebnisse und Transparenz und Vergleichbarkeit ausl{\"a}ndischer Qualifikationen in den Blick. ECVET k{\"o}nnte heterogene Prozesse der Weiterbildung angesichts standardisiert beschriebener Lernergebnisse vergleichbar und erzielte Kompetenzen {\"u}ber regionale und tr{\"a}gerbezogene Grenzen hinweg verwertbar machen. (BIBB-Doku).}, language = {de} } @article{Schoepf, author = {Sch{\"o}pf, Nicolas}, title = {Lernergebnisse - Schl{\"u}ssel f{\"u}r die Verst{\"a}ndigung in Europa? Perspektiven f{\"u}r die Erwachsenen- und Weiterbildung}, series = {Bildung f{\"u}r Europa : Journal der Nationalen Agentur beim Bundesinstitut f{\"u}r Berufsbildung}, journal = {Bildung f{\"u}r Europa : Journal der Nationalen Agentur beim Bundesinstitut f{\"u}r Berufsbildung}, number = {15}, publisher = {Nationale Agentur beim Bundesinstitut f{\"u}r Berufsbildung}, issn = {1616-5837}, pages = {33 -- 34}, language = {de} } @article{Schoepf, author = {Sch{\"o}pf, Nicolas}, title = {Die Qual der Wahl. Fragen der Weiterbildungsorganisation und des Einsatzes von eLearning in Unternehmen}, series = {IT-Mittelstand}, journal = {IT-Mittelstand}, number = {12}, publisher = {MEDIENHAUS Verlag GmbH}, pages = {54 -- 58}, language = {de} } @article{Schoepf, author = {Sch{\"o}pf, Nicolas}, title = {Anst{\"o}ße aus Europa}, series = {Personal}, journal = {Personal}, number = {4}, pages = {18 -- 20}, language = {de} } @inproceedings{GriesbergerLeistZellner, author = {Griesberger, Philipp and Leist, Susanne and Zellner, Gregor}, title = {Analysis of techniques for business process improvement}, series = {19th European Conference on Information Systems, ECIS 2011, Helsinki, Finland, June 9-11, 2011}, booktitle = {19th European Conference on Information Systems, ECIS 2011, Helsinki, Finland, June 9-11, 2011}, pages = {12}, abstract = {This paper is about identifying and analyzing techniques that can be used in a business process improvement (BPI) situation. To determine suitable techniques, the term BPI is defined and criteria are derived to analyze the usability of the selected techniques. Over 300 techniques from various improvement methods were reduced to those techniques which can be applied to help improve business processes and, in particular, to support the act of improvement. Identifying these techniques is helpful, because in most cases the act of improvement is a black box that lacks guidelines or structured procedures. In our research we developed an evaluation scheme to analyze the usability of BPI techniques and give hints about how to select a suitable technique for a certain improvement situation.}, language = {en} } @article{HeinrichZellnerLeist, author = {Heinrich, Bernd and Zellner, Gregor and Leist, Susanne}, title = {Service integrators in business networks - The importance of relationship values}, series = {Electronic Markets}, volume = {21}, journal = {Electronic Markets}, number = {4}, publisher = {Springer}, doi = {10.1007/s12525-011-0075-x}, pages = {215 -- 235}, abstract = {To realise the potentials of CRM (customer relationship management), relationship-specific processes need to be designed and implemented in companies. This is all the more important and complicated in business networks where two or more actors collaborate to serve the customers. A good collaboration within business networks is the basis for understanding the customer process and identifying customer needs. But, even in these days of customer orientation, transaction orientation is still a matter of strong interest, and the following questions remain to be answered: What is the difference between relationship-oriented processes and transaction-oriented processes, and how can relationship-oriented processes be designed for a business network? The authors give first answers to both questions by using a systematic, goal-oriented specialisation of generic actions. To give an example, one relationship-oriented process will be designed and specified for a certain customer process in the course of this paper.}, language = {en} } @article{HoegeleLoeschelDobleretal., author = {Hoegele, W. and L{\"o}schel, Rainer and Dobler, Barbara and Hesser, J. and K{\"o}lbl, Oliver and Zygmanski, Piotr}, title = {Stochastic formulation of patient positioning using linac-mounted cone beam imaging with prior knowledge}, series = {Medical physics}, volume = {38}, journal = {Medical physics}, number = {2}, publisher = {American Association of Physicists in Medicine}, doi = {10.1118/1.3532959}, pages = {668 -- 681}, abstract = {PURPOSE In this work, a novel stochastic framework for patient positioning based on linac-mounted CB projections is introduced. Based on this formulation, the most probable shifts and rotations of the patient are estimated, incorporating interfractional deformations of patient anatomy and other uncertainties associated with patient setup. METHODS The target position is assumed to be defined by and is stochastically determined from positions of various features such as anatomical landmarks or markers in CB projections, i.e., radiographs acquired with a CB-CT system. The patient positioning problem of finding the target location from CB projections is posed as an inverse problem with prior knowledge and is solved using a Bayesian maximum a posteriori (MAP) approach. The prior knowledge is three-fold and includes the accuracy of an initial patient setup (such as in-room laser and skin marks), the plasticity of the body (relative shifts between target and features), and the feature detection error in CB projections (which may vary depending on specific detection algorithm and feature type). For this purpose, MAP estimators are derived and a procedure of using them in clinical practice is outlined. Furthermore, a rule of thumb is theoretically derived, relating basic parameters of the prior knowledge (initial setup accuracy, plasticity of the body, and number of features) and the parameters of CB data acquisition (number of projections and accuracy of feature detection) to the expected estimation accuracy. RESULTS MAP estimation can be applied to arbitrary features and detection algorithms. However, to experimentally demonstrate its applicability and to perform the validation of the algorithm, a water-equivalent, deformable phantom with features represented by six 1 mm chrome balls were utilized. These features were detected in the cone beam projections (XVI, Elekta Synergy) by a local threshold method for demonstration purposes only. The accuracy of estimation (strongly varying for different plasticity parameters of the body) agreed with the rule of thumb formula. Moreover, based on this rule of thumb formula, about 20 projections for 6 detectable features seem to be sufficient for a target estimation accuracy of 0.2 cm, even for relatively large feature detection errors with standard deviation of 0.5 cm and spatial displacements of the features with standard deviation of 0.5 cm. CONCLUSIONS The authors have introduced a general MAP-based patient setup algorithm accounting for different sources of uncertainties, which are utilized as the prior knowledge in a transparent way. This new framework can be further utilized for different clinical sites, as well as theoretical developments in the field of patient positioning for radiotherapy.}, language = {en} } @article{HecknerSchneidermeierHastreiteretal., author = {Heckner, Markus and Schneidermeier, Tim and Hastreiter, Isabella and Wolff, Christian}, title = {Der Newbie, der Fortgeschrittene und der Power-User. Warum es nicht reicht, "einfach mal die Nutzer zu fragen"}, series = {i-com}, volume = {11}, journal = {i-com}, number = {3}, publisher = {DeGruyter}, doi = {10.1524/icom.2012.0038}, pages = {47 -- 50}, abstract = {Innerbetriebliche Software entwickelt sich h{\"a}ufig {\"u}ber Jahre hinweg inkrementell weiter, sammelt so Schritt f{\"u}r Schritt Funktionen an und verliert an {\"U}bersichtlichkeit. Soll diese Software hinsichtlich ihrer Gebrauchstauglichkeit optimiert werden, m{\"u}ssen aus Sicht eines externen Usability-Beraters zun{\"a}chst die Dom{\"a}ne des Kunden verstanden und die Arbeitsprozesse analysiert werden. In der Analyse muss insbesondere der Umgang unterschiedlicher Nutzergruppen mit der Software ber{\"u}cksichtigt werden, um fundierte Neuvorschl{\"a}ge in einem Redesign erarbeiten zu k{\"o}nnen. In diesem Erfahrungsbericht beschreiben wir anhand eines konkreten Praxisbeispiels Eigenschaften von Nut-zergruppen und deren Einfluss auf die Analyse, und warum es nicht reicht, die Nutzer „einfach mal zu fragen, wie sie die Software denn finden".}, language = {de} } @phdthesis{Suess, author = {S{\"u}ß, Franz}, title = {The influence of mental stress on the musculoskeletal human back during static posture and trunk motion}, doi = {10.5283/epub.46055}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:355-epub-460554}, pages = {106}, abstract = {The investigation of the influence of mental stress on muscle recruitment of the back and its effect on the intervertebral discs was the main focus of this work. Furthermore, the goal was to develop algorithms to use mental stress as an input parameter in musculoskeletal simulation models. In the first step, a study was designed to investigate the influence of emotional and cognitive stress without kinetic influencing factors during sitting. At the muscular level, emotional stress was found to affect the upper back, while cognitive stress elicited higher muscle activity in the upper and lower back. Using a newly developed algorithm to apply back muscle recruitment changes to static inverse kinematic simulation models, load increases at the discs of up to 189 N on average and up to 907 N at peak were found.Based on the results of the first study, a second dynamic study was designed and conducted. In this case, the focus was on the cognitive stressor and the lower back. Using a dynamometer, subject-specific loads were applied during extension and flexion of the upper back. In contrast to the first study, in the upper back, only the right m. trapezius pars descendens showed a load-induced difference in muscle activity, but the lower back did. To investigate the effects of muscle tone increase in detail, the algorithm developed in the first study was extended to the dynamic case. The use of simulation models allowed the inference of the effects of the purely stress-induced tone increase. For this purpose, the kinetic and muscular effects were isolated and simulated. The study revealed a stress increase of 47\% of the body weight in the L4L5 disc. The final numerical study focused on the general application of muscle activities to inverse kinematic simulation models. This was based on the novel simulation algorithm used in study two and the measured muscle activities. The simulation of the measured muscle activities formed the link between reality and simulation. To simulate the activities, neural networks and gradient boosting regression algorithms were investigated. The latter were found to be better suited to represent the data. However, the data is too small for a detailed statement, especially for loads below 100\%. The results of this work can help to better assess the musculoskeletal effects of psychological stress on the musculoskeletal system and, if necessary, to develop ergonomic prevention strategies. By recognizing stress-related kinematic difference, as well as subsequent prompting of trunk movement, could help prevent long-term effects. When examining any situation, the combination of machine learning and musculoskeletal simulation tools can help examine and minimize the effects of psychological stress.}, language = {en} } @phdthesis{Thumann, author = {Thumann, Philipp}, title = {Lebensdauerbewertung von stoßartig belasteten Werkzeugkomponenten}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:91-diss-20210713-1554721-1-5}, pages = {IV, 143}, abstract = {Die vorliegende Arbeit beinhaltet ein neuartiges Gesamtkonzept zur Betriebsfestigkeitsbewertung von Werkzeugkomponenten unter Ber{\"u}cksichtigung dynamischer Einfl{\"u}sse. Es werden experimentelle Untersuchungen an Proben aus dem Verg{\"u}tungsstahl 42CrMoS4-QT sowie aus den Gusseisen mit Kugelgraphit EN-GJS-600-3 und mit Lamellengraphit EN-GJL-250 durchgef{\"u}hrt. Die Ergebnisse aus den Versuchen dienen zum einen zur allgemeinen Validierung von Betriebsfestigkeitsrechnungen. Zum anderen wird damit die Frequenzabh{\"a}ngigkeit in Bezug auf stoßartige Belastungen untersucht. Neben den validierten Berechnungsmodellen resultiert aus den Versuchungen die Erkenntnis einer ausgepr{\"a}gten Frequenzabh{\"a}ngigkeit, welche in zuk{\"u}nftigen Auslegungsrechnungen ber{\"u}cksichtigt werden muss. Bei Untersuchungen an einem Umform- und Beschneidewerkzeug wird die erarbeitete methodische Vorgehensweise aus den Versuchen angewandt. Es wird eine FE-Simulation eines Gesamtmodells erstellt, welche mit Messungen am Werkzeug validiert wird. Die Untersuchungen am Umform- und Beschneidewerkzeug liefern demnach ein validiertes FE-Simulationsmodell, das neben dem Werkzeug das Pressenmodell und die im Fertigungsprozess zu bearbeitende Platine beinhaltet. Unter Anwendung der Submodelltechnik an einer Einzelkomponente werden geeignete FE-Ergebnisse f{\"u}r eine Betriebsfestigkeitsrechnung generiert. Die Betriebsfestigkeitsrechnung erfolgt nach dem validierten Berechnungsmodell aus den Versuchen. Im Zuge der Analysen am Werkzeug findet das validierte Berechnungsmodell f{\"u}r den Gusswerkstoff EN-GJS-600-3 Anwendung. Die Berechnungsergebnisse korrelieren mit tats{\"a}chlich aufgetretenen Sch{\"a}den an einem Bauteil.}, language = {de} } @phdthesis{Weber, author = {Weber, Sebastian}, title = {Charakterisierung verschiedener Wassereinspritztechnologien f{\"u}r Ottomotoren}, doi = {10.25673/86462}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:ma9:1-1981185920-884176}, pages = {xvii, 151}, abstract = {Die Reduktion von Kraftstoffverbrauch und Schadstoffemission bei gleichzeitiger Verbesserung der Fahrleistung bei kleinerem Hubraum und reduzierter Zylinderzahl, die erh{\"o}hte Performance und die Kompatibilit{\"a}t mit elektrifizierten Komponenten beschreiben die aktuellen Ziele und Herausforderungen der modernen Ottomotorentwicklung. Um alle Herausforderungen zu erf{\"u}llen, muss ein st{\"o}chiometrischer Betrieb sichergestellt werden. Dabei kann es jedoch an der Volllast zur {\"U}berschreitung thermischer Grenzen im Abgaspfad kommen, weswegen die Abgastemperatur ohne Leistungsverluste abgesenkt werden muss. Die Wassereinspritzung kombiniert Downsizing, Leistungssteigerung und die Verbesserung der Schadstoffemissionen wirkungsvoll miteinander und k{\"o}nnte einen Beitrag zur Erreichung der Klimaziele leisten. Um ein optimales Systemlayout zu erarbeiten, sind prozessuale Betrachtungen oft nicht ausreichend. Vielmehr m{\"u}ssen die Ph{\"a}nomene im Brennraum beobachtet werden. Schwerpunktm{\"a}ßig sind dies die Einbringung des Wassers, der Wandkontakt, die Spray- und Wandfilmverdampfung und somit die Wirksamkeit der Abgastemperaturreduktion und die Verbesserung des indizierten Wirkungsgrads. In einem ersten Schritt werden die Thermodynamik bei Wassereinspritzung analysiert und verschiedene Einspritztechnologien miteinander verglichen. Fokussiert wird die Verbrennung, die Ver{\"a}nderung in den gasf{\"o}rmigen und festen Abgasbestandteilen und die mechanische Belastung der Aggregate durch die Verbesserung der Z{\"u}ndwinkel. Die Mischungseinspritzung {\"u}ber den zentralen Hochdruckinjektor vereint den geringsten Wasserverbrauch mit bestm{\"o}glicher Schwerpunktlage, starker Reduktion des Partikelausstoßes und akzeptabler Erh{\"o}hung der mechanischen Belastung und ist damit das favorisierte Konzept. Neben den prozessualen Betrachtungen werden mit einem optisch zug{\"a}nglichen Versuchstr{\"a}ger zwei laseroptische Messtechniken zur Visualisierung fl{\"u}ssigen Wassers und der spektralen Trennung zwischen Wasser und Kraftstoff entwickelt und validiert. Damit werden die verschiedenen Varianten optisch vermessen und die Sensitivit{\"a}t gegen{\"u}ber ver{\"a}nderten Betriebs- und Randbedingungen ermittelt. Die Sammlereinspritzung zeigt die gr{\"o}ßten Tropfen, gefolgt von der Saugrohr- und der Mischungseinspritzung. Auch hat diese den mit Abstand gr{\"o}ßten Wandkontakt und die geringste Verdampfungsrate, ist zus{\"a}tzlich anf{\"a}llig f{\"u}r zyklische Schwankungen. Die Saugrohreinspritzung kennzeichnen kleine Tropfen, ein konzentriertes Einstr{\"o}men durch den Ventilspalt, ein fl{\"a}chiger Wandfilm auf der Kolbenoberseite und die Verbesserung der Tropfenverdampfung durch Turbulenz und die Nutzung von Phasing. Favorit ist abermals die Mischungseinspritzung. Eine hohe Wandfilm- und unmittelbare Sprayverdampfung kennzeichnen das System, wobei eine Erh{\"o}hung des Einspritzdrucks die Verdampfungsrate signifikant verbessert. Außerdem ist die Einspritzdauer am geringsten und die Reproduzierbarkeit am gr{\"o}ßten, jedoch auch der applikative Aufwand. Am favorisierten System werden weitere Analysen durchgef{\"u}hrt, unter anderem zur Ver{\"a}nderung der Bauteiltemperaturen, der Vergleich mit einer Ethanoleinspritzung oder die vielversprechende Kombination in Form einer Wasser-Ethanol-Mischungseinspritzung. Auf Basis der experimentellen Erkenntnisse wird ein CFD-Verfahren vorgestellt, das die Wassereinspritzung abbildet und somit die Virtualisierung in der Produktentwicklung vorantreibt. Neben der methodischen Vorgehensweise wird das Verfahren validiert und am Einzylinder- und Vollmotorbetriebspunkt vorgestellt. Die auftretenden Unterschiede werden analysiert und ausgew{\"a}hlte Parameteranalysen durchgef{\"u}hrt. Mit den Simulationen kann nachvollzogen werden, wie das Wasser die Zylinderlaufbahn benetzt und mit dem Kolben interagiert. Zusammenfassend charakterisiert diese Arbeit die g{\"a}ngigen Wassereinspritzvarianten auf unterschiedlichen Ebenen, gibt Optimierungsempfehlungen f{\"u}r die bestm{\"o}gliche Medienverdampfung und empfiehlt die Mischungseinspritzung als Systemlayout.}, subject = {Kolbenkraftmaschine}, language = {de} } @phdthesis{Weigl, author = {Weigl, Stefan}, title = {Development of a sensor system for human breath acetone analysis based on photoacoustic spectroscopy}, doi = {10.5283/epub.44776}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:355-epub-447768}, pages = {xlii, 282}, abstract = {The breath analysis section of this thesis outlines the potentials but also emphasises the concomitant challenges of human breath analysis. The section further describes the usefulness of a point-of-care (POC) device for breath acetone detection. In addition, it covers various breath analysis related subjects, which can be useful considering further developments of breath analysers. This includes an extensive summary involving the high abundant endogenous as well as the exogenous breath species present in a clinical environment. Subsequently, a detailed discussion about the theoretical aspects of absorption spectra is provided, forming the basis for the spectral interference chapter. Classical absorption spectroscopy (AS) is compared with photoacoustic spectroscopy (PAS) in view of trace gas analysis. Different modulation schemes for signal generation, i.e. amplitude modulation (AM) and wavelength modulation (WM) are part of the comparison, while the advantages and disadvantages of each technique are highlighted. As a result, PAS is considered superior to AS and hence is selected as the method of choice regarding the development of a sensor for breath acetone detection. A detailed mathematical derivation of the photoacoustic signal generation as well as the signal enhancement by means of acoustic resonance amplification is provided. Moreover, several phenomena causing signal attenuation are outlined, including vibrational-translational (VT) relaxation, vibrational-vibrational (VV) energy transfer mechanism, acoustic detuning and photodissociation. Various simulations regarding spectral interferences in the infra-red (IR) and ultraviolet (UV) region are presented, demonstrating the susceptibility towards spectral cross-sensitivities in the IR region, hence, rather suggesting the UV region for acetone detection. However, this simulation can be easily adopted to other target analytes and serves as a basis for multicomponent analysis approaches in the IR region using tuneable light sources. Ultra sensitive acetone detection employing a high power UV LED is presented and a detailed analysis considering the effects of environmental parameters onto the photoacoustic signal, including temperature, pressure, LED duty cycle and flow rate, is provided. In addition, general cross-sensitivities of the photoacoustic signal towards the high abundant species O2, CO2 and H2O have been investigated and discussed. Moreover, several LED and photoacoustic cell (PAC) combinations have been compared in order to evaluate improvement approaches regarding an enhancement of the system's sensitivity. Finally, photoacoustic sensor setups employing an interband cascade laser (ICL) or a quantum cascade laser (QCL) have been studied and compared to various UV setups in view of different key performance parameters, including the limits of detection (LOD) and the normalised noise equivalent absorption (NNEA) coefficients. The juxtaposition of the different approaches once more emphasises the extraordinary sensitivity of photoacoustic spectroscopy. To the best of the author's knowledge, the LODs (3σ) of the UV LED based photoacoustic measurement in typical breath conditions (12.5 ppbV) and the LOD of the QCL measurement (0.79 ppbV) provide two world records. First, regarding photoacoustic acetone detection using an UV LED and second, in view of other published results for photoacoustic acetone detection in general.}, language = {en} } @phdthesis{Weiss, author = {Weiß, Nils}, title = {Security testing in safety-critical networks}, pages = {xiv, 126}, abstract = {The evolution of cars from mechanical systems to rolling computers creates new requirements for safety and security engineering. Nowadays, every vehicle contains a safety-critical real-time communication network to fulfill its function. Especially the increasing connectivity of automotive systems enlarged the attack surface for cyber-attacks. Safety engineering in this area is well understood and studied for decades, though the security engineering of these systems needs further research. This thesis introduces a black-box investigation process to analyze existing auto-motive systems and components and identifies security vulnerabilities in four different ECUs. Combined with a survey of published security research, vehicle-internal networks are identified as an extraordinary threat to the vehicle's safety and security. The outstanding automation capabilities of security tests for these networks are leveraged in the second part of this thesis. In order to create automated tools for automotive networks, a software foundation is necessary. As part of this thesis, a comprehensive open-source software framework for security testing in vehicular networks was developed and published. This aims to support further security research based on open and free software. Novel tools for the automated identification and exploration of attack surfaces in automotive diagnostic protocol implementations are created and evaluated. These tools allow the creation of comparable attack surface metrics through black-box scans of arbitrary ECUs. Automata learning and system state reverse-engineering techniques highly increase the exploration capabilities of the presented tools. The exploration algorithm is tested on thirteen different ECUs from independent OEMs. All gathered results are evaluated and discussed in the final part of this thesis. Finally, open issues and further research based on this contribution are discussed.}, language = {en} } @phdthesis{Wiesent, author = {Wiesent, Lisa}, title = {Numerical analysis of laser powder bed fused stents made of 316L stainless steel considering process-related geometric irregularities}, address = {Regensburg}, doi = {10.5283/epub.53139}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:355-epub-531392}, pages = {XIV, 115, CXV-CXXXI}, abstract = {Re-narrowing of a coronary vessel after stent implantation, known as in-stent restenosis (ISR), is a predominant problem in the treatment of atherosclerosis. ISR is caused, e.g., by vessel wall injury during stent implantation, malpositioning, over- or undersizing of the stent, and associated adverse alteration of natural blood flow. Advances in metal additive manufacturing, particularly in laser powder bed fusion (L-PBF), are enabling the generation of micro-scale L-PBF lattice structures and thus potentially coronary stents. By enabling new or even patient-specific stent designs, L-PBF stents could improve the conformity of the implanted stent and the vessel wall, thus potentially reducing ISR rates in the future. Research in the field of L-PBF stents is still in its early stages. Previous studies have mainly focused on the analysis of stent design requirements and basic functionality of L-BF stents. Studies regarding the determination of the specific mechanical behavior of L-PBF stents but also regarding their numerical analysis are currently not available. Due to their similar topology, L-PBF stents resemble L-PBF lattice structures with a low structural density. Therefore, it is reasonable to transfer the findings in the field of L-PBF lattice structures to L-PBF stents. L-PBF lattice structures exhibit process-related geometric irregularities that (negatively) affect their morphology and their mechanical behavior. Therefore, for an accurate (numerical) evaluation of L-PBF lattice structures and thus of L-PBF stents, their mechanical behavior must be determined first, and the influence of the process-related geometric irregularities must be analyzed or considered within the numerical models. Furthermore, the mechanical and morphological behavior of filigree L-PBF stents can be altered by post-processing steps (surface, heat treatment). However, studies on L-PBF lattice structures are mainly limited to as-built structures. Therefore, the aim of this doctoral thesis is to determine the effects of L-PBF process-related geometric irregularities and different post-processing conditions on the mechanical behavior of L-PBF 316L stents, as well as to develop a numerical methodology for their numerical evaluation. In a first step, a finite element analysis (FEA) for the prediction of stent deformation during crimping and expansion was developed and validated using extensive experimental data from conventionally manufactured stents. These models accurately predicted the expansion behavior of two different stent designs with different expansion behavior, as well as different positioning of the stent on the balloon catheter. In the second step, the mechanical behavior of L-PBF 316L was determined using uniaxial tensile tests on standard flat tensile specimens with variable specimen thickness and orientation angle. For each specimen configuration, as-built and heat treated specimens were considered. In the as-built condition, besides the anisotropic mechanical properties of L-PBF 316L already known from the literature, a significant increase in strength with increasing specimen thickness was observed, which stagnated at a specimen thickness of t > 1.5 mm, thus reaching a saturation value. Heat treatment resulted in homogenization but no recrystallization of the microstructure. Thus, the melt pool boundaries and substructures were dissolved, and residual stresses were reduced, whereas the elongated and oriented grains and thus the anisotropic microstructure were preserved. Accordingly, the specimen thickness- and direction-dependent mechanical properties of L-PBF 316L were still observed after heat treatment. Thus, for a reliable structural mechanical evaluation of L-PBF parts, their mechanical properties must be determined using test specimens that are comparable in size, orientation angle, and post-treatment condition to the later L-PBF part. In a final step, the mechanical behavior of L-PBF stents was determined and the expansion behavior of L-PBF stents under different post-processing conditions was evaluated by FEAs. The generation of L-PBF miniature tensile specimens of comparable cross section to stent struts and their experimental evaluation is challenging and highly error-prone. Therefore, a combined experimental-numerical approach was developed for the inverse determination of the mechanical behavior of L-PBF 316L stents based on experimental testing and FEA of uniaxial compression of L-PBF stents. The stent models were reconstructed from computed tomography (CT) scans of real L-PBF stents. In this way, process-related geometric irregularities were depicted enabling an accurate prediction of the stent structure-property relationship. Thus, the macroscopic mechanical behavior of L-PBF 316L stents could be determined for the first time and subsequently described numerically by a material model. Morphological analysis of the L-PBF stents further revealed significant discrepancies between the actual L-PBF stents and its computed aided design (CAD) model due to process-related geometric irregularities (surface roughness, strut waviness, enlarged and inhomogeneous strut diameters, internal defects). Numerical expansion analysis of the L-PBF stent models showed that L-PBF stents can exhibit comparable expansion behavior to conventional stents only after surface and heat treatment. However, subsequent analysis of deformation and stress states showed that L-PBF stents, both in the as-built condition and after surface and heat treatment, may exhibit critical local stress/strain concentrations, especially in the areas of pronounced geometric irregularities. Improvements in the L-PBF process, post-processing steps, and stent design are therefore essential to minimize process-related geometric irregularities and thus their strength-reducing effects, ultimately ensuring the structural safety of L-PBF stents. One possible improvement approach is to manufacture the stents on special µ-L-PBF systems that have explicitly been optimized to produce filigree structures. In this way, a higher geometric accuracy and low surface roughness could already be achieved in the as-built condition of L-PBF stents, and the subsequent required surface treatment could be reduced to a minimum. Furthermore, the fatigue strength, the damage behavior, the interaction of the stent with the blood vessel as well as the biocompatibility of L-PBF 316L stents should be investigated. To effectively use numerical models for the development of L-PBF stents, the potential of synthetic L-PBF stent models should also be investigated. The synthetic stent models represent a statistics-based modification of the original stent CAD model (e.g., local variations of strut cross section along strut length). In this way, the effects of L-PBF process-related geometric irregularities could be represented statistically and thus without explicit reconstruction from CT scans. The development of L-PBF stents is a very complex interdisciplinary task in the fields of manufacturing technology, material science, design development and numerical simulation. To establish L-PBF as a reliable alternative to conventional stent fabrication, further research in this area is essential. By providing a method to determine the mechanical properties of L-PBF stents as well as their numerical analysis, this doctoral thesis could contribute to the further development of L-PBF 316L stents, as well as define necessary research aspects for further work.}, language = {en} } @phdthesis{Wulf, author = {Wulf, Frederik}, title = {Essays on cloud computing adoption, post-adoption, and security}, pages = {166}, language = {en} } @phdthesis{Grauvogl, author = {Grauvogl, Dominik}, title = {Multiphysikalische Auslegung einer fremderregten Synchronmaschine mit magnetischer Asymmetrie f{\"u}r einen Hochvolt-Achsantrieb}, editor = {Gerling, Dieter}, publisher = {Shaker Verlag}, address = {D{\"u}ren}, isbn = {9783844085532}, pages = {260}, abstract = {In der vorliegenden Arbeit wird eine fremderregte Synchronmaschine als Achsantrieb f{\"u}r ein Elektrofahrzeug entwickelt. Als Grundlage hierf{\"u}r dient ein bereits vorhandener Stator einer permanenterregten Synchronmaschine. Durch die Wiederverwendung des Stators ist eine maschinentypunabh{\"a}ngige Baukastenerweiterung in Form eines magnetfreien Rotors gegeben, wodurch die {\"o}konomischen und {\"o}kologischen Nachteile der Permanentmagnete ausgeschlossen sind. Bei der Auslegung des Rotors wird von Beginn an ein multiphysikalischer Entwicklungsansatz gew{\"a}hlt, mit dem der praxistaugliche Einsatz f{\"u}r den modularen Baukasten sichergestellt ist. Dabei ist die elektromagnetische Auslegung iterativ auf die mechanische Blechpaketfestigkeit, das thermische Verhalten und die magnetischen Ger{\"a}usche abgestimmt. In Kombination mit den gesetzten Restriktionen ergibt sich ein neuartiges asymmetrisches Polschuhdesign mit dem es m{\"o}glich ist, das geforderte Drehmoment mit gen{\"u}gend kleiner Welligkeit ohne eine Rotorschr{\"a}gung zu erreichen. Die Simulationsergebnisse sind durch die Vermessung eines aufgebauten Prototyps validiert und best{\"a}tigt. Ein abschließender Simulationsvergleich mit der baugleichen permanenterregten Synchronmaschine zeigt, dass die fremderregte Synchronmaschine hinsichtlich Performance, Wirkungsgrad und Ger{\"a}uschverhalten eine konkurrenzf{\"a}hige Alternative dazu ist.}, language = {en} } @phdthesis{Munninger, author = {Munninger, Maximilian}, title = {Betrachtung der inh{\"a}renten Stochastizit{\"a}t durch das Scheduling in Verbindung mit der mehrstufigen Losbildung in einem hierarchischen Planungskonzept}, volume = {2022}, edition = {1. Auflage}, publisher = {Cuvillier Verlag}, address = {G{\"o}ttingen}, isbn = {9783736975958}, pages = {142}, abstract = {In der Dissertationsschrift „Betrachtung der inh{\"a}renten Stochastizit{\"a}t durch das Scheduling in Verbindung mit der mehrstufigen Losbildung in einem hierarchischen Planungskonzept" werden mehrere Modellformulierungen f{\"u}r die L{\"o}sung von mehrstufigen kapazitierten Losgr{\"o}ßenproblemen erarbeitet. Bei der Losgr{\"o}ßenplanung mit Mikroperiodenmlodelen entstehen durch die {\"u}blicherweise integrierte Reihenfolgeplanung keine Versp{\"a}tungen durch Wartezeiten. Jedoch sind die Rechenzeiten f{\"u}r optimale L{\"o}sungen in praxisrelevanten Problemgr{\"o}ßen nahezu unbeherrschbar. Bei einer L{\"o}sung mit Makroperiodenmodellen und einer nachfolgenden Reihenfolgeplanung mit Priorit{\"a}tsregeln entstehen hingegen durch die unzureichenden Kapazit{\"a}tsberechnungen immer wieder unvorhergesehene Wartezeiten. Deshalb werden in der Arbeit drei Modifikationen f{\"u}r das Makroperiodenmodell MLCLSP vorgeschlagen, mit denen diese Wartezeiten gesch{\"a}tzt werden k{\"o}nnen. Im ersten Ansatz werden Kapazit{\"a}tskorrekturfaktoren eingef{\"u}hrt und deren Werte simulativ ermittelt, womit das Problem der reihenfolgebedingten Wartezeiten teilweise behoben werden kann. In einem zweiten Modellvorschlag werden diese Kapazit{\"a}tskorrekturfaktoren mit einer Analogie aus der Warteschlangetheorie gesch{\"a}tzt. Ein drittes Modell wird vorgeschlagen, in dem ein Parameter eingef{\"u}hrt wird mit dem die Robustheit gegen{\"u}ber der inh{\"a}renten Stochastizit{\"a}t zwischen den Losgr{\"o}ßen- und Scheduling-Problemen gesteuert werden kann.}, language = {de} } @phdthesis{Schwanzer, author = {Schwanzer, Peter}, title = {Experimentelle Untersuchungen zur On-Board {\"U}berwachung von Partikelfiltern f{\"u}r den Einsatz an direkteinspritzenden Benzinmotoren}, publisher = {Verlag Dr. Hut}, address = {M{\"u}nchen}, isbn = {978-3-8439-5101-2}, pages = {194}, abstract = {This thesis deals with the development of a methodology for an improved on-board diagnosis of particulate filters in vehicles with gasoline direct injection (GDI) technology with regard to future emission legislations. In order to comply with statutory particle number limits, particulate filters are used in the exhaust gas aftertreatment for GDI-engines. The currently applied method for diagnostic purposes, a differential pressure sensor, will not be suitable for future legislations. Therefore, an on-board strategy with real-time ability shall be developed. To achieve this, the application of novel sensor concepts has been investigated, namely electrostatic soot sensors (ePM sensor) and radio frequency antennas (RF sensor). Due to the results of the ePM-sensors, no methodology for an on-board diagnosis based on an ePM sensor concept was made. The RF sensor showed varying sensitivities for different soot and different quantities of volatile components in the filter element. The analysis of the oxidation processes showed that the regeneration of the filter element is detected by the RF sensor. Furthermore, the stored amount of ash could be captured. Due to these findings, a concept for an improved on-board diagnosis strategy by means of an RF sensor concept was developed. In the course of the work it turned out that a combined sensor concept consisting of a differential pressure sensor and a RF sensor is most suitable. In a validation process, this sensor concept showed sufficient results concerning the detection capability of soot and ash loads as well as of the degree of damage of particulate filters. Especially for small amounts of ash, this sensor concept showed specific advantage. Also, the determination of the current amount of soot in the filter element proved to be suitable. Regarding the detection of damages, the sensor concept convinces through a higher sensitivity.}, language = {de} } @phdthesis{Muehlbauer, author = {M{\"u}hlbauer, Christian}, title = {Entwicklung einer Methodik zur Bewertung und Optimierung des vibroakustischen Verhaltens von Kraftstoffeinspritzsystemen}, doi = {10.25673/109576}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:ma9:1-1981185920-1115312}, pages = {IX, 119}, abstract = {Die vorliegende Dissertation befasst sich mit der akustischen Analyse von Kraftstoffein-spritzsystemen und deren NVH-Optimierung mithilfe ansteuerungstechnischer Maßnahmen. Da sich der K{\"o}rper- und Luftschall beim Betrieb des Verbrennungsmotors mit anderen, nicht untersuchungsrelevanten Ger{\"a}uschkomponenten {\"u}berlagert, ist im Vollmotorbetrieb eine diffe-renzierte komponentenbasierte Ger{\"a}uschmessung nicht m{\"o}glich. Deshalb wurde ein NVH-Sys-tempr{\"u}fstand entwickelt, der eine isolierte akustische Vermessung von Einspritzsystemen im seriennahen Systemverbund erm{\"o}glicht. Die Betriebsparameter des Einspritzsystems wurden an einem Vollmotor in einem leerlaufna-hen Motorbetriebspunkt erfasst und mithilfe eines speziellen Entwicklungssteuerger{\"a}ts auf den NVH-Systempr{\"u}fstand transferiert. Ausgehend von dem definierten Referenzbetriebspunkt wurden sowohl die Randbedingungen als auch die Ansteuerstrategie variiert und deren Einfluss auf das akustische Verhalten analysiert. Dabei zeigten prim{\"a}r der Raildruck und die Anzahl der Einspritzungen einen ausgepr{\"a}gten Einfluss auf die betrachteten (psycho-)akustischen Parame-ter Schalldruckpegel, Lautheit, Sch{\"a}rfe und Impulshaltigkeit. Zur akustischen Optimierung der mechatronischen Komponenten wurden zum einen der An-steuerstrom reduziert und zum anderen ein Bremsimpuls am Ende der Ansteuerung implemen-tiert. Dadurch konnten die mechanischen Prellereignisse deutlich reduziert werden. Mithilfe eines Einspritzratenmessger{\"a}ts wurde allerdings nachgewiesen, dass sich die Optimierungs-maßnahmen insbesondere auf die Streuung der eingespritzten Kraftstoffmasse negativ auswir-ken und damit ein Zielkonflikt aus Ger{\"a}uschqualit{\"a}t und Prim{\"a}rfunktionen entsteht. Als signi-fikanter Kipppunkt wurde bei den Injektoren der {\"U}bergang vom linearen Vollhub-Betrieb zum ballistischen Teilhub-Betrieb identifiziert. Aus diesem Grund wurde die elektrische Ansteue-rung unter der Voraussetzung des Injektor-Vollhub-Betriebs optimiert. Bei der Beurteilung des Einflusses der NVH-optimierten Ansteuerprofile auf die Robustheit der mechatronischen Komponenten wirkten sich eine niedrige Versorgungsspannung sowie eine kurze Ansteuerdauer der Injektoren besonders negativ auf die Streuung der eingespritzten Kraftstoffmasse aus. Vor allem in Verbindung mit der stromreduzierten Ansteuerung wurden die Injektoren nicht mehr zuverl{\"a}ssig und reproduzierbar im Voll-Hub ge{\"o}ffnet. Weiterhin wur-den durch die Bremspuls-Applikation injektorspezifische Abweichungen im Schließverhalten weiter verst{\"a}rkt und erh{\"o}hten damit auch die Abweichungen der mittleren eingespritzten Kraft-stoffmasse zwischen den untersuchten Injektor-Exemplaren. Abschließend wurde die {\"U}bertragbarkeit des Systemverhaltens ermittelt, indem die Optimie-rungsmaßnahmen auf einen weiteren Versuchstr{\"a}ger ausgeweitet wurden. Dabei zeigte sich, dass die Maßnahmen zwar grunds{\"a}tzlich {\"u}bertragbar waren, aber die Parametrierung bez{\"u}glich Ansteuerstromreduzierung und Bremspuls-Applikation zum Teil stark angepasst werden mussten.}, language = {de} } @phdthesis{Baumann2023, author = {Baumann, Martina}, title = {Health Technology Assessment und ethische Aspekte der Prothesenversorgung}, doi = {10.5445/IR/1000170547}, pages = {viii, 270, XLIV}, year = {2023}, abstract = {Innovative Hand- und Beinprothesen haben das Potenzial, die Gesundheit und Lebensqualit{\"a}t von Menschen mit Gliedmaßenamputationen und Dysmelien zu verbessern. Aus einer Behindertenrechtsperspektive haben Menschen ein Recht auf eine Versorgung mit solchen Hilfsmitteln, die ihnen mehr gesellschaftliche Inklusion erm{\"o}glichen. Gleichzeitig k{\"o}nnen neue Prothesentechnologien Gesundheitssysteme aufgrund ihrer hohen Kosten vor Herausforderungen in Bezug auf die gerechte Ressourcenallokation stellen. Auch die zunehmende Verschmelzung von Prothesen mit menschlichen K{\"o}rpern wirft ethische Fragen nach Autonomie und Sicherheit auf. Das Health Technology Assessment (HTA) ist ein wissenschaftlicher Ansatz zur Effizienzsteigerung und gerechten Rationierung in Gesundheitswesen. HTA soll Entscheidungen zur Erstattungsf{\"a}higkeit von Gesundheitstechnologien unterst{\"u}tzen, indem es deren Kosten und Nutzen systematisch untersucht - aber auch ethische, rechtliche und soziale Aspekte ihres Einsatzes beleuchtet. Diese Arbeit gibt einen {\"U}berblick {\"u}ber den Stand des HTA zu Prothesen auf Basis einer Recherche zu HTA-Berichten und Einsch{\"a}tzungen von Stakeholder*innen des deutschen Gesundheitswesens. Ethische Aspekte der Prothesentechnologie und -versorgung werden auf Basis eines Literaturreviews und einer Befragung von Prothesentr{\"a}ger*innen beleuchtet. Dieser Teil der Arbeit untersucht auch, inwiefern solch eine Kombination aus literaturbasiertem und empirischem Ansatz („empirische Ethik") einen Mehrwert f{\"u}r Ethik im HTA bietet. In einem Fokus auf Gerechtigkeit wird untersucht, welche H{\"u}rden von Prothesennutzer*innen und Stakeholder*innen beim Zugang zu Prothesen im deutschen Gesundheitssystem wahrgenommen werden und inwiefern diese H{\"u}rden zu ungerechtem Zugang f{\"u}hren k{\"o}nnen. Es werden dann basierend auf den empirisch identifizierten Defiziten in der Versorgungspraxis und Norman Daniels Ansatz f{\"u}r Gesundheitsgerechtigkeit Empfehlungen f{\"u}r eine gerechtere und bessere Prothesenversorgung vorgestellt. Die Arbeit liefert somit Beitr{\"a}ge zur methodischen Diskussion um Ethik im Health Technology Assessment und zur bislang in Deutschland eher z{\"o}gerlich gef{\"u}hrten Diskussion, wie mit Ressourcenknappheit im Gesundheitswesen umgegangen werden sollte.}, language = {de} } @phdthesis{Jonker2023, author = {Jonker, Dirk}, title = {Advanced nanofabrication techniques for electron emission devices}, isbn = {978-90-365-5632-3}, doi = {10.3990/1.9789036556323}, pages = {362}, year = {2023}, abstract = {The goal of this thesis is to develop an electron injection source based on a cold field emission cathode that ultimately functions as an alternative electron source used during the Birch reduction process. The experimental configuration to conduct an alternative Birch reduction involves the combination of various physical domains, including solid-state physics, physics of interfaces, electrochemistry, and fluid dynamics. The body of this thesis discusses the fabrication and characterization of a silicon nanocone array. It also presents a self-aligned method to incorporate an electronic gate structure that may function as an extractor grid. The emission behavior and transport properties of the silicon nanocones are assessed by scanning tunneling microscopy by performing measurements on flat silicon and silicon nanocone surfaces containing different dopant types and doping concentrations. Furthermore, additional experimental work is conducted to replace a thermally grown silicon dioxide layer with platinum silicide and characterize the electrical properties by means of scanning tunneling microscopy. Lastly, the thesis discusses the fabrication of two plasmonic structures and evaluates the plasmonic modes, surface enhancement, and Raman activity.}, language = {en} } @phdthesis{Kratzer, author = {Kratzer, Simon}, title = {The Fractional CIO as a new form of IT management for SMEs : essays on current issues and new developments in IT executive management}, url = {http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa2-894186}, pages = {27, 46, 85-87, 119-120, 131, 148, 172-173}, abstract = {For decades, the importance of information technology (IT) for organizations has continuously increased. To ensure effective IT management and operations, to enable the business, and to stay competitive, many large organizations appoint a Chief Information Officer (CIO) as their highest-ranked IT executive (Preston et al., 2008). While many small to medium-sized enterprises (SMEs) face similar challenges concerning IT, they often lack the resources to employ a full-time IT executive (Bhagwat \& Sharma, 2007; Cragg et al., 2013). However, Kamariotou and Kitsios (2022) find that strategic planning and alignment with IT are important determinants for increasing an SME's business value. An increasing number of SMEs started to employ CIOs part-time to avoid the risk of not staying competitive and losing business value (Moise, 2021; Pratt, 2022). Such so-called "Fractional CIOs" are often highly experienced and skilled individuals working for multiple SMEs simultaneously (Kratzer et al., 2022). By contracting a Fractional CIO, SMEs benefit in various ways. First, they get an experienced IT leader at a fraction of the cost. Second, they remain flexible concerning billable hours and the time horizon of the engagement. Third, they are receiving an outside-in perspective and might profit from the Fractional CIO's experience gained from simultaneous engagements. Even though the Fractional CIO role benefits SMEs, adoption and awareness are still low. Further, substantial research on the novel role is missing. This dissertation aims to establish a new stream in CIO research that explores the role of the Fractional CIO. Our comprehensive literature review of the CIO research field provides the basis for this research (Kratzer et al., 2023b). As we explore this novel phenomenon, we are also interested in how to best report research findings. We, therefore, aim to conceptualize techniques to convey novel phenomena in information systems (IS) research in an illustrative way. Hence, we posed the following overarching research questions: RQ1: How can novel phenomena be communicated in an illustrative yet rigorous way in research papers? RQ2: What is the state-of-the-art in the CIO research field, and what are further avenues for research? RQ3: What concepts provide SMEs with the experienced IT executive management they need? RQ4: What makes Fractional CIO engagements successful? RQ5: How does the role of the Fractional CIO take shape in practice in the German market? These overarching research questions are answered through six consecutive publications. 1) 'Literary Sketches in Information Systems Research: Conceptualization and Guidance for Using Vignettes as a Narrative Form' This paper is conceptual and has a methodological focus on the use of vignettes. The paper contributes to the usage of vignettes as a narrative form in academic research, providing a taxonomy that structures vignettes and identifies three archetypes. By conceptualizing vignettes through a taxonomy and archetypes, we create transparency for the usage of vignettes, encourage the use of vignettes, and provide recommendations how to use them more rigorously. Long term, this might contribute to a better exchange between academia and practice through better comprehensibility of academic papers. 2) 'Four Decades of Chief Information Officer Research: A Literature Review and Research Agenda Based on Main Path Analysis' In this paper, we conducted a bibliographic literature review using main path analysis, which helped to objectively identify existing topics based on their importance. We also illustrated the knowledge flow in CIO research by identifying major and emerging research streams and analyzing their evolution over time. Additionally, we aggregated central papers in CIO research and developed a research agenda to provide guidance for future research. Overall, this paper helps to advance the understanding of the CIO research field and provides insights for researchers and practitioners. 3) 'The Fractional CIO in SMEs: Conceptualization and Research Agenda' With this paper, we were the first to conceptualize the role of the Fractional CIO and to develop a research agenda for this novel research field. The results from this paper contribute to research and practice in several ways. First, we are the first authors to conceptualize the role of the Fractional CIO, derive a definition, compare it to existing CIO role research, and derive four engagement types. Second, we develop a research agenda to guide future research in the new Fractional CIO research field. Third, we contribute to practice by promoting the role's awareness among potential Fractional CIOs and organizations. Fourth, we show that Fractional CIO services are versatile and can benefit organizations of different sizes and maturity levels, and there are diverse possibilities for evolution. 4) 'What Makes Fractional CIO Engagements in SMEs Successful? - A Research Framework' In this paper, we developed a research framework for Fractional CIO engagement success. It makes contributions to research and practice. First, we propose a research framework for Fractional CIO engagement success and, therefore, develop a common ground for future research. Second, we provide practical advice for Fractional CIOs and SMEs regarding factors for engagement success. Third, we raise awareness about the Fractional CIO role that may benefit many SMEs around the world. 5) 'Factors for Fractional CIO Engagement Success' In this paper, we used Q-methodology to empirically evaluate the relative importance of factors influencing Fractional CIO engagement success and to identify different viewpoints on engagement success. Our paper makes several contributions to research and practice. First, our paper is the first to identify and evaluate the importance of factors for Fractional CIO engagement success. Therefore, it serves as a basis for further research in the new Fractional CIO research field. Second, we find that upper echelon theory (Hambrick \& Mason, 1984) can be applied to executives independent of their contractual relationship in cases of comparable responsibilities. Third, by thoroughly applying Q-methodology, we showcase an exploratory tool for identifying opinions and preferences of participants and clustering them accordingly. This approach provides guidance for other IS scholars to apply it. Fourth, we develop preliminary archetypes of Fractional CIOs and, based on that, provide tentative advice for Fractional CIOs and organizations that hire them. These preliminary archetypes enabled us to identify further theoretical explanations of this phenomenon. In addition to transaction cost theory, agency theory, and upper echelon perspective, we found that stewardship theory and dynamic capabilities explain additional characteristics of Full-ownership CIOs and Change Agents. 6) 'Mehr als Vollzeit: Fractional CIOs in KMUs' This paper summarizes the results of our previous studies regarding the Fractional CIO role in German language and conducts semi-structured interviews with three Fractional CIOs from Germany to complement it with a perspective on the German market. Overall, we find that the Fractional CIO role in the German market is performed similarly to the international market. The interviewed German Fractional CIOs/CTOs could not clearly identify any hurdles that might explain the low adoption of the role. However, all three German Fractional CIOs agree that German SMEs would strongly benefit from Fractional CIOs. (References to be found in the full text)}, language = {en} } @phdthesis{Lalo, author = {Lalo, Erjola}, title = {Deployment designs for multi-core-real time systems}, edition = {1. Auflage}, publisher = {Universit{\"a}tsverlag Regensburg}, address = {Regensburg}, isbn = {978-3-86845-181-8}, doi = {10.21268/20240712-0}, url = {http://nbn-resolving.de/urn:nbn:de:gbv:104-20240712-00000-7}, pages = {iii, 371}, abstract = {In modern embedded automotive systems, multi-core processors are used to provide higher execution performance and more computing capacity. However, they influence the way these systems are designed. Each change of the platform and application software results in an effort required to ensure and validate the functional correctness and timing requirements of these systems in a multi-core platform. For this reason, the use of the Logical Execution Time (LET) paradigm is advantageous for multi-core systems, as it satisfies these requirements by providing time and dataflow determinism, thereby reducing the development cycle and the impact of the platform in the design of such systems. To integrate LET into these systems, special mechanisms are required to satisfy its semantics. Therefore, this work focuses on buffering and scheduling techniques for resource efficient integration of LET in automotive systems. A buffering mechanism and an automatic schedule synthesis are proposed to guarantee functional correctness, timing requirements, and LET semantics and to reduce the increased demands of LET for memory and processor resources. A static and global buffering protocol is proposed, which compared to lock-based protocols has plausible memory needs and zero-communication overheads at the boundaries of LET intervals. The automatic schedule synthesis considers the Operating System (OS) overheads such that scheduling is optimized with respect to context-switching overheads caused by preemption. Buffering implements most of the LET semantics, but it provides no guarantee that tasks execute within their LET intervals. If scheduling is not designed to ensure that all tasks execute within their LET intervals, then functional correctness and LET semantics are violated. The manual design of a feasible schedule that satisfies the semantics and additional requirements of the application is inefficient and requires a significant amount of effort. Therefore, an automatic schedule generation approach for the Fixed-Priority Scheduling (FPS) and Time-Triggered Scheduling (TTS) is proposed. FPS is the widely used mechanism in the automotive domain because of its flexibility to handle dynamic changes of highly event-driven applications. Recently, TTS has attracted considerable attention in this domain to increase deterministic execution of tasks and efficient planning of processor resources. Therefore, schedule synthesis of FPS and TTS is provided to identify the efficiency, practicality, and resource optimization abilities of each approach for LET systems. To show the practicality of LET for industrial automotive systems, its integration into the software architecture of the classic platform of AUTomotive Open System Architecture (AUTOSAR) is described and a case study is conducted using a real world system.}, language = {en} } @phdthesis{Lindner, author = {Lindner, Matthias}, title = {Miniaturisierte dielektrische Barrierenentladungen und ihre Anwendung f{\"u}r das Anti- bzw. De-Icing von aerodynamischen Oberfl{\"a}chen}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:384-opus4-1118933}, pages = {XI, 155}, abstract = {Das grundlegende physikalische Verst{\"a}ndnis und die kontinuierliche Weiterentwicklung von dielektrischen Oberfl{\"a}chenbarrierenentladungen (SDBDs) sowie der damit erbundenen elektrischen Diagnostik, sind f{\"u}r eine Vielzahl von Niedertemperaturplasmaanwendungen von entscheidender Bedeutung. In Bezug auf die Anwendung dieser Plasmatechnologie in der Luftfahrt liegt neben der bereits umfassend erforschten aktiven Str{\"o}mungskontrolle zunehmend der Schwerpunkt auf der Vermeidung von Eisablagerungen auf aerodynamischen Komponenten. Die Bildung von Eis auf Oberfl{\"a}chen wie zum Beispiel den Tragfl{\"a}chen kann unter extremen Wetterbedingungen erhebliche Leistungsdefizite hervorrufen und zu ernsthaften Sicherheitsrisiken f{\"u}hren. In Anbetracht der signifikanten Vorteile gegen{\"u}ber traditionellen Enteisungsmethoden steht die Erforschung von SDBDs im Mittelpunkt des anwendungsorientierten Abschnitts dieser Arbeit. Vorliegende Arbeit untergliedert sich in einen grundlegenden und einen anwendungsbezogenen Teil. Darin werden sowohl die physikalischen Eigenschaften und Prozesse von SDBDs analysiert als auch ihre potenziellen Anwendungen in Bezug auf Flugsicherheit und Effizienz untersucht. Die wissenschaftliche Forschung hat in der Vergangenheit erhebliche Anstrengungen unternommen, um ein umfassendes Verst{\"a}ndnis der physikalischen Vorg{\"a}nge, die im Zusammenhang mit SDBDs stehen, zu erarbeiten. Insbesondere die pr{\"a}zise Bestimmung der r{\"a}umlichen Ausdehnung der Entladung entlang der dielektrischen Oberfl{\"a}che - die {\"u}blicherweise in direkter Proportionalit{\"a}t zur Amplitude der angelegten Spannung steht - ist hierbei eine herausfordernde Aufgabe. Diese umfangreichen Studien sind essenziell, um die Entladungseigenschaften und die grundlegenden physikalischen Prozesse zu verstehen, was erhebliche Anwendungspotenziale er{\"o}ffnet. Parallel zu diesen grundlegenden Studien hat sich auch der praktische Einsatz von SDBDs zur Verhinderung der Eisbildung auf aerodynamischen Bauteilen bedeutend weiterentwickelt. Untersuchungen legen nahe, dass L{\"o}sungen auf Basis von SDBDs im Vergleich zu konventionellen Enteisungsmethoden, wie beispielsweise chemischen Enteisungsmitteln oder thermischen Systemen, ein h{\"o}heres Effizienz- und Wirkungspotential besitzen k{\"o}nnten. Allerdings wurden bisherige Entwicklungen von SDBDs haupts{\"a}chlich auf Basis der Leiterplattentechnologie realisiert, was bestimmte Begrenzungen in Bezug auf ihre Anwendbarkeit f{\"u}r Anti-Icing- Technologie mit sich bringt. Im ersten Teil dieser Arbeit wurde die sequentielle Ausbreitung der SDBD-Entladung entlang der dielektrischen Al2O3-Oberfl{\"a}che systematisch analysiert. Die durchgef{\"u}hrten experimentellen Untersuchungen zeigten, dass die Entladungen unmittelbar nach dem Erreichen der Z{\"u}ndspannung einen fest definierten Bereich belegen, der bis zum Erreichen einer kritischen Spannungsamplitude VL stabil bleibt. Anzumerken ist auch, dass das Ausbleiben der Plasmaausbreitung innerhalb dieses Spannungsbereichs zu einer linearen Korrelation zwischen der Entladungsleistung und der angelegten Spannungsamplitude f{\"u}hrt. Diese tiefergehenden Einblicke in die Dynamik der Entladung k{\"o}nnen dazu beitragen, den Einsatz von SDBDs in diversen Anwendungsbereichen effizienter zu gestalten. Im zweiten Teil der Arbeit steht die Entwicklung und Implementierung eines innovativen Ansatzes zur Realisierung von SDBDs im Vordergrund, der auf der Nutzung von D{\"u}nnschichtsubstra-Vten und mikroelektromechanischen Systemen (MEMS) basiert. Die Verwendung dieser Technologie erlaubt einen pr{\"a}ziseren Design- und Fertigungsprozess von Elektrodenstrukturen, was sich positiv auf die Effizienz der Enteisung auswirken kann. Zur Beurteilung des Anti-Icing-Potenzials der entwickelten MEMS-SDBDs wurde ein direkter Vergleich mit konventionellen PCB-SDBDs durchgef{\"u}hrt. Die Ergebnisse legen nahe, dass die 35 μm dicken Elektroden der PCB-SDBDs eine Oberfl{\"a}chenvereisung f{\"o}rdern, die vorrangig durch die Elektrodenkanten induziert wird. Im Gegensatz dazu wurde dieser Effekt bei den deutlich d{\"u}nneren, lediglich 0.3 μm dicken, mittels MEMS gefertigten Elektroden nicht festgestellt. Diese Beobachtungen deuten darauf hin, dass SDBDs, die mit MEMS-Technologien gefertigt wurden, einen signifikanten Vorteil in Anti-Icing-Anwendungen aufweisen k{\"o}nnten und stellen somit einen wesentlichen Fortschritt in der Forschung und Anwendung von SDBDs dar. Die in dieser Arbeit vorgelegten Forschungsergebnisse und innovativen Methoden liefern zahlreiche neue Erkenntnisse, die das Potential besitzen, sowohl das Verst{\"a}ndnis als auch die Anwendung von SDBDs wesentlich zu erweitern. So best{\"a}tigen die Langzeitbelichtungsaufnahmen das neu entdeckte Ph{\"a}nomen einer sequenziellen Ausbreitung des Entladungsplasmas, das bei SDBDs mit dickeren Dielektrika st{\"a}rker ausgepr{\"a}gt ist. Eine neu entwickelte Methodik erm{\"o}glicht die Anwendung der Ladungs-Spannungs-Charakteristik von SDBDs, um essenzielle Parameter f{\"u}r ein vereinfachtes Ersatzschaltbild abzuleiten. Dar{\"u}ber hinaus wurde eine bemerkenswerte numerische {\"U}bereinstimmung zwischen der Ladungs-Spannungs-Charakteristik f{\"u}r den positiven Halbzyklus der Entladung und der aus den optischen Aufnahmen abgeleiteten spannungsabh{\"a}ngigen Reaktorkapazit{\"a}t festgestellt. Diese Erkenntnisse {\"o}ffnen neueWege f{\"u}r die Optimierung und Anwendung von SDBDs in verschiedenen technischen Bereichen. Weiterhin identifizierte die durchgef{\"u}hrte Erosionsstudie Titan als optimal geeignetes Material f{\"u}r MEMS-Elektroden aufgrund seiner hohen Korrosionsbest{\"a}ndigkeit und ausgezeichneten elektrischen Leitf{\"a}higkeit. Es wurden auch Potentiale zur Optimierung von MEMS-SDBDs durch die Auswahl geeigneter dielektrischer Materialien und geeigneter SDBD-Geometrien aufgezeigt. Eine solche Optimierung k{\"o}nnte die Enteisungseffizienz weiter verbessern, indem beispielsweise die dielektrischen Eigenschaften an die spezifischen Anwendungsanforderungen angepasst werden. Innovative Designkonzepte, wie eine gezielte Anordnung der Elektroden oder die Integration von Sensoren zur {\"U}berwachung des Enteisungsprozesses, k{\"o}nnten ebenfalls zur Leistungsf{\"a}higkeit und Zuverl{\"a}ssigkeit von MEMS-SDBDs beitragen. Ein weiterer bedeutender Aspekt ist die Anwendung von Piezotransformatoren zur Generierung der ben{\"o}tigten Hochspannung f{\"u}r SDBD-Systeme. Dieser innovative Ansatz k{\"o}nnte die Effizienz des auf SDBD-Technologie basierenden Enteisungsverfahrens optimieren und somit zur Verbesserung der Leistungsf{\"a}higkeit und Sicherheit von Flugzeugen unter extremen Wetterbedingungen beitragen. Das Forschungsfeld bietet viel Raum f{\"u}r zuk{\"u}nftige Studien, was die Bedeutung und Zukunftsrelevanz der in dieser Arbeit gewonnenen Ergebnisse hervorhebt.}, subject = {Kaltes Plasma}, language = {de} } @phdthesis{Renner, author = {Renner, Sebastian}, title = {Secure Lightweight Authenticated Encryption for Critical Infrastructures in the Internet of Things}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:91-diss-20230922-1703211-1-0}, pages = {xix, 135}, abstract = {The cryptographic protection of transmitted data on resource-constraint IoT devices presents a difficult challenge. In this thesis, a benchmarking framework for the performance evaluation of lightweight encryption algorithms is introduced. It is analyzed, if and when novel encryption algorithms are more suitable for IoT use cases than the current standard. Besides comparing the sole performance, the cost for hardening the algorithms against side-channel analysis is discussed.}, language = {en} } @phdthesis{Thema, author = {Thema, Martin Jiř{\´i}}, title = {Process optimization for microbial biosynthesis of methane in a trickle-bed reactor for Power-to-Gas applications: the ORBIT-process}, isbn = {978-3-8440-7656-1}, url = {http://nbn-resolving.de/https://nbn-resolving.org/urn:nbn:de:bvb:29-opus4-150567}, pages = {XVIII, 211}, abstract = {This thesis identifes Power-to-Gas in general and biological CO2-methanation in trickle-bed reactors in particular as promising energy storage and sector coupling technology ready for application but with further optimization potential. It reviews the global status and development of Power-to-Gas technology as to be of exponentially growing importance in energy systems changing towards renewable power supply and analyzes optimization and standardization potential for biological CO2-methanation in tricklebed reactors deriving an improved methanation process. Process development and experiments on hydrodynamical and biological improvement of such a setup were performed, leading to an optimized combination of a packing and microorganisms in pure culture embedded in the new ORBIT-process. First experimental results give evidence of successful application of different optimization approaches implemented in a technical center scale setup.}, language = {en} } @phdthesis{Stadler, author = {Stadler, Sebastian Rudolf Johann}, title = {The integration of virtual reality into the design process}, url = {http://nbn-resolving.de/https://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:91-diss-20211103-1612177-1-3}, pages = {VIII, 205}, abstract = {Technological advances strive towards automation and digitalization with the aim to increase efficiency in terms of decreased costs and product development time, resulting in shorter product life cycles. As this causes industries to release products more frequently and more quickly, industrial designers face problems in developing more complex systems in a decreased amount of time while aiming to meet individualized user requirements and stakeholder demands. If prototypes are infeasible or unaffordable, a successful market implementation of products is jeopardized. As design history proves, the introduction of new technologies to the profession of design has the potential to revolutionize the way of working for industrial designers. Virtual Reality may be one of these revolutions, as Computer-Aid Design has been in the 1980s. The present dissertation investigates the integration of Virtual Reality and its impact on the design process, the respective design method, but also the designer and design as a profession. After defining industrial design and Virtual Reality, a basic framework is proposed that describes a design process consensus model, the transfer of conventional design methods into VR, as well as a preliminary set of criteria for evaluating design studies. Based on this framework, four research questions are defined that initiate the investigation of how Virtual Reality can impact the design process, design methods, the role of designers, and design as a profession. To allow this, a refined set of criteria for evaluating design studies is developed and a benchmark study is conducted that proves the suitability for using Virtual Reality in the chosen context. Subsequently, five design studies are conducted in the field of autonomous mobility for public transport in Singapore to investigate the previously defined questions. The five design methods that are combined with Virtual Reality are heuristic evaluation, surveys, Computer-Aided Design prototyping, usability testing, and product presentation. For each design study, the development of the VR apparatus as well as the data collection and test of the method is explained. Additionally, two conventional design methods are consulted for a subsequent comparative analysis of each VR methods. Beyond the definition of the refined evaluation criteria, consisting of safety, validity, time and cost, variability, interactivity, immersion, and effort, the suitability of using VR for behavioural observation in the present application domain is confirmed. Based on the present investigations, the Virtual Design Toolbox is presented. The toolbox consists of five method cards that explain the usage of Virtual Reality for industrial designers throughout the product development and function as support for successfully developing and applying design methods utilizing this technology. The case studies prove that the usage of Virtual Reality has the potential to impact the design process, as divergent thinking and convergent thinking is fostered through valid data collection, decreased time- and cost- involvement, and increased variability. The roles of the involved designers throughout all design studies shifted from being concept creators towards coordinators and facilitators. Implications are derived on different levels, starting with the technology of Virtual Reality that could be a future game changer for research and design, followed by increased motivation to participate in design studies, the need for interdisciplinary teams to establish the required expertise, and lastly integration of Virtual Reality in design education. The usage of Virtual Reality in design will not replace conventional design methods but has the potential to lead to a paradigm shift for the whole profession of design.}, language = {en} } @misc{AppeltFautz, author = {Appelt, Andreas and Fautz, Anna}, title = {Optimierung Offenporiger Asphalte f{\"u}r Geh- und Radwegbereiche unter dem Aspekt der Schwammstadt}, address = {Regensburg}, pages = {47}, abstract = {Ans{\"a}tze zur planerische und bautechnische Optimierungen von inner{\"o}rtlichen Geh- und Radwegen mit Einsatz von Offenporigen Asphalten unter dem Aspekt der Schwammstadt}, language = {de} } @misc{OPUS4-7895, title = {Production Scheduling and Planning in Manufacturing Systems}, series = {Systems}, volume = {2025}, journal = {Systems}, editor = {Herrmann, Frank}, publisher = {MDPI}, address = {Basel}, issn = {2079-8954}, language = {en} } @misc{LehrerStockerDuddecketal., author = {Lehrer, Tobias and Stocker, Philipp and Duddeck, Fabian and Wagner, Marcus}, title = {Parametric CAD Models to Create an Infinite Number of Structural U-Shaped Sheet Metal Geometries [Data set]}, doi = {10.5281/ZENODO.14191374}, abstract = {The U-Channel Software is a python package containing four parametric models of U-shaped Sheet metals. The parameters refer to geometric dimensions, angles, fillet radii. Using the models, one can generate an infinite number of U-shaped sheet metal geometries, e.g. as STEP files. The parametric models are inspired by real-world shapes. A feasibility check is provided to ensure plausiblity of the shapes. Further features of the code are creating images of the geometries and generating geometries and images in parallel. For more details, refer to the repository and associated publications.}, language = {en} } @inproceedings{RauchBruecklEngel, author = {Rauch, Johannes and Br{\"u}ckl, Oliver and Engel, Bernd}, title = {Optimal Reactive Power Planning by covering deficient voltage demands with additional reactive power sources using a sensitivity approach}, series = {NEIS 2023 : Conference on Sustainable Energy Supply and Energy Storage Systems, Hamburg, September 4 - 5, 2023}, booktitle = {NEIS 2023 : Conference on Sustainable Energy Supply and Energy Storage Systems, Hamburg, September 4 - 5, 2023}, editor = {Schulz, Detlef,}, publisher = {VDE Verlag}, address = {Berlin}, isbn = {978-3-8007-6134-0}, pages = {223 -- 230}, abstract = {The determination of the optimal location, types and size of additional required reactive power sources is a main interest of Reactive Power Planning (RPP) investigations and of this paper. The planning problem addresses the maintenance of voltage stability, which is an ancillary service in Germany, and can be formulated as a mixed-integer optimization prob-lem. The aim of this work is a techno-economically efficient coverage of the deficient steady state voltage deviation demands (VDD) by placing new reactive power sources with adequate size or extending the reactive power potential of existing sources. An optimization model is set up to solve the planning problem by using load flow voltage sensitivities, which quantify and evaluate the technical efficiency of new reactive power sources in relation to the present voltage deviation demands. Operating and investment costs are used as economic decision parameters. Within an application example, which is carried out with an exemplary transmission system, the solution of the planning problem is discussed.}, language = {en} } @inproceedings{HinterreiterBruecklRauch, author = {Hinterreiter, Marion and Br{\"u}ckl, Oliver and Rauch, Johannes}, title = {Challenges and Approaches for Long-Term Reactive Power Forecasting in Power Systems}, series = {PESS 2025 - IEEE Power and Energy Student Summit, October 08 - 10, 2025 in Munich, Germany}, booktitle = {PESS 2025 - IEEE Power and Energy Student Summit, October 08 - 10, 2025 in Munich, Germany}, editor = {Technische Universit{\"a}t M{\"u}nchen,}, publisher = {VDE Verlag}, isbn = {978-3-8007-6656-7}, pages = {109 -- 114}, abstract = {The transition from fossil fuels to renewable energy sources is driving profound changes across all voltage levels of the electrical grid, altering active power (P) as well as reactive power (Q) behavior. This transformation involves a shift from predominantly top-down, unidirectional electricity flows to bidirectional and increasingly complex flow patterns, fundamentally altering the operation and utilization of power systems. Many countries are already reporting notable changes in their transmission grid Q. This can lead to increased costs for grid expansion and compensation equipment, as well as grid losses. To minimize these losses and ensure grid stability and efficiency, understanding and forecasting Q long-term becomes essential. This paper addresses the challenges of long-term (1-20 years) Q forecasting in general by analyzing Q behavior in grids, the main influencing grid parameters, and reviewing existing forecasting approaches. It evaluates the applicability of these approaches and highlights current research gaps and trends. By focusing on this underexplored area, the paper aims to support the development of more advanced and reliable long-term Q forecasting techniques.}, language = {en} } @inproceedings{HinterreiterBruecklRauch, author = {Hinterreiter, Marion and Br{\"u}ckl, Oliver and Rauch, Johannes}, title = {Methodology for long-term reactive power forecasts of medium-voltage grids}, series = {NEIS 2025 : Conference on Sustainable Energy Supply and Energy Storage Systems, Hamburg, September 15 - 16, 2025}, booktitle = {NEIS 2025 : Conference on Sustainable Energy Supply and Energy Storage Systems, Hamburg, September 15 - 16, 2025}, editor = {Schulz, Detlef}, publisher = {VDE Verlag}, isbn = {978-3-8007-6633-8}, pages = {218 -- 223}, abstract = {Understanding and assessing the long-term behavior of reactive power is crucial for power system planning and invest-ment decisions. This is particularly growing relevant for the lower voltage-grid levels, which are gaining importance due to significant changes in grid behavior, operational strategies, energy generation and consumption patterns. Currently, standardized methodologies for forecasting reactive power in medium-voltage grids are lacking, creating a gap in research and practical applications. To optimize grid investments and expansions, informed decisions based on reliable research and accurate forecasts are essential. This paper presents a methodology for long-term reactive power forecasting in me-dium-voltage grids, introducing a new approach to account for low- and medium-voltage grid interactions while address-ing common challenges like limited available grid data and scenario framework definition. The aim of the forecast is the future reactive power behaviour of a medium-voltage-grid at the high-voltage side of the high-voltage to medium-voltage transformer. The medium-voltage-level is modelled using a grid model approach, while low-voltage grids are being mod-elled using generic distribution grids. A 209-bus medium-voltage-grid model is used as an application example and to provide two exemplary use cases for a reactive power forecast for 2045.}, language = {en} } @inproceedings{StadlerKrausBrueckl, author = {Stadler, Andreas and Kraus, Hermann and Br{\"u}ckl, Oliver}, title = {Proposing an Optimization Model for a techno-economic Evaluation of Energy Storage Systems}, series = {PESS 2025 - IEEE Power and Energy Student Summit, October 08 - 10, 2025 in Munich, Germany}, booktitle = {PESS 2025 - IEEE Power and Energy Student Summit, October 08 - 10, 2025 in Munich, Germany}, editor = {Technische Universit{\"a}t M{\"u}nchen,}, publisher = {VDE}, isbn = {978-3-8007-6656-7}, pages = {97 -- 102}, abstract = {During the global energy crisis in 2022, electricity prices increased drastically. This lead, together with an overall higher price volatility to possibly higher electrical energy storage system (ESS) profitability. To test if the investment in an ESS can now be more profitable, an approach for a techno-economic evaluation of ESS is presented in this paper, using an optimization algorithm to determine the optimal way of covering a load flow profile with electricity trading products on the electricity market with and without the use of an energy storage system. The cost differences between using or not using the storage system are assumed to be the profits of the ESS, which must exceed the (interest-bearing) investment costs over its lifetime. The correct way of operation of the optimization model is validated and several storage sizes and capacities as well as several years of the electricity market data was analyzed, once with a perfect forecast of all prices of the electricity trading products and once with a forecast based on the previous years purchasing strategy. The results show that, using the prognosis and a 2 \% p.a. interest rate, only the storage combinations for 2.5 MWh/ 2.5 MW and 1 MWh/ 1 MW show profitability in 2023, whereas 2017 and 2020 show no profitability.}, language = {en} } @inproceedings{UhlSchamelAchhammeretal., author = {Uhl, Julius and Schamel, Marco and Achhammer, Anton and Sterner, Michael}, title = {Sustainable Steel Production in the Desert: Economic and Technical Assessment of a Hydrogen-Powered Steel Plant in Mauritania}, series = {2025 IEEE PES/IAS PowerAfrica, 28 September - 02 October 2025, Cairo}, booktitle = {2025 IEEE PES/IAS PowerAfrica, 28 September - 02 October 2025, Cairo}, publisher = {IEEE}, doi = {10.1109/PowerAfrica65840.2025.11289120}, pages = {6}, abstract = {The global steel industry is a major contributor to climate change and faces challenges in achieving a carbon-neutral production, hinging on the availability of cost-effective hydrogen produced by renewable energy. Mauritania, with its exceptional solar and wind resources, offers some of the most competitive conditions globally for hydrogen production. Instead of focusing on hydrogen exports, this study explores the technical feasibility and economic viability of establishing a renewable-powered steel plant in Mauritania, utilizing the country's abundant iron ore reserves. The findings suggest that sustainably produced steel in Mauritania could be cost-competitive with current European prices. With ongoing declines in investment costs for emerging renewable technologies, Mauritania has the potential to become one of the world's most cost-effective steel producers.}, language = {en} } @article{SittlMarburgDeckersetal., author = {Sittl, Christopher and Marburg, Steffen and Deckers, Elke and Wagner, Marcus}, title = {Model order reduction for unbounded second-order vibroacoustic systems using infinite elements and Dirichlet-to-Neumann map}, series = {Computer Methods in Applied Mechanics and Engineering}, volume = {453}, journal = {Computer Methods in Applied Mechanics and Engineering}, publisher = {Elsevier}, doi = {10.1016/j.cma.2026.118846}, pages = {22}, abstract = {This work addresses the efficient numerical simulation of time-harmonic vibroacoustic problems in unbounded domains, with a focus on fluid-structure interaction. The underlying mathematical model is a second-order dynamical system arising from the coupling of structural and acoustic domains, incorporating material damping effects, relevant in structural acoustics and noise control applications. A central novelty of the proposed method is its unified computational framework that supports two distinct strategies for treating unbounded fluid domains: (1) non-local absorbing boundary conditions based on Dirichlet-to-Neumann map, and (2) infinite elements, which extend the computational domain rather than truncate it. Both approaches are integrated into a consistent formulation that enables flexible and accurate modeling of exterior wave propagation. To efficiently evaluate frequency-domain transfer functions, the method employs model order reduction using the Pad{\´e}-via-Lanczos technique. While this algorithm typically targets first-order systems, the present approach uses a Schur complement strategy to reduce the second-order system in a way that maintains computational efficiency and storage requirements comparable to first-order formulations. Importantly, the framework seamlessly embeds both interior structural damping and the additional dissipation introduced by the acoustic-domain truncation into the model-order reduction process. The exterior acoustic field is represented via spherical harmonic expansions, with expansion coefficients computed from the reduced system. Numerical results demonstrate the method's accuracy, efficiency, and scalability, making it well-suited for high-fidelity vibroacoustic analysis in unbounded domains.}, language = {en} } @book{FinckhKreutzEberth, author = {Finckh, Wolfgang and Kreutz, Johannes and Eberth, Florian}, title = {Br{\"u}ckenverst{\"a}rkung mit geklebter Bewehrung}, publisher = {Springer Vieweg}, address = {Wiesbaden}, isbn = {9783658492571}, doi = {10.1007/978-3-658-49258-8}, pages = {XVII, 317}, abstract = {Dieses Buch widmet sich der Verst{\"a}rkung von Stahlbeton- und Spannbetonbr{\"u}cken mit geklebter Bewehrung. Dazu werden zun{\"a}chst die verschieden Verst{\"a}rkungsgr{\"u}nde f{\"u}r Br{\"u}cken sowie deren Beanspruchungsarten vorgestellt. Danach werden die Anwendungsm{\"o}glichkeiten der geklebten Bewehrung vorgestellt und die rechnerischen Herausforderungen sowie der L{\"o}sungsm{\"o}glichkeiten erl{\"a}utert. Im n{\"a}chsten Kapitel wird vertieft auf die rechnerischen Besonderheiten von Spannbetonverst{\"a}rkungen mit geklebter Bewehrung eingegangen. Da f{\"u}r die Verbundnachweise der geklebten Bewehrung im Br{\"u}ckenbau einen Betriebsfestigkeit notwendig ist, wird dieser zun{\"a}chst am Stahlbetonbauteil erl{\"a}utert. Danach werden die erforderlichen Erm{\"u}dungsnachweise f{\"u}r aufgeklebte und eingeklebte Bewehrung im Br{\"u}ckenbau behandelt. Abschließend wird noch ein Verfahren vorgestellt, wie spannungsrisskorrosionsgef{\"a}hrdete Bauteile verst{\"a}rkt werden k{\"o}nnen. Die im Buch vorgestellten theoretischen Grundlagen werden anhand zahlreicher Abbildungen verdeutlicht. Zu jedem Thema sind zum besseren Verst{\"a}ndnis umfangreiche Bemessungsbeispiele mit Praxisbezug enthalten.}, language = {de} } @book{Finckh, author = {Finckh, Wolfgang}, title = {Mit Stabwerkmodellen zur Bewehrungsf{\"u}hrung: Detailnachweise im Stahlbetonbau}, series = {erfolgreich studieren}, journal = {erfolgreich studieren}, edition = {2. Auflage}, publisher = {Springer Fachmedien}, address = {Wiesbaden}, isbn = {9783658488550}, issn = {2524-8693}, doi = {10.1007/978-3-658-48856-7}, pages = {XIV, 465}, abstract = {Aufbauend auf den Grundlagen des Stahlbetonbaus wird in diesem Lehrbuch das Konzept der Bemessung von Stahlbetonkonstruktionen mittels Stabwerkmodellen erl{\"a}utert. Dieses Bemessungskonzept wird insbesondere im Bereich der Detailnachweise und bei gedrungenen Tragwerken im Stahlbetonbau ben{\"o}tigt. Neben der generellen Modellbildung und Nachweismethodik werden auch die {\"u}blichen Modelle und Nachweise f{\"u}r h{\"a}ufig vorkommende Details vorgestellt. Hierbei werden insbesondere Krafteinleitungsbereiche, Konsolen, ausgeklinkte Auflager, Rahmenknoten, Querschnittsspr{\"u}nge, Tr{\"a}ger{\"o}ffnungen, Wandartige Tr{\"a}ger, K{\"o}cherfundamente und Pfahlkopfplatte detailliert behandelt. Die im Lehrbuch vorgestellten theoretische Grundlagen werden anhand zahlreicher Abbildungen erl{\"a}uterten. In jedem Kapitel sind zum besseren Verst{\"a}ndnis umfangreiche Bemessungsbeispiele mit Praxisbezug enthalten.}, language = {de} } @article{SchiekSolntsevNeshev2025, author = {Schiek, Roland and Solntsev, Alexander S. and Neshev, Dragomir N.}, title = {Measurement of the cubic nonlinear susceptibility in lithium niobate}, series = {Optical Materials Express}, volume = {15}, journal = {Optical Materials Express}, number = {5}, publisher = {Optica Publishing Group}, issn = {2159-3930}, doi = {10.1364/OME.557516}, pages = {1100 -- 1117}, year = {2025}, abstract = {We measured the cubic nonlinear susceptibility tensor elements ( χ(3)) for polarization along the primary crystallographic axis in titanium-indiffused lithium niobate waveguides, assessed through self-phase modulation using picosecond-duration pulses at telecommunication wavelengths. A dominant, highly temperature- and wavelength-dependent contribution from a cascaded second-order nonlinearity is observed. Through careful extraction of the cascaded effect, we quantify the intrinsic third-order susceptibility tensor elements as χ(3) zzzz(ω; ω, ω, -ω) = (5.2 ± 1.3) × 10-21 m2 V2 and χ(3) xxxx(ω; ω, ω, -ω) = χ(3) yyyy(ω; ω, ω, -ω) = (3.6 ± 0.8) × 10-21 m2 V2 . These measurements underscore the substantial impact of the cascaded nonlinearity in enhancing the effective cubic nonlinearity in lithium niobate and offer precise values essential for the design of nonlinear photonic devices.}, language = {en} } @article{LinnerdeSotoElMahdyetal., author = {Linner, Thomas and de Soto, Borja Garc{\´i}a and El-Mahdy, Deena and Gonzalez, Vicente A.}, title = {Topical collection: robotic solutions for digitally enabled production processes in construction}, series = {Construction Robotics}, volume = {10}, journal = {Construction Robotics}, publisher = {Springer}, issn = {2509-811X}, doi = {10.1007/s41693-025-00174-w}, pages = {1}, abstract = {Across the global construction sector, a new generation of robotic systems is rapidly entering the market. Solutions for on-site drilling, spraying, masonry, logistics, and finishing are now being piloted at an unprecedented pace. Their deployment in emerging construction robotics hubs in Singapore, Hong Kong, Canada, Dubai, Abu Dhabi, Egypt, Denmark, Switzerland, and Germany demonstrates both the momentum of this technological shift and the considerable challenges that remain. In real-world testing environments, the integration of these robots into digital construction pipelines—particularly BIM-to-robot workflows, semantic task modeling, and robust digital twins—continues to be a bottleneck. These challenges position digitally enabled fabrication and robotics as a priority topic within academia, motivating research on methods, techniques, algorithms, and workflows that can accelerate adoption in construction. This Topical Collection brings together research spanning the emerging landscape of digitally enabled construction robotics. The contributions advance robotic fabrication, from flexible timber processes to innovative formwork, reinforcement, and earth-based additive methods, alongside computer vision, BIM integration, and sensing approaches that improve monitoring and quality assurance. The collection also includes mobile and aerial systems for inspection and mapping to support system autonomy in construction. Together, these works show how integrated perception, planning, and sociotechnical understanding of human-robot collaboration are becoming essential for reliable robotic performance in construction. While current construction robots still focus on simple, structured tasks, the advances in this topical collection point toward a more capable generation. Contributions outline principles for robot-compatible buildings through new fabrication logics and BIM-linked task data, while work on perception, BIM integration, and data fusion reduces interoperability gaps. Research on sensing and adaptive processes supports more consistent workflows, and mobile and aerial robotics provide insights for deployment and site logistics. Collectively, these developments show how digitally enabled production processes can help to overcome key systemic barriers and enable future, scalable construction robotics.}, language = {en} } @article{WeindlerDawoud, author = {Weindler, Jeremy and Dawoud, Belal}, title = {Experimental investigation of a small-scale continuous flow ohmic heating reactor for a highly effective conversion of renewable electricity surpluses into heat}, series = {Applied Thermal Engineering}, volume = {242}, journal = {Applied Thermal Engineering}, publisher = {Elsevier}, issn = {1359-4311}, doi = {10.1016/j.applthermaleng.2024.122401}, pages = {15}, abstract = {Sector coupling is expected to play a decisive role as a key technology to realize the energy transition towards green energy supply. This work introduces, therefore, a comprehensive experimental study on a new power-to-heat system based on the continuous-flow, ohmic heating principle, which aims at utilizing renewable electricity in green processes. The ohmic heating technology, which is widely applied in the food industry, has been adapted and evaluated for delivering heat and domestic hot water to a single-family house. The introduced prototype is designed to convert renewable electricity into heat in the power range between 1000 and 3000 W with a typical electrical household installation (230 V, 50 Hz and 16 A fuse). A dedicated test rig has been developed and a comprehensive experimental campaign has been carried out to investigate the performance of the introduced system under typical operating conditions of a single-family house. Both the conversion efficiency and the dynamics of the thermal response of the introduced system have been assessed. It turned out that, the temperature lift between the return and supply of the reactor, and consequently, the conversion efficiency of electrical into thermal energy, are independent on the return temperature, for a fixed value of the volume flow rate of the electrolyte solution. A remarkable steady-state conversion efficiency of 97.5\% has been measured. In addition, the dynamic response of the ohmic heating system has been found to be strongly dependent on the desired temperature lift. By an implemented controller, 95\% of the steady state temperature lift of 44.5 K can be realized in 50 s, which marks an exceptionally rapid thermal response. The obtained results pave the way towards a field test study of the developed technology in a real household installation as well as to extend the focus on new fields such as green chemical processes.}, language = {en} }