@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} }