TY - JOUR AU - Höpfner, Henning AU - Fritsche, Carola AU - Ludwig, Arne AU - Ludwig, Astrid AU - Stromberg, Frank AU - Wende, Heiko AU - Keune, Werner AU - Reuter, Dirk AU - Wieck, Andreas D. AU - Gerhardt, Nils C. AU - Hofmann, Martin R. ID - 7301 IS - 11 JF - Applied Physics Letters SN - 0003-6951 TI - Magnetic field dependence of the spin relaxation length in spin light-emitting diodes VL - 101 ER - TY - JOUR AU - Varwig, S. AU - Schwan, A. AU - Barmscheid, D. AU - Müller, C. AU - Greilich, A. AU - Yugova, I. A. AU - Yakovlev, D. R. AU - Reuter, Dirk AU - Wieck, A. D. AU - Bayer, M. ID - 7302 IS - 7 JF - Physical Review B SN - 1098-0121 TI - Hole spin precession in a (In,Ga)As quantum dot ensemble: From resonant spin amplification to spin mode locking VL - 86 ER - TY - JOUR AU - Ganczarczyk, A. AU - Rojek, S. AU - Quindeau, A. AU - Geller, M. AU - Hucht, A. AU - Notthoff, C. AU - König, J. AU - Lorke, A. AU - Reuter, Dirk AU - Wieck, A. D. ID - 7303 IS - 8 JF - Physical Review B SN - 1098-0121 TI - Transverse rectification in density-modulated two-dimensional electron gases VL - 86 ER - TY - JOUR AU - Beckel, Andreas AU - Zhou, Daming AU - Marquardt, Bastian AU - Reuter, Dirk AU - Wieck, Andreas D. AU - Geller, Martin AU - Lorke, Axel ID - 7312 IS - 23 JF - Applied Physics Letters SN - 0003-6951 TI - Momentum matching in the tunneling between 2-dimensional and 0-dimensional electron systems VL - 100 ER - TY - JOUR AU - Schwan, A. AU - Varwig, S. AU - Greilich, A. AU - Yakovlev, D. R. AU - Reuter, Dirk AU - Wieck, A. D. AU - Bayer, M. ID - 7313 IS - 23 JF - Applied Physics Letters SN - 0003-6951 TI - Non-resonant optical excitation of mode-locked electron spin coherence in (In,Ga)As/GaAs quantum dot ensemble VL - 100 ER - TY - JOUR AU - Buchholz, Sven S. AU - Sternemann, Elmar AU - Chiatti, Olivio AU - Reuter, Dirk AU - Wieck, Andreas D. AU - Fischer, Saskia F. ID - 7315 IS - 23 JF - Physical Review B SN - 1098-0121 TI - Noise thermometry in narrow two-dimensional electron gas heat baths connected to a quasi-one-dimensional interferometer VL - 85 ER - TY - JOUR AU - Kurtze, H. AU - Yakovlev, D. R. AU - Reuter, Dirk AU - Wieck, A. D. AU - Bayer, M. ID - 7324 IS - 19 JF - Physical Review B SN - 1098-0121 TI - Hyperfine interaction mediated exciton spin relaxation in (In,Ga)As quantum dots VL - 85 ER - TY - JOUR AU - Schuster, J AU - Kim, T Y AU - Batke, E AU - Reuter, Dirk AU - Wieck, A D ID - 7325 IS - 16 JF - Journal of Physics: Condensed Matter SN - 0953-8984 TI - Photoluminescence lineshape features of carbon δ-doped GaAs heterostructures VL - 24 ER - TY - JOUR AU - Bryja, L. AU - Jadczak, J. AU - Wójs, A. AU - Bartsch, G. AU - Yakovlev, D. R. AU - Bayer, M. AU - Plochocka, P. AU - Potemski, M. AU - Reuter, Dirk AU - Wieck, A. D. ID - 7326 IS - 16 JF - Physical Review B SN - 1098-0121 TI - Cyclotron-resonant exciton transfer between the nearly free and strongly localized radiative states of a two-dimensional hole gas in a high magnetic field VL - 85 ER - TY - JOUR AU - Huang, J. AU - Chen, Y. S. AU - Ludwig, A. AU - Reuter, Dirk AU - Wieck, A. D. AU - Bacher, G. ID - 7327 IS - 13 JF - Applied Physics Letters SN - 0003-6951 TI - Electron-nuclei spin coupling in GaAs—Free versus localized electrons VL - 100 ER - TY - JOUR AU - Houel, J. AU - Kuhlmann, A. V. AU - Greuter, L. AU - Xue, F. AU - Poggio, M. AU - Gerardot, B. D. AU - Dalgarno, P. A. AU - Badolato, A. AU - Petroff, P. M. AU - Ludwig, A. AU - Reuter, Dirk AU - Wieck, A. D. AU - Warburton, R. J. ID - 7329 IS - 10 JF - Physical Review Letters SN - 0031-9007 TI - Probing Single-Charge Fluctuations at aGaAs/AlAsInterface Using Laser Spectroscopy on a Nearby InGaAs Quantum Dot VL - 108 ER - TY - JOUR AU - Chen, J. C. H. AU - Wang, D. Q. AU - Klochan, O. AU - Micolich, A. P. AU - Das Gupta, K. AU - Sfigakis, F. AU - Ritchie, D. A. AU - Reuter, Dirk AU - Wieck, A. D. AU - Hamilton, A. R. ID - 7330 IS - 5 JF - Applied Physics Letters SN - 0003-6951 TI - Fabrication and characterization of ambipolar devices on an undoped AlGaAs/GaAs heterostructure VL - 100 ER - TY - CONF AU - Höpfner, Henning AU - Li, Mingyuan AU - Ludwig, Arne AU - Ludwig, Astrid AU - Stromberg, Frank AU - Wende, Heiko AU - Keune, Werner AU - Reuter, Dirk AU - Wieck, Andreas D. AU - Gerhardt, Nils C. AU - Hofmann, Martin R. ID - 7334 T2 - Ultrafast Phenomena and Nanophotonics XVI TI - Room temperature spin relaxation in quantum dot based spin-optoelectronic devices ER - TY - JOUR AU - Li, Yan AU - Sinitsyn, N. AU - Smith, D. L. AU - Reuter, Dirk AU - Wieck, A. D. AU - Yakovlev, D. R. AU - Bayer, M. AU - Crooker, S. A. ID - 7338 IS - 18 JF - Physical Review Letters SN - 0031-9007 TI - Intrinsic Spin Fluctuations Reveal the Dynamical Response Function of Holes Coupled to Nuclear Spin Baths in (In,Ga)As Quantum Dots VL - 108 ER - TY - JOUR AU - Dumslaff, Uwe AU - Engels, Gregor AU - Kremer, Marion ID - 7339 IS - Nr. 5 JF - OBJEKTspektrum TI - IT ist nicht gleich IT: Ein Plädoyer für eine situationsbezogene Softwareentwicklung ER - TY - JOUR AU - Luckey, Markus AU - Erwig, Martin AU - Engels, Gregor ID - 7340 IS - 5 JF - Journal of Visual Languages & Computing SN - 1045-926X TI - Systematic evolution of model-based spreadsheet applications VL - 23 ER - TY - JOUR AU - Chernilovskaya, Anna AU - Gehrke, Mai AU - van Rooijen, Lorijn ID - 7342 IS - 6 JF - Logic Journal of IGPL SN - 1367-0751 TI - Generalized Kripke semantics for the Lambek-Grishin calculus VL - 20 ER - TY - JOUR AU - Grieger, Marvin AU - Güldali, Baris AU - Sauer, Stefan ID - 7344 IS - 2 JF - Softwaretechnik-Trends, Proceedings of the 14th Workshop Software-Reengineering (WSR) TI - Sichern der Zukunftsfähigkeit bei der Migration von Legacy-Systemen durch modellgetriebene Softwareentwicklung VL - 32 ER - TY - JOUR AU - Engels, Gregor AU - Whittle, Jon ID - 7345 IS - 4 JF - Software & Systems Modeling SN - 1619-1366 TI - Ten years of software and systems modeling VL - 11 ER - TY - JOUR AU - Christ, Fabian AU - Nagel, Benjamin AU - Bachman-Gmür, Reto AU - Westenthaler, Rupert ID - 7351 JF - JavaMagazin TI - Semantisches Content Management VL - 8 ER - TY - JOUR AB - Mittlerweile sind viele Unternehmen dazu übergegangen, ihre Software „agil“ zu entwickeln. Die damit verbundenen Erwartungen sind vor allem ein frühes Kundenfeedback sowie eine kürzere „Time-to-Market“ durch entsprechend schnelle Release-Zyklen. Hinter den Kulissen finden sich jedoch oftmals Probleme, sodass die erwarteten Vorteile agiler Softwareentwicklung nicht oder nur teilweise zum Tragen kommen. Gründe dafür liegen selten an technischen Hürden, sondern oftmals in einer zu oberflächlichen Interpretation der Philosophie von agiler Softwareentwicklung und den damit zusammenhängenden Kernzielen: Planung und Analyse auf ein sinnvolles Maß zu reduzieren und zugleich unnötige Arbeiten zu vermeiden. Was sinnvoll und was unnötig ist, stellt dabei eine der wesentlichen Herausforderungen dar. AU - Geisen, Silke AU - Güldali, Baris ID - 7352 IS - Agility/2012 JF - OBJEKTspektrum (Online Themenspecials) TI - Agiles Testen in Scrum – Testtypen und Abläufe ER - TY - JOUR AU - Ruth, Marcel AU - Meier, Cedrik ID - 7490 IS - 22 JF - Physical Review B SN - 1098-0121 TI - Scaling coefficient for three-dimensional grain coalescence of ZnO on Si(111) VL - 86 ER - TY - JOUR AU - Kröger, Philipp AU - Ruth, Marcel AU - Weber, Nils AU - Meier, Cedrik ID - 7491 IS - 26 JF - Applied Physics Letters SN - 0003-6951 TI - Carrier localization in ZnO quantum wires VL - 100 ER - TY - JOUR AU - Kampmeier, J. AU - Rashad, M. AU - Woggon, U. AU - Ruth, M. AU - Meier, Cedrik AU - Schikora, D. AU - Lischka, K. AU - Pawlis, A. ID - 7492 IS - 15 JF - Physical Review B SN - 1098-0121 TI - Enhanced photoluminescence of colloidal nanocrystals embedded in epitaxially grown semiconductor microstructures VL - 85 ER - TY - BOOK AU - Kremer, Marion AU - Engels, Gregor AU - Hofmann, Alexander AU - Hohwiller, Jörg AU - E. Nandico, Oliver AU - Nötzold, Thomas AU - Prott, Karl AU - Schlegel, Diethelm AU - Seidl, Andreas AU - Wolf, Thomas ID - 7507 TI - Quasar 3.0 - A Situational Approach to Software Engineering ER - TY - CHAP AB - Software systems are part of our everyday life and they become more complex day by day. The ever-growing complexity of software and high quality requirements pose tough challenges to quality assurance. The quality of a software system can be measured by software testing. However, if manually done, testing is a time-consuming and error-prone task. Especially test case design and test execution are the most cost-intensive activities in testing. In the previous 20 years, many automation tools have been introduced for automating test execution by using test scripts. However, the effort for creating and maintaining test scripts remains. Model-based testing (MBT) aims at improving this part by systematizing and automating the test case design. Thereby, test cases or automatable test scripts can be generated systematically from test models. MBT is already known for several years, but it currently gains a great momentum due to advanced tool support and innovative methodological approaches. This chapter aims at giving an overview of MBT and summarizes recent achievements in MBT. Experiences with using the MBT approach are illustrated by reporting on some success stories. Finally, open issues and future research challenges are discussed. AU - Mlynarski, Michael AU - Güldali, Baris AU - Weißleder, Stephan AU - Engels, Gregor ED - Hurson, Ali ED - Memon, Atif ID - 7557 T2 - Advances in Computers TI - Model-Based Testing: Achievements and Future Challenges VL - 86 ER - TY - THES AB - Software-Architekturen betrieblicher Informationssysteme bestehen aus Architekturbausteinen wie Frameworks, Komponenten und Bibliotheken. Die Entwicklung dieser Architekturen unter Einbeziehung wiederverwendbarer Architekturbausteine ist eine Voraussetzung einer industriell organisierten Software-Entwicklung. Für eine effiziente Trennung der Zuständigkeiten werden dabei häufig Architekturbausteine von Drittanbietern wiederverwendet.Frameworks als erweiterbare Architekturbausteine bieten besondere Vorteile. Sie erlauben sowohl die Wiederverwendung der Funktionalität als auch der durch das Framework vorgegebenen Software-Architektur. Beispiele sind Frameworks für Benutzungsoberflächen oder für die Anbindung von Datenbanken. Durch Implementierung anwendungsspezifischer Erweiterungen wird ein Framework für den konkreten Anwendungsfall angepasst. Eine Anwendung, deren Software-Architektur ein Framework einsetzt, benutzt das Framework über dessen Erweiterungspunkte.Im Laufe der Evolution einer solchen Anwendung entsteht häufig die Situation, dass das Framework durch eine neuere Version aktualisiert werden soll. Die Aktualisierung enthält das Risiko, dass Inkompatibilitäten zwischen bestehender Anwendung und neuer Framework-Version auftreten, die wiederum zu aufwendigen Anpassungen führen. Daher müssen mögliche Inkompatibilitäten vor der Aktualisierung erkannt und bewertet werden. Nach aktuellem Stand der Technik ist dies nicht möglich, so dass es in der industriellen Praxis zu unvorhergesehenen Problemen verbunden mit hohen Kosten kommt.Wir stellen ein Verfahren zur automatischen Kompatibilitätsanalyse Framework-basierter Anwendungen vor, mit dem das beschriebene Problem gelöst wird. Durch eine Kombination aus Codeanalyse und neuartiger Framework-Beschreibung lassen sich mögliche Inkompatibilitäten vor Durchführung der Aktualisierung automatisch berechnen. Eine prototypische Implementierung des Verfahrens im Werkzeug »Companian« demonstriert die praktische Einsetzbarkeit unseres Verfahrens.Für die Definition der benötigten Framework-Beschreibungssprache mittels Meta-Modellierung setzen wir die neuartige Modellierungstechnik der parametrisierten Meta-Modelle ein. Die Technik unterstützt unseren Ansatz einer anforderungsbasierten Wiederverwendung von Sprachen. Mit diesem Ansatz können bestehende Sprachen für Teilaspekte neu definierter Sprachen wiederverwendet werden. Unser pragmatischer Ansatz stellt dabei sicher, dass hierbei nur die Sprachen benutzt werden können, die syntaktisch und semantisch den geforderten Sprachen entsprechen. AU - Christ, Fabian ID - 7572 TI - Automatische Kompatibilitätsprüfung Framework-basierter Anwendungen ER - TY - CONF AU - Gerth, Christian AU - Luckey, Markus ID - 8473 IS - 4 T2 - Proceedings of the Workshop on Comparison and Versioning of Software Models (CVSM'12) TI - Towards Rich Change Management for Business Process Models VL - 32 ER - TY - CONF AU - Huma , Zille AU - Gerth , Christian AU - Engels, Gregor AU - Juwig, Oliver ID - 8475 T2 - Proceedings of the Forum at the CAiSE'12 Conference on Advanced Information Systems Engineering TI - A UML-based Rich Service Description Language for Automatic Service Discovery of Heterogeneous Service Partners VL - 855 ER - TY - CONF AU - Luckey , Markus AU - Mutz, Felix ID - 8476 T2 - Repository for Model-Driven Development (ReMoDD) TI - Modeling with Adapt Cases ER - TY - CONF AU - Geisen , Silke AU - Luckey , Markus AU - Engels, Gregor ID - 8477 T2 - Proceedings of 19. GI-WIVM Workshop: Qualitätsmanagement und Vorgehensmodelle TI - Ein Ansatz zur dynamischen Qualitätsmessung, -bewertung und Anpassung von Software Engineering Methoden ER - TY - CONF AU - Arifulina, Svetlana ID - 8478 T2 - Proceedings of the Doctoral Symposium of the 5th International Conference on Software Language Engineering 2012, Dresden, Germany (SLE (Doctoral Symposium)) TI - Towards a Framework for the Integration of Modeling Languages VL - 935 ER - TY - CONF AU - Güldali , Baris AU - Sauer, Stefan AU - Löhr, Perdita ID - 8479 IS - 2 T2 - Proceedings of the Workshop Modellbasierte und Modellgetriebene Softwaremodernisierung (MMSM 2012) TI - Entwicklung eines Softwarewerkzeugs für die modellgetriebene Migration betrieblicher Informationssysteme VL - 32 ER - TY - CONF AU - Mussbacher , Gunter AU - Alam , Omar AU - Alhaj , Mohammed AU - Ali , Shaukat AU - Amálio , Nuno AU - Barn , Balbir AU - Bræk , Rolv AU - Clark , Tony AU - Combemale , Benoit AU - Cysneiros , Luiz Marcio AU - Fatima , Urooj AU - France , Robert AU - Georg , Geri AU - Horkoff , Jennifer AU - Kienzle , Jörg AU - Leite , Julio Cesar AU - Lethbridge , Timothy C. AU - Luckey , Markus AU - Moreira , Ana AU - Mutz , Felix AU - A. Oliveira, A. Padua AU - C. Petriu , Dorina AU - Schöttle, Matthias AU - Troup, Lucy AU - Werneck, Vera M. B. ID - 8480 T2 - Proceedings of the Workshop about Comparing Modeling Approaches 2012 (@MODELS 2012) TI - Assessing composition in modeling approaches ER - TY - CONF AU - Luckey , Markus AU - Thanos , Christian AU - Gerth, Christian AU - Engels, Gregor ID - 8483 T2 - Proceedings of 1st International Workshop on EVALUATION for SELF-ADAPTIVE and SELF-ORGANIZING SYSTEMS at SASO'12 TI - Multi-Staged Quality Assurance for Self-Adaptive Systems ER - TY - CONF AU - Geisen, Silke ID - 8484 T2 - Proceedings of Software Engineering 2012 (SE 2012) - Doktorandensymposium TI - Ein Ansatz zur Anpassung von Software Engineering Methoden im laufenden Projekt VL - Report 01/12 ER - TY - CONF AU - Liebendörfer, Michael AU - Hochmuth, Reinhard ID - 8548 T2 - Beiträge zum Mathematikunterricht 2012 : Vorträge auf der 46. Tagung für Didaktik der Mathematik TI - Mathematikinteresse im 1. Studiensemester VL - 1 ER - TY - CONF AU - Biehler, Rolf AU - Hoppenbrock, Axel AU - Klemm, Juliane AU - Liebendörfer, Michael AU - Wassong, Thomas ID - 8552 T2 - CETL-MSOR Conference 2011 TI - Training of student teaching assistants and e-learning via math-bridge – Two projects at the German Centre for Higher Mathematics Education ER - TY - JOUR AB - We consider the space of complete rank two collineations. Starting from its description as a limit of GIT-quotients of a Grassmanian G(2, n) by a certain {\textbackslash}documentclass\{article\}{\textbackslash}usepackage\{amssymb\}{\textbackslash}begin\{document\}{\textbackslash}pagestyle\{empty\}\${\textbackslash}mathbb \{C\}{\textasciicircum}*\${\textbackslash}end\{document\}-action, we determine the Cox ring by means of toric ambient modifications. AU - Hausen, Jürgen AU - Liebendörfer, Michael ID - 8556 IS - 8-9 JF - Mathematische Nachrichten SN - 1522-2616 TI - The Cox ring of the space of complete rank two collineations VL - 285 ER - TY - CHAP AU - Beutner, Marc AU - Kremer, H.-Hugo AU - Zoyke, A ED - Kremer, H.-H ED - Beutner, M ED - Zoyke, A ID - 9587 T2 - Individuelle Förderung und berufliche Orientierung im berufsschulischen Übergangssystem. Ergebnisse aus dem Forschungs- und Entwicklungsprojekt InLab TI - Vorstellung des Modellprojekts InLab ER - TY - CHAP AU - Beutner, Marc AU - Frehe, Petra AU - Gebbe, M AU - Gockel, C AU - Kremer, H.-Hugo AU - Zoyke, A ED - Kremer, H.-H ED - Beutner, M ED - Zoyke, A ID - 9588 T2 - Individuelle Förderung und berufliche Orientierung im berufsschulischen Übergangssystem. Ergebnisse aus dem Forschungs- und Entwicklungsprojekt InLab TI - Vorstellung von vier Instrumenten zur Individuellen Förderung ER - TY - CHAP AU - Strauß, Sara ID - 9670 T2 - anglistik & englischunterricht TI - Victorian Values in Nineteenth- and Twenty-First-Century Advertising and Consumer Practices ER - TY - CHAP AU - Strauß, Sara ED - Gymnich, Marion ID - 9699 T2 - Who’s afraid of...? Facets of Fear in Anglophone Literature and Film TI - Facets of Children’s Fears in Twentieth- and Twenty-First-Century Stream-of-Consciousness Fiction ER - TY - CHAP AU - Strauß, Sara ED - Gymnich, Marion ED - Lichterfeld, Imke ID - 9700 T2 - A Hundred Years of The Secret Garden – Frances Hodgson Burnett’s Children’s Classic Revisited TI - Constructions of ‘Otherness’ in Frances Hodgson Burnett’s The Secret Garden ER - TY - GEN ED - Strauß, Sara ID - 9701 IS - 2 T2 - Critical Engagements: A Journal of Criticism and Theory: Special Section: Eva Figes TI - The Persistence of Modernism in Light VL - 5 ER - TY - GEN AB - Interview 11 Oct. 2012 AU - Flotmann, Christina ID - 9733 TI - Der Zauber Magischer Welten ER - TY - JOUR AB - A piezoelectric energy harvester is an electromechanical device that converts ambient mechanical vibration into electric power. Most existing vibration energy harvesting devices operate effectively at a single frequency only, dictated by the design of the device. This frequency must match the frequency of the host structure vibration. However, real world structural vibrations rarely have a specific constant frequency. Therefore, piezoelectric harvesters that generate usable power across a range of exciting frequencies are required to make this technology commercially viable. Currently known harvester tuning techniques have many limitations, in particular they miss the ability to work during harvester operation and most often cannot perform a precise tuning. This paper describes the design and testing of a vibration energy harvester with tunable resonance frequency, wherein the tuning is accomplished by changing the attraction force between two permanent magnets by adjusting the distance between the magnets. This tuning technique allows the natural frequency to be manipulated before and during operation of the harvester. Furthermore the paper presents a physical description of the frequency tuning effect. The experimental results achieved with a piezoelectric bimorph fit the calculated results very well. The calculation and experimental results show that using this tuning technique the natural frequency of the harvester can be varied efficiently within a wide range: in the test setup, the natural frequency of the piezoelectric bimorph could be increased by more than 70\%. AU - Al-Ashtari, Waleed AU - Hunstig, Matthias AU - Hemsel, Tobias AU - Sextro, Walter ID - 9781 IS - 3 JF - Smart Materials and Structures TI - Frequency tuning of piezoelectric energy harvesters by magnetic force VL - 21 ER - TY - JOUR AB - Piezoelectric structures are nowadays used in many different applications. A better understanding of the influence of material properties and geometrical design on the performance of these structures helps to develop piezoelectric structures specifically designed for their application. Different equivalent circuits have been introduced in the literature to investigate the behaviour of piezoelectric transducers. The model parameters are usually determined from measurements covering the characteristic frequencies of the piezoelectric transducer. This article introduces an analytical technique for calculating the mechanical and electrical equivalent system parameters and characteristic frequencies based on material properties and geometry for a cantilever bimorph structure. The model is validated by measurements using a cantilever bimorph and fits the experimental results better than previous models. The model gives a full set of piezoelectric transducer parameters and is therefore well suited for further theoretical investigations of piezoelectric transducers for different applications. The results also show that even small manufacturing tolerances have a considerable effect on the system parameters and characteristic frequencies. This might lead to intolerable deviations, especially in dynamic applications and should be avoided by careful design and production. AU - Al-Ashtari, Waleed AU - Hunstig, Matthias AU - Hemsel, Tobias AU - Sextro, Walter ID - 9782 IS - 1 JF - Journal of Intelligent Material Systems and Structures TI - Analytical determination of characteristic frequencies and equivalent circuit parameters of a piezoelectric bimorph VL - 23 ER - TY - CONF AB - To optimize the ultrasound irradiation for cavitation based ultrasound applications like sonochemistry or ultrasound cleaning, the correlation between cavitation intensity and the resulting effect on the process is of interest. Furthermore, changing conditions like temperature and pressure result in varying acoustic properties of the liquid. That might necessitate an adaption of the ultrasound irradiation. To detect such changes during operation, process monitoring is desired. Labor intensive processes, that might be carried out for several hours, also require process monitoring to increase their reliability by detection of changes or malfunctions during operation. In some applications cavitation detection and monitoring can be achieved by the application of sensors in the sound field. Though the application of sensors is possible, this necessitates modifications on the system and the sensor might disturb the sound field. In other applications harsh, process conditions prohibit the application of sensors in the sound field. Therefore alternative techniques for cavitation detection and monitoring are desired. The applicability of an external microphone and a self-sensing ultrasound transducer for cavitation detection were experimentally investigated. Both methods were found to be suitable and easily applicable. AU - Bornmann, Peter AU - Hemsel, Tobias AU - Sextro, Walter AU - Maeda, Takafumi AU - Morita, Takeshi ID - 9783 KW - cavitation KW - chemical reactors KW - microphones KW - process monitoring KW - reliability KW - ultrasonic applications KW - ultrasonic waves KW - acoustic properties KW - cavitation based ultrasound applications KW - cavitation intensity KW - change detection reliability KW - external microphone KW - malfunction detection reliability KW - nonperturbing cavitation detection KW - nonperturbing cavitation monitoring KW - process monitoring KW - self-sensing ultrasound transducer KW - sonochemical reactors KW - sonochemistry KW - ultrasound cleaning KW - ultrasound irradiation KW - Acoustics KW - Liquids KW - Monitoring KW - Sensors KW - Sonar equipment KW - Transducers KW - Ultrasonic imaging SN - 1948-5719 T2 - Ultrasonics Symposium (IUS), 2012 IEEE International TI - Non-perturbing cavitation detection / monitoring in sonochemical reactors ER - TY - CONF AB - Piezoelectric inertia motors use the inertia of a body to drive it by means of a friction contact in a series of small steps. These motors can operate in ``stick-slip'' or ``slip-slip'' mode, with the fundamental frequency of the driving signal ranging from several Hertz to more than 100 kHz. To predict the motor characteristics, a Coulomb friction model is sufficient in many cases, but numerical simulation requires microscopic time steps. This contribution proposes a much faster simulation technique using one evaluation per period of the excitation signal. The proposed technique produces results very close to those of timestep simulation for ultrasonics inertia motors and allows direct determination of the steady-state velocity of an inertia motor from the motion profile of the driving part. Thus it is a useful simulation technique which can be applied in both analysis and design of inertia motors, especially for parameter studies and optimisation. AU - Hunstig, Matthias AU - Hemsel, Tobias AU - Sextro, Walter ID - 9784 KW - friction KW - ultrasonic motors KW - Coulomb friction model KW - efficient simulation technique KW - friction contact KW - high-frequency piezoelectric inertia motor KW - motor characteristics prediction KW - numerical simulation KW - slip-slip mode KW - stick-slip mode KW - time-step simulation KW - ultrasonic inertia motor KW - Acceleration KW - Acoustics KW - Actuators KW - Computational modeling KW - Friction KW - Numerical models KW - Steady-state SN - 1948-5719 T2 - Ultrasonics Symposium (IUS), 2012 IEEE International TI - An efficient simulation technique for high-frequency piezoelectric inertia motors ER - TY - CONF AB - Hydrothermal method enables to synthesize high quality piezoelectric materials. To shorten the reaction time and to get higher quality materials, we propose an ultrasonic irradiation to the solution during the hydrothermal method. We named it ultrasonic assisted hydrothermal method (UAHTM). We have synthesized lead-free piezoelectric material and PZT thin film and the effect of UAHTM have been confirmed. In this study, we tried to improve UAHTM. First, to generate powerful and stable ultrasonic irradiation at high temperature on UAHTM, we developed a new transducer using LiNbO3 single crystal. Second, to prevent contamination to the materials, A Teflon cover on the tip of transducer was attached. AU - Isobe, Gaku AU - Ageba, Ryo AU - Maeda, Takafumi AU - Bornmann, Peter AU - Hemsel, Tobias AU - Morita, Takeshi ED - B. J. Linde, Bogumil ED - Paczkowski, Jacek ED - Ponikwicki, Nikodem ID - 9785 IS - 1 KW - contamination KW - lead compounds KW - piezoelectric materials KW - piezoelectric thin films KW - piezoelectric transducers KW - ultrasonic effects T2 - AIP Conference Proceedings TI - Synthesis of piezoelectric materials by ultrasonic assisted hydrothermal method VL - 1433 ER - TY - JOUR AB - Self-optimizing mechatronic systems are a new class of technical systems. On the one hand, new challenges regarding dependability arise from their additional complexity and adaptivity. On the other hand, their abilities enable new concepts and methods to improve the dependability of mechatronic systems. This paper introduces a multi-level dependability concept for selfoptimizing mechatronic systems and shows how probabilistic planning can be used to improve the availability and reliability of systems in the operating phase. The general idea to improve the availability of autonomous systems by applying probabilistic planning methods to avoid energy shortages is exemplified on the example of an innovative railway vehicle. AU - Klöpper, Benjamin AU - Sondermann-Wölke, Christoph AU - Romaus, Christoph ID - 9786 IS - 1 JF - Journal of Robotics and Mechatronics KW - self-optimizing systems KW - dependability KW - probabilistic planning KW - energy management TI - Probabilistic Planning for Predictive Condition Monitoring and Adaptation Within the Self-Optimizing Energy Management of an Autonomous Railway Vehicle VL - 24 ER - TY - CONF AU - Kohl, Sergej AU - Sextro, Walter AU - Zuber, Armin ID - 9787 T2 - 8. Tag des Fahrwerks, Aachen, 2012 TI - Benteler Vehicle Dynamics -- Fahrdynamikentwicklung basierend auf einer neuen Auslegungstheorie ER - TY - CONF AB - A hydrothermal method utilizes a crystallization process in the solution so that the pure and high-quality powders can be realized. Sintering from the hydrothermal KNbO3 and NaNbO3 powders, a high-dense lead-free piezoelectric (K,Na)NbO3 ceramics could be obtained (density: 98.8\%). Concerning about the g33 constant, high value as large as commercial PZT ceramics was measured. Therefore, the hydrothermal (K,Na)NbO3 ceramics is usable for the sensors and the energy harvesting devices. To demonstrate the (K,Na)NbO3 ceramics, a hydrophone sensor was fabricated and evaluated. AU - Maeda, Takafumi AU - Bornmann, Peter AU - Hemsel, Tobias AU - Morita, Takeshi ID - 9788 KW - crystallisation KW - hydrophones KW - piezoceramics KW - potassium compounds KW - powder technology KW - powders KW - sensors KW - sintering KW - sodium compounds KW - (K0.48Na0.52)NbO3 KW - KNbO3 powder KW - NaNbO3 powder KW - crystallization KW - energy harvesting devices KW - g33 constant KW - hydrophone sensor KW - hydrothermal lead-free (K0.48Na0.52)NbO3 ceramics KW - hydrothermal method KW - piezoelectric applications KW - sintering KW - Materials KW - Transducers SN - 1948-5719 T2 - Ultrasonics Symposium (IUS), 2012 IEEE International TI - Piezoelectric applications of hydrothermal lead-free (K0.48Na0.52)NbO3 ceramics ER - TY - JOUR AB - [$Li_x(Na_0.52K_0.48)_1-x]NbO_3 (0 \leq x \leq 0.091)$ ceramics were synthesized using hydrothermal powders and the lithium doping content was controlled to optimize their piezoelectric properties. The raw KNbO$_3$ and NaNbO$_3$ powders were obtained separately by a hydrothermal method and LiNbO$_3$ powders were prepared by milling a commercial LiNbO$_3$ single crystal. These powders were mixed with ethanol at a molar ratio LiNbO$_3$: ($Na_0.52K_0.48$)NbO$_3 = x : 1-x$. The synthesized powders were sintered at 1060--1120 $\,^{\circ}$C for 2 h. We succeeded in obtaining highly dense [$Li_x(Na_0.52K_0.48)_1-x]NbO_3$ ceramics using hydrothermal powder. The X-ray diffraction patterns revealed that the crystal phase changed from orthorhombic to tetragonal at around x = 0.06. At this morphotropic phase boundary (MPB), the c/a ratio changed from 1.016 to 1.024 and the highest piezoelectric constant was obtained with the chemical component of [$Li_x(Na_0.52K_0.48)_1-x]NbO_3$. The obtained piezoelectric properties were as follows: $k_33 = 0.51, \epsilon 33^T/ \epsilon _0 = 836$ , $c_33^E = 46$ GPa, $d_33 = 203$ pC/N, and $T_c = 482 $\,^{\circ}$C$. AU - Maeda, Takafumi AU - Hemsel, Tobias AU - Morita, Takeshi ID - 9789 JF - Japanese Journal of Applied Physics TI - Piezoelectric Properties of Li-Doped (K0.48Na0.52)NbO3 Ceramics Synthesized Using Hydrothermally-Derived KNbO3 and NaNbO3 Fine Powders VL - 51 ER - TY - CONF AB - The rapid development of communication and information technology opens up fascinating perspectives, which go far beyond the state of the art in mechatronics: mechatronic systems with inherent partial intelligence. These so called self-optimizing systems adapt their objectives and behavior autonomously and flexibly to changing operating conditions. On the one hand, securing the dependability of such systems is challenging due to their complexity and non-deterministic behavior. On the other hand, self-optimization can be used to increase the dependability of the system during its operation. However, it has to be ensured, that the self-optimization works dependable itself. To cope with these challenges, the multi-level dependability concept was developed. It enables predictive condition monitoring, influences the objectives of the system and determines suitable means to improve the system's dependability during its operation. In this contribution we introduce a procedure for the conceptual design of an advanced condition monitoring based on the system's principle solution. The principle solution describes the principal operation mode of the system and its desired behavior. It is modeled using the specification technique for the domain-spanning description of the principle solution of a self-optimizing system and consists of a coherent system of eight partial models (e.g. requirements, active structure, system of objectives, behavior, etc.). The partial models are analyzed separately in order to derive the components of the multi-level dependability concept. In particular, the reliability analysis of the partial model active structure is performed to identify the system elements to be monitored and parameters to be measured. The principle solution is extended accordingly: e.g. with system elements required for the realization of the dependability concept. The advantages of the method are shown on the self-optimizing guidance module of a railroad vehicle. AU - Sondermann-Wölke , Christoph AU - Meyer, Tobias AU - Dorociak, Rafal AU - Gausemeier, Jürgen AU - Sextro, Walter ID - 9791 KW - Mechatronic Systems KW - Principle Solution KW - Condition Monitoring KW - Conceptual Design T2 - Proceedings of the 11th International Probabilistic Safety Assessment and Management Conference (PSAM11) and The Annual European Safety and Reliability Conference (ESREL2012) TI - Conceptual Design of Advanced Condition Monitoring for a Self-Optimizing System based on its Principle Solution ER - TY - JOUR AB - Piezoelectric inertia motors, also known as ``stick-slip-drives'', use the inertia of a body to drive it by means of a friction contact in small steps. While these steps normally involve stiction and sliding, the motors can also operate in ``slip-slip'' mode without any phase of static friction. In this contribution, a one degree of freedom model of an inertia motor driven by an ideal actuator is analysed. Start-up and constant velocity operation of the motor are investigated and appropriate quantities to compare ``stick-slip'' and ``slip-slip'' operation are determined. Different aspects such as velocity, uniformity of motion, load capacity, robustness, efficiency, and wear are considered. The analysis allows both modes to be applied advantageously in different applications and can widen the field of application of piezoelectric inertia motors. Motor designers are enabled to choose the appropriate mode of operation and the best drive parameters for their individual applications. AU - Hunstig, Matthias AU - Hemsel, Tobias AU - Sextro, Walter ID - 9806 JF - ACTUATOR 2012 Conference Proceedings KW - Piezoelectric Inertia Motors KW - Drive Signals KW - Stick-slip KW - Slip-slip TI - Analysis of different operation modes for inertia motors ER - TY - JOUR AB - Aiming to diminish the reflection losses of glass covered light harvesting devices, the optical reflectivity of nanostructured glass surfaces is studied theoretically and experimentally. The work is inspired by the nanoscale roughness of insect eyes, which is tried to be replicated on a technical glass surface. To this end, the reflectivity of glass surfaces with topographies represented by linear, parabolic and Fermishaped glass/air fill factor profiles is calculated for normal incidence. It is shown that using the latter ones, an almost complete suppression of reflections can be achieved. A simple, self-organization technique to create such Fermi-shaped filling factor profiles in glass experimentally is also presented. AU - Achtelik, J. AU - Sievers, W. AU - Lindner, Jörg ID - 4095 IS - 9 JF - Materials Science and Engineering: B SN - 0921-5107 TI - Biomimetic approaches to create anti-reflection glass surfaces for solar cells using self-organizing techniques VL - 178 ER - TY - JOUR AB - We report on the molecular beam epitaxy growth of cubic GaN on 3C–SiC (001) nanostructures. Transmission electron microscopy (TEM) studies show phase-pure cubic GaN crystals with a low defect density on top of the post shaped 3C–SiC nanostructures and GaN grown on their sidewalls, which is dominated by {111} planar defects. The nanostructures, aligned parallel and perpendicular to the [110] directions of the substrate, are located in anti-phase domains of the 3C–SiC/Si (001) substrate. These anti-phase domains strongly influence the optimum growth of GaN layers in these regions. TEM measurements demonstrate a different stacking fault density in the cubic GaN epilayer in these areas. AU - Kemper, R.M. AU - Hiller, L. AU - Stauden, T. AU - Pezoldt, J. AU - Duschik, K. AU - Niendorf, T. AU - Maier, H.J. AU - Meertens, D. AU - Tillmann, K. AU - As, D.J. AU - Lindner, Jörg ID - 4104 JF - Journal of Crystal Growth SN - 0022-0248 TI - Growth of cubic GaN on 3C–SiC/Si (001) nanostructures VL - 378 ER - TY - JOUR AB - Two methods to create biomimetic anti-reflection nanostructures in ordinary glass microscope object slides are presented. One technique is based on a nanosphere lithography process combined with physical vapour deposition of nickel and reactive ion etching (RIE). The other uses plasma induced dewetting of a smooth nickel surface. The amount of reflected light was measured and a method to simulate the reflectivity from an atomic force microscopy (AFM) topography scan of the glass surface is presented. The reflectivity for visible light at normal incidence was reduced to 20-50 % of the original value with both methods and the simulation gives results in good agreement to the measurement. AU - Achtelik, Jörn AU - Kemper, Ricarda M. AU - Sievers, Werner AU - Lindner, Jörg ID - 4114 JF - MRS Proceedings SN - 1946-4274 TI - Self-Organized Nanostructure Formation for Anti-Reflection Glass Surfaces VL - 1389 ER - TY - CONF AU - Brodehl, Christoph AU - Greulich-Weber, Siegmund AU - Lindner, Jörg ID - 4115 TI - Gyrotropic Metamaterials ER - TY - JOUR AB - We report an anisotropic formation of defects in cubic GaN grown on nano-patterned 3C-SiC/Si (001) by molecular beam epitaxy. Nano-patterning of 3C-SiC/Si (001) is achieved by nanosphere lithography and a reactive ion etching process. Atomic force microscopy and scanning electron microscopy show that the selectivearea- grown cubic GaN nucleates in two structurally different domains, which most probably originate from the substrate. In adjacent domains the formation of defects, especially hexagonal inclusions, is different and leads to two different surface morphologies. The dominant phase within these domains was measured by electron backscatter diffraction. Optical properties were investigated by micro-photoluminescence and cathodoluminescence spectroscopy. AU - Kemper, R. M. AU - Häberlen, M. AU - Schupp, T. AU - Weinl, M. AU - Bürger, M. AU - Ruth, M. AU - Meier, Cedrik AU - Niendorf, T. AU - Maier, H. J. AU - Lischka, K. AU - As, D. J. AU - Lindner, Jörg ID - 4131 IS - 3-4 JF - physica status solidi (c) SN - 1862-6351 TI - Formation of defects in cubic GaN grown on nano-patterned 3C-SiC (001) VL - 9 ER - TY - CONF AU - Kemper, R.M. AU - Hiller, L. AU - Stauden, T. AU - Pezoldt, J. AU - Meertens, D. AU - Luysberg, M. AU - Tillmann, K. AU - Riedl, Thomas AU - As, Donald AU - Lindner, Jörg ID - 4133 TI - TEM investigation of GaN thin films grown on nanostructured 3C-SiC/Si(001) substrates ER - TY - CONF AU - Lindner, Jörg ID - 4134 TI - Nanosphere Lithography: State-of-the-art and Future Directions ER - TY - CONF AU - Pauly, Johannes AU - Lindner, Jörg ID - 4135 TI - TEM Characterization of Nickel Nanodot Arrays on Silicon formed by Nanosphere Lithography ER - TY - CONF AU - Lindner, Jörg ID - 4138 TI - Nanokugellithographie: Grundlagen und Anwendungen ER - TY - CONF AU - Lindner, Jörg ID - 4139 TI - Nanolithographie von Oberflächen für das Wachstum optoelektronischer Strukturen ER - TY - JOUR AU - Chen, Xianzhong AU - Huang, Lingling AU - Mühlenbernd, Holger AU - Li, Guixin AU - Bai, Benfeng AU - Tan, Qiaofeng AU - Jin, Guofan AU - Qiu, Cheng-Wei AU - Zhang, Shuang AU - Zentgraf, Thomas ID - 43 JF - Nature Communications SN - 2041-1723 TI - Dual-polarity plasmonic metalens for visible light VL - 3 ER - TY - JOUR AU - Feneberg, Martin AU - Röppischer, Marcus AU - Cobet, Christoph AU - Esser, Norbert AU - Schörmann, Jörg AU - Schupp, Thorsten AU - As, Donat Josef AU - Hörich, Florian AU - Bläsing, Jürgen AU - Krost, Alois AU - Goldhahn, Rüdiger ID - 4333 IS - 15 JF - Physical Review B SN - 1098-0121 TI - Optical properties of cubic GaN from 1 to 20 eV VL - 85 ER - TY - CONF AB - The structural and vibrational properties of lithium niobate (LN) – lithium tantalate (LT) mixed crystals (LNT, LiNb1-xTaxO3) are investigated over the whole composition range by first-principles simulations. The crystal volume grows roughly linearly from LT to LN, whereby the lattice parameters a and c show minor deviations from the Vegard behavior between the end compounds, LiNbO3 and LiTaO3. Our calculations in the framework of the density functional theory show the TO1, TO2 and TO4-modes to become harder with increasing Nb concentration. TO3 becomes softer with increasing Nb content, instead. The frequency shifts of the zone center A1-TO phonon modes for crystals with different compositions are found to be as large as 30 cm-1. Raman spectroscopy, which is sensitive to the A1 modes, can be therefore employed to determine the crystal composition. AU - Sanna, Simone AU - Riefer, Arthur AU - Neufeld, Sergej AU - Schmidt, Wolf Gero AU - Berth, Gerhard AU - Widhalm, Alex AU - Zrenner, Artur ID - 4380 KW - Ferroelectrics KW - Vibrational properties KW - LiNbO3 KW - LiTaO3 KW - Mixed Crystals T2 - Proceedings of ISAF-ECAPD-PFM 2012 TI - Vibrational fingerprints of LiNbO3-LiTaO3 mixed crystals ER - TY - CHAP AB - Coherent physics and applications of exciton qubits in electric fi eld tunable quantum dot structures are our focus. Excitations with picosecond (ps) laser pulses result in qubit rotations. Using state projection by tunnelling the readout can be performed in quantitative way. As a function of electric fi eld induced detuning Ramsey fringes of a single exciton qubit can be observed and controlled for double pulse excitation. Therefore it is possible to demonstrate voltage controlled qubit manipulations within a wide range of pulse delays. Using fast electric signals, phase-locked to ps-laser pulses, the coherent control of an exciton qubit can be obtained by electric interaction. Such voltage controlled qubit manipulations seem to be essential for new types of optoelectronic quantum gates and novel applications in the fi eld of coherent optoelectronics. AU - Michaelis de Vasconcellos, Steffen AU - Gordon, Simon AU - Mantei, Dirk AU - Leier, Yves Alexander AU - Al-Hmoud, M. AU - Quiring, Wadim AU - Zrenner, Artur ED - Jahnke, Frank ID - 4381 KW - excitons KW - quantum bits KW - coherent manipulation KW - Ramsey interference KW - quantum gate SN - 9780857092328 0857092324 T2 - QUANTUM OPTICS WITH SEMICONDUCTOR NANOSTRUCTURES TI - Coherent optoelectronics with quantum dots ER - TY - CHAP AU - Becker, Jörg AU - Beverungen, Daniel AU - Knackstedt, Ralf ED - Granat Janusz Dolk, Daniel; ID - 5032 T2 - Modeling for Decision Support in Network-Based Services: The Application of Quantitative Modeling to Service Science TI - A Method for Selectively Designing Modeling Languages for Product-Service Systems ER - TY - CHAP AU - Becker, Jörg AU - Knackstedt, Ralf AU - Beverungen, Daniel AU - Dietrich, Hanns-Alexander AU - Breuker, Dominic AU - Peter Rauer, Hans ED - Böhmann, Tilo ED - Knackstedt, Ralf ED - Marco Leimeister, Jan ED - Nüttgens, Markus ED - Thomas, Oliver ID - 5034 SN - 978-3-8482-2109-7 T2 - Service Engineering --- Management TI - Ansätze zur methodischen Unterstützung der Konstruktion von Produktivitätsmodellen für die Data Envelopment Analysis --- Entwicklung eines Softwareprototypen zur Umsetzung und Evaluation ER - TY - CHAP AU - Beverungen, Daniel AU - Matzner, Martin AU - Müller, Oliver AU - Becker, Jörg ED - Barros, Alistair ED - Oberle, Daniel ID - 5035 SN - 978-1-4614-1864-1 T2 - Handbook of Service Description TI - Product-Service System Approaches ER - TY - GEN AU - Hegemann, Annika ID - 5051 TI - Besteuerung von Beteiligungsinvestitionen und Risikoempfindlichkeit – Wie wirkt die Abgeltungssteuer? VL - 140 ER - TY - GEN AU - Mehrmann, Annika AU - Schneider, Georg AU - Sureth-Sloane, Caren ID - 5055 TI - Asymmetric Taxation of Profits and Losses and Its Influence on Investment Timing: Paradoxical Effects of Tax Increases VL - 134 ER - TY - JOUR AU - Sloane, Peter F. E. AU - Sureth-Sloane, Caren ID - 5056 IS - 7-8 JF - Wirtschaft und Beruf TI - Mehr Theorie wagen. Betriebswirtschaftslehre nach Bologna oder Hochschulbildung im Wandel VL - 64 ER - TY - GEN AU - Sureth-Sloane, Caren ID - 5057 IS - 112 T2 - Frankfurter Allgemeine Zeitung TI - Analytisch und strukturiert denken lernen ER - TY - GEN AU - Sureth-Sloane, Caren ID - 5060 T2 - Frankfurter Allgemeine Zeitung TI - Studium nach Bologna: Theorie oder Praxis – ein Scheinwiderspruch? ER - TY - JOUR AU - Sureth-Sloane, Caren ID - 5063 IS - 7-8 JF - Wirtschaft und Beruf TI - Unternehmensführung und interkulturelle Hochschulbildung. Unternehmensführung in Europa - Interkulturelle Fragen VL - 64 ER - TY - CHAP AU - Sureth-Sloane, Caren ED - Burr, Wolfgang ED - Wagenhofer, Alfred ID - 5066 T2 - Der Verband der Hochschullehrer für Betriebswirtschaft, Geschichte des VHB und Geschichten zum VHB TI - Vorwort. Geschichte des VHB und der BWL: Rückblick und Einblicke ER - TY - GEN AU - Sureth-Sloane, Caren AU - zu Knyphausen-Aufseß, Dodo ID - 5069 IS - 276 T2 - Frankfurter Allgemeine Zeitung TI - Welcher BWLer ist ein guter Forscher? ER - TY - JOUR AU - Gilroy, Bernard Michael AU - Kruse, Daniel ID - 5116 IS - 3 JF - WiSt-Wirtschaftswissenschaftliches Studium TI - Die Prinzipal-Agent-Theorie als Erklärungsinstrumentarium von Korruption VL - 41 ER - TY - JOUR AU - Bodden, Eric AU - Lam, Patrick AU - Hendren, Laurie ID - 5183 IS - 2 JF - ACM Transactions on Programming Languages and Systems SN - 0164-0925 TI - Partially Evaluating Finite-State Runtime Monitors Ahead of Time VL - 34 ER - TY - JOUR AB - We study the predictive ability of individual analyst target price changes for post-event abnormal stock returns within each recommendation category. Although prior studies generally demonstrate the investment value of target prices, we find that target price changes do not cause abnormal returns within each recommendation level. Instead, contradictory analyst signals (e.g., strong buy reiterations with large target price decreases) neutralize each other, whereas confirmatory signals reinforce each other. Further, our analysis reveals that large target price downgrades can be explained by preceding stock price decreases. However, upgrades are not preceded by stock price increases, thereby demonstrating asymmetric analyst behavior when adjusting target prices to stock prices. Our results suggest that investors should treat recommendations with caution when they are issued with large contradictory target price changes. Thus, instead of blindly following a recommendation, investors might put more weight on the change in the corresponding target price and consider transaction costs. AU - Kanne, Stefan AU - Klobucnik, Jan AU - Kreutzmann, Daniel AU - Sievers, Sönke ID - 5193 IS - 4 JF - Financial Markets and Portfolio Management (VHB-JOURQUAL 3 Ranking C) KW - Analyst recommendation KW - Target price KW - Stock performance KW - Trading strategy TI - To buy or not to buy? The value of contradictory analyst signals VL - 26 ER - TY - JOUR AB - This study shows how venture capital investors can identify potential biases in multi-year management forecasts before an investment decision and derive significantly more accurate failure predictions. By advancing a cross-sectional projection method developed by prior research and using firm-specific information in financial statements and business plans, we derive benchmarks for management revenue forecasts. With these benchmarks, we estimate forecast errors as an a priori measure of biased expectations. Using this measure for our proprietary dataset on venture-backed start-ups in Germany, we find evidence of substantial upward forecast biases. We uncover that firms with large forecast errors fail significantly more often than do less biased entrepreneurs in years following the investment. Overall, our results highlight the implications of excessive optimism and overconfidence in entrepreneurial environments and emphasize the relevance of accounting information and business plans for venture capital investment decisions. AU - Mokwa, Christopher Frederik AU - Sievers, Sönke ID - 5196 JF - SSRN Electronic Journal KW - Management forecast biases KW - cross-sectional projection models KW - venture-backed start-ups KW - failure prediction KW - overoptimism KW - overconfidence TI - The Relevance of Biases in Management Forecasts for Failure Prediction in Venture Capital Investments ER - TY - JOUR AB - This study provides evidence of significant biases in multi-year management forecasts by analyzing a proprietary dataset on venture-backed start-ups in Germany. We find that revenues and expenses are highly overestimated in each of the investigated one- to five-year-ahead planning periods. Furthermore, entrepreneurs underestimate one-year-ahead profit forecasts but clearly overestimate their profit forecasts for all longer-term forecast horizons. Additional analyses reveal that teams with prior management experience issue even more overestimated forecasts and misrepresent their forward-looking information. In contrast, greater asset verifiability and corporate lead investors are associated with lower levels of forecast errors. All key results hold if bias is either measured by traditionally comparing forecasts to ex-post realizations or by using a cross-sectional projection approach based on historical accounting data developed by prior research. AU - Mokwa, Christopher AU - Sievers, Sönke ID - 5198 JF - SSRN Electronic Journal KW - Management forecasts KW - Forecasting biases KW - Venture-backed start-ups KW - Projection methods TI - Biases in Management Forecasts of Venture-Backed Start-Ups: Evidence from Internal Due Diligence Documents of VC Investors ER - TY - CHAP AU - Schmitz, Hendrik AU - Eibich, P. AU - Ziebarth, N.R. ID - 5242 T2 - DIW Economic Bulletin TI - Add-On Premiums Increase Price Transparency: More Policy Holders Switch Health Plans VL - 2 ER - TY - JOUR AU - Schmitz, Hendrik AU - Augurzky, B. AU - Beivers, A. ID - 5243 JF - Krankenhaus-Report 2012 TI - Regionale Unterschiede in der stationären Versorgung: Das ländliche Krankenhaus im Fokus ER - TY - JOUR AU - Baum, M AU - Gsell, L AU - Kabst, Rüdiger ID - 5494 IS - 3 JF - Die Betriebswirtschaft (ZfB). TI - Determinanten des Employer Branding in deutschen Unternehmen: Ein neoinstitutionalistischer Erklärungsansatz. VL - 72 ER - TY - JOUR AU - Baum, M AU - Kabst, Rüdiger ID - 5496 JF - Zeitschrift für Betriebswirtschaft (ZfB). TI - Die Wirkung von informellen und internetbasierten Rekrutierungskanälen auf den Rekrutierungserfolg: Eine empirische Analyse in kleinen und mittleren Unternehmen. VL - 3 ER - TY - JOUR AU - Maekelburger, B AU - Schwens, C AU - Kabst, Rüdiger ID - 5497 IS - 5 JF - Journal of International Business Studies (JIBS). TI - Asset Specificity and Foreign Market Entry Mode Choice of Small and Medium-Sized Enterprises: The Moderating Influence of Knowledge Safeguards and Institutional Safeguards. VL - 42 ER - TY - JOUR AU - Eberz, L M AU - Baum, M AU - Kabst, Rüdiger ID - 5498 IS - 1 JF - Zeitschrift für Personalforschung (ZfP). TI - Der Einfluss von Rekrutiererverhaltensweisen auf den Bewerber: Ein mediierter Prozess. VL - 26 ER - TY - JOUR AU - Wehner, M C AU - Kabst, Rüdiger AU - Meifert, M AU - Cunz, L M ID - 5508 IS - 9 JF - Zeitschrift für Betriebswirtschaft (ZfB). TI - Der Personalverantwortliche als strategischer Partner: Persönliche Einstellung oder subjektive Norm? VL - 82 ER - TY - JOUR AU - Strohmeier, S AU - Kabst, Rüdiger ID - 5510 IS - 3 JF - International Journal of Business Information Systems (IJBIS). TI - Evaluating Major Human Resource Information Systems Design Characteristics: An Empirical Analysis. VL - 9 ER - TY - JOUR AU - Frese, M AU - Bausch, A AU - Schmidt, P AU - Rauch, A AU - Kabst, Rüdiger ID - 5512 IS - 1 JF - Foundations and Trends in Entrepreneurship. TI - Evidence-based entrepreneurship (EBE): Cumulative science, action principles, and bridging the gap between science and practice. VL - 8 ER - TY - JOUR AU - Wehner, M C AU - Giardini, A AU - Kabst, Rüdiger ID - 5515 IS - 4 JF - Human Resource Management. TI - Graduates’ Reactions to Recruitment Process Outsourcing: A Scenario-Based Study. VL - 51 ER - TY - JOUR AU - Eiche, J AU - Schwens, C AU - Kabst, Rüdiger ID - 5516 IS - 3 JF - Zeitschrift für Betriebswirtschaft (ZfB). TI - Greenfield Investment versus Akquisition: Der moderierende Einfluss wahrgenommener institutioneller Unsicherheit bei der Internationalisierung von KMU. VL - 82 ER - TY - JOUR AU - Isidor, R AU - Schwens, C AU - Kabst, Rüdiger AU - Hornung, F ID - 5518 IS - 5 JF - Zeitschrift für Betriebswirtschaft (ZfB). TI - Internationaler Joint Venture Erfolg: Eine Meta-Analyse. VL - 82 ER - TY - JOUR AU - Steinmetz, Holger AU - Isidor, R AU - Bäuerle, N ID - 5519 IS - 1 JF - Survey Research Methods TI - Testing the Circular Structure of Human Values: A Meta-Analytical Structural Equation Modelling Approach. VL - 6 ER -