TY - JOUR A1 - Jäger, Christoph G. A1 - Diehl, S. A1 - Schmidt, G. M. T1 - Influence of water-column depth and mixing intensity on phytoplankton biomass and functional community composition JF - Limnology and Oceanography N2 - We independently manipulated mixing intensity (strong artificial mixing vs. background turbulence) and water‐column depth (2 m, 4 m, 8 m, and 12 m) in order to explore their separate and combined effects in a field enclosure experiment. To accentuate the vertical light gradient, enclosures had black walls, resulting in a euphotic depth of only 3.7 m. All enclosures were placed in a well‐mixed water bath to equalize temperature across treatments. Phytoplankton responded to an initial phosphorus pulse with a transient increase in biomass, which was highest in the shallowest, least light‐limited water columns where dissolved mineral phosphorus subsequently became strongly limiting. As a consequence, the depth‐averaged mineral phosphorus concentration increased and the seston carbon (C) : phosphorous (P) ratio decreased with increasing water‐column depth. Low turbulence enclosures became quickly dominated by motile taxa (flagellates) in the upper water column, whereas mixed enclosures became gradually dominated by pennate diatoms, which resulted in higher average sedimentation rates in the mixed enclosures over the 35‐d experimental period. Low turbulence enclosures showed pronounced vertical structure in water columns >4 m, where diversity was higher than in mixed enclosures, suggesting vertical niche partitioning. This interpretation is supported by a primary production assay, where phytoplankton originating from different water depths in low‐turbulence treatments had the relatively highest primary productivity when incubated at their respective depths of origin. KW - aquatic ecology Y1 - 2008 UR - https://doi.org/10.4319/lo.2008.53.6.2361 VL - 53 IS - 6 SP - 2361 EP - 2373 ER - TY - JOUR A1 - Zobel, M. A1 - Denzler, J. A1 - Heigl, B. A1 - Nöth, E. A1 - Paulus, D. A1 - Schmidt, Jochen A1 - Stemmer, G. T1 - MOBSY: Integration of vision and dialogue in service robots JF - Machine Vision and Applications N2 - This contribution introduces MOBSY, a fully integrated, autonomous mobile service robot system. It acts as an automatic dialogue-based receptionist for visitors to our institute. MOBSY incorporates many techniques from different research areas into one working stand-alone system. The techniques involved range from computer vision over speech understanding to classical robotics. Along with the two main aspects of vision and speech, we also focus on the integration aspect, both on the methodological and on the technical level. We describe the task and the techniques involved. Finally, we discuss the experiences that we gained with MOBSY during a live performance at our institute. KW - Service robots KW - Computer vision KW - Speech understanding and dialogue KW - Integrated System Y1 - 2003 ER - TY - JOUR A1 - Zobel, M. A1 - Denzler, J. A1 - Heigl, B. A1 - Nöth, E. A1 - Paulus, D. A1 - Schmidt, Jochen A1 - Stemmer, G. T1 - Demonstration von Bildverarbeitung und Sprachverstehen in der Dienstleistungsrobotik JF - Autonome Mobile Systeme N2 - Die typischerweise gewünschten Einsatzgebiete für Dienstleistungsroboter, z. B. Krankenhäuser oder Seniorenheime, stellen sehr hohe Anforderungen an die Mensch-Maschine-Schnittstelle. Diese Erfordernisse gehen im Allgemeinen über die Möglichkeiten der Standardsensoren, wie Ultraschalloder Infrarotsensoren, hinaus. Es müssen daher ergänzende Verfahren zum Einsatz kommen. Aus der Sicht der Mustererkennung sind die Nutzung des Rechnersehens und des natürlichsprachlichen Dialogs von besonderem Interesse. Dieser Beitrag stellt das mobile System MOBS Y vor. MOBS Y ist ein vollkommen integrierter autonomer mobiler Dienstleistungsroboter. Er dient als ein automatischer dialogbasierter Empfangsservice für Besucher unseres Instituts. MOBSY vereinigt vielfältige Methoden aus unterschiedlichsten Forschungsgebieten in einem eigenständigen System. Die zum Einsatz kommenden Methoden aus dem Bereich der Bildverarbeitung reichen dabei von Objektklassifikation über visuelle Selbstlokalisierung und Rekalibrierung bis hin zu multiokularer Objektverfolgung. Die Dialogkomponente umfasst Methoden der Spracherkennung, des Sprachverstehens und die Generierung von Antworten. Im Beitrag werden die zu erfüllende Aufgabe und die einzelnen Verfahren dargestellt. KW - Dienstleistungsroboter KW - multiokulare Objektverfolgung KW - Spracherkennung KW - Sensorik bei Robotern Y1 - 2001 ER - TY - CHAP A1 - Zobel, M. A1 - Denzler, J. A1 - Heigl, B. A1 - Nöth, E. A1 - Paulus, D. A1 - Schmidt, Jochen A1 - Stemmer, G. T1 - MOBSY: Integration of vision and dialogue in service robots T2 - Computer Vision Systems, Proceedings Second International Workshop, ICVS 2001, Vancouver, Canada N2 - MOBSY is a fully integrated autonomous mobile service robot system. It acts as an automatic dialogue based receptionist for visitors of our institute. MOBSY incorporates many techniques from different research areas into one working stand-alone system. Especially the computer vision and dialogue aspects are of main interest from the pattern recognition’s point of view. To summarize shortly, the involved techniques range from object classification over visual self-localization and recalibration to object tracking with multiple cameras. A dialogue component has to deal with speech recognition, understanding and answer generation. Further techniques needed are navigation, obstacle avoidance, and mechanisms to provide fault tolerant behavior. This contribution introduces our mobile system MOBSY. Among the main aspects vision and speech, we focus also on the integration aspect, both on the methodological and on the technical level. We describe the task and the involved techniques. Finally, we discuss the experiences that we gained with MOBSY during a live performance at the 25th anniversary of our institute KW - Speech recognition KW - Obstacle Avoidance  KW - Humanoid Robot  KW - Service Robot Y1 - 2001 ER -