The coccolithophorid unicellular alga Emiliania huxleyi is known to form large blooms, which have a strong effect on the marine carbon cycle. As a photosynthetic organism, it is subjected to a circadian rhythm due to the changing light conditions throughout the day. For a better understanding of the metabolic processes under these periodically-changing environmental conditions, a genome-scale model based on a genome reconstruction of the E. huxleyi strain CCMP 1516 was created. It comprises 410 reactions and 363 metabolites. Biomass composition is variable based on the differentiation into functional biomass components and storage metabolites. The model is analyzed with a flux balance analysis approach called diurnal flux balance analysis (diuFBA) that was designed for organisms with a circadian rhythm. It allows storage metabolites to accumulate or be consumed over the diurnal cycle, while keeping the structure of a classical FBA problem. A feature of this approach is that the production and consumption of storage metabolites is not defined externally via the biomass composition, but the result of optimal resource management adapted to the diurnally-changing environmental conditions. The model in combination with this approach is able to simulate the variable biomass composition during the diurnal cycle in proximity to literature data.
We present deformable mirrors for the intra-cavity use in high-power thin-disk laser resonators. The refractive power of these mirrors is continuously adaptable from -0.7 m-1 to 0.3 m-1, corresponding to radii of curvature ranging between 2.86 m (convex) and 6.67 m (concave). The optimized shape of the mirror membrane enables a very low peak-to-valley deviation from a paraboloid deformation over a large area. With the optical performance of our mirrors being equal to that of standard HR mirrors, we were able to demonstrate the tuning of the beam quality of a thin-disk laser in a range of M2 = 3 to M2 = 1 during laser operation at output powers as high as 1.1 kW.
Zusammenfassung
Optisch adressierte deformierbare Spiegel (OADMs, engl. für optically addressed deformable mirrors) können in Hochleistungslasern zur Kompensation thermisch induzierter Störungen und zur aktiven Strahlformung verwendet werden. In diesem Artikel wird ein Modellierungsansatz vorgestellt, der die vom OADM absorbierte Adressierstrahlung als verteilt-wirkenden Stelleingriff berücksichtigt. Zudem werden durch den Primärlaser verursachte Stördeformationen dargestellt. Mit geometrisch-physikalischen Argumenten wird das kontinuumsmechanische Modell vereinfacht: Da der Wärmefluss in Tiefenrichtung dominiert, kann diese Koordinate mittels partieller Ortsdiskretisierung als verteilte Größe beibehalten werden. Das resultierende verteilt-parametrische Entwurfsmodell stellt die Basis für late lumping-Steuerungs- und Regelungsmethoden dar und wird anhand experimenteller Daten validiert.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.