Techno-economic heat transfer optimization of large scale latent heat energy storage systems in solar thermal power plants

Concentrated solar power plants with integrated storage systems are key technologies for sustainable energy supply systems and reduced anthropogenic CO2-emissions. Developing technologies include direct steam generation in parabolic trough systems, which offer benefits due to higher steam temperatures and, thus, higher electrical efficiencies. However, no large scale energy storage technology is available yet. A promising option is a combined system consisting of a state-of-the art sensible molten salt storage system and a high temperature latent heat thermal energy storage system (LHTESS). This paper discusses the systematic development and optimization of heat transfer structures in LHTESS from a technological and economic point of view. Two evaluation parameters are developed in order to minimize the specific investment costs. First, the specific product costs determine the optimum equipment of the latent heat storage module, i.e. the finned tube. The second parameter reflects the interacting behavior of the LHTESS and the steam turbine during discharge. This behavior is described with a simplified power block model that couples both components

Deep learning image analysis for filamentous fungi taxonomic classification: Dealing with small datasets with class imbalance and hierarchical grouping

Deep learning applications in taxonomic classification for animals and plants from images have become popular, while those for microorganisms are still lagging behind. Our study investigated the potential of deep learning for the taxonomic classification of hundreds of filamentous fungi from colony images, which is typically a task that requires specialized knowledge. We isolated soil fungi, annotated their taxonomy using standard molecular barcode techniques, and took images of the fungal colonies grown in petri dishes (n = 606). We applied a convolutional neural network with multiple training approaches and model architectures to deal with some common issues in ecological datasets: small amounts of data, class imbalance, and hierarchically structured grouping. Model performance was overall low, mainly due to the relatively small dataset, class imbalance, and the high morphological plasticity exhibited by fungal colonies. However, our approach indicates that morphological features like color, patchiness, and colony extension rate could be used for the recognition of fungal colonies at higher taxonomic ranks (i.e. phylum, class, and order). Model explanation implies that image recognition characters appear at different positions within the colony (e.g. outer or inner hyphae) depending on the taxonomic resolution. Our study suggests the potential of deep learning applications for a better understanding of the taxonomy and ecology of filamentous fungi amenable to axenic culturing. Meanwhile, our study also highlights some technical challenges in deep learning image analysis in ecology, highlighting that the domain of applicability of these methods needs to be carefully considered

Hole Solutions in the 1d Complex Ginzburg-Landau Equation

The cubic Complex Ginzburg-Landau Equation (CGLE) has a one parameter family of traveling localized source solutions. These so called 'Nozaki-Bekki holes' are (dynamically) stable in some parameter range, but always structually unstable: A perturbation of the equation in general leads to a (positive or negative) monotonic acceleration or an oscillation of the holes. This confirms that the cubic CGLE has an inner symmetry. As a consequence small perturbations change some of the qualitative dynamics of the cubic CGLE and enhance or suppress spatio-temporal intermittency in some parameter range. An analytic stability analysis of holes in the cubic CGLE and a semianalytical treatment of the acceleration instability in the perturbed equation is performed by using matching and perturbation methods. Furthermore we treat the asymptotic hole-shock interaction. The results, which can be obtained fully analytically in the nonlinear Schroedinger limit, are also used for the quantitative description of modulated solutions made up of periodic arrangements of traveling holes and shocks.Comment: 20 pages (RevTex) , 7 figures (postscript

Classically entangled optical beams for high-speed kinematic sensing

Tracking the kinematics of fast-moving objects is an important diagnostic tool for science and engineering. Existing optical methods include high-speed CCD/CMOS imaging, streak cameras, lidar, serial time-encoded imaging and sequentially timed all-optical mapping. Here, we demonstrate an entirely new approach to positional and directional sensing based on the concept of classical entanglement in vector beams of light. The measurement principle relies on the intrinsic correlations existing in such beams between transverse spatial modes and polarization. The latter can be determined from intensity measurements with only a few fast photodiodes, greatly outperforming the bandwidth of current CCD/CMOS devices. In this way, our setup enables two-dimensional real-time sensing with temporal resolution in the GHz range. We expect the concept to open up new directions in photonics-based metrology and sensing.Comment: v2 includes the real-time measurement from the published version. Reference [29] added. Minor experimental details added on page

Enhancing scientific literacy by means of practical inquiry - development and evaluation of an inquiry-oriented course for the first senior year of high school

Durch internationale Vergleichsstudien wie PISA und TIMSS hat sich der Stellenwert naturwissenschaftlicher Grundbildung (Scientific Literacy) im allgemeinbildenden Curriculum national und international manifestiert. Im SDDS-Modell von Klahr (2000) wird Scientific Inquiry, eine wesentliche Dimension von Scientific Literacy, analog zu einem kognitionspsychologischen Problemlöseprozess modelliert. Die vorgestellte Studie berichtet über die Entwicklung und Evaluation eines kompetenzorientierten und fächerübergreifend angelegten Naturwissenschaftskurses, der sich dem Problem der mangelnden naturwissenschaftlichen Grundbildung stellt, indem über eine sukzessive Aneignung der einzelnen Schritte des SDDS-Modells die Schüler und Schülerinnen an das (natur)wissenschaftliche Denken herangeführt werden sollen. Als einsemestriger, erfahrungsbasiert konzipierter Experimentierkurs sollte der Kurs v.a. zu einem aufgeklärten Verständnis des hypothetisch-deduktiven Erkenntnisgangs beitragen. Das Ziel, eine deutliche Verbesserung von Scientific Inquiry der Schülerinnen und Schüler (SuS), wurde erreicht, wobei in einem besonderen Maß schwächere Schüler und Schülerinnen von dem Kurs profitierten. (DIPF/Orig.)In the aftermath of international comparative studies like PISA and TIMSS the German school administration started to orient science-curricula towards the major concept of scientific literacy which is internationally regarded as a basic competence. The SDDSmodel by Klahr (2000) describes scientific inquiry, a dimension of scientific literacy, as a process similar to problem-solving. This study presents the development and evaluation of a competence-oriented and interdisciplinary science course aiming to improve students\u27 scientific literacy. By means of bringing the students closer to the standards of scientific reasoning they were introduced to the steps of the SDDS model successively. Therefore, the one-semester course mainly was directed to foster scientific inquiry through experiences in experimental work. Its objective, to improve the students\u27capabilities in scientific inquiry, was fulfilled. The course was particularly beneficial for low achievers. (DIPF/Orig.

First Report on Alternative Evaluation Methodology PROMISE Deliverable 4.1

The first report on alternative evaluation methodology summarizes work done within the PROMISE environment and especially within Work package 4 - Evaluation Metrics and Methodologies. The report outlines efforts to develop and support alternative, automated evaluation methodologies, with a special focus on generating ground truth from existing data sources like Log files or annotations. Events like LogCLEF 2011, PatOlympics 2011 or the CHiC2011 workshop are presented and reviewed on their impact on the three main uses case domains

The impact of sulfur hexafluoride (SF₆) sinks on age of air climatologies and trends

Mean age of air (AoA) is a common diagnostic for the strength of the stratospheric overturning circulation in both climate models and observations. AoA climatologies and AoA trends over the recent decades of model simulations and proxies derived from observations of long-lived tracers do not agree. Satellite observations show much older air than climate models, and while most models compute a clear decrease in AoA over the last decades, a 30-year time series from measurements shows a statistically nonsignificant positive trend in the Northern Hemisphere extratropical middle stratosphere. Measurement-based AoA derivations are often founded on observations of the trace gas sulfur hexafluoride (SF$_{6}$), a fairly long-lived gas with a near-linear increase in emissions during recent decades. However, SF$_{6}$ has chemical sinks in the mesosphere that are not considered in most model studies. In this study, we explicitly compute the chemical SF$_{6}$ sinks based on chemical processes in the global chemistry climate model EMAC (ECHAM/MESSy Atmospheric Chemistry). We show that good agreement between stratospheric AoA in EMAC and MIPAS (Michelson Interferometer for Passive Atmospheric Sounding) is reached through the inclusion of chemical SF$_{6}$ sinks, as these sinks lead to a strong increase in the stratospheric AoA and, therefore, to a better agreement with MIPAS satellite observations. Remaining larger differences at high latitudes are addressed, and possible reasons for these differences are discussed. Subsequently, we demonstrate that the AoA trends are also strongly influenced by the chemical SF6 sinks. Under consideration of the SF$_{6}$ sinks, the AoA trends over the recent decades reverse sign from negative to positive. We conduct sensitivity simulations which reveal that this sign reversal does not result from trends in the stratospheric circulation strength nor from changes in the strength of the SF$_{6}$ sinks. We illustrate that even a constant SF$_{6}$ destruction rate causes a positive trend in the derived AoA, as the amount of depleted SF$_{6}$ scales with increasing SF$_{6}$ abundance itself. In our simulations, this effect overcompensates for the impact of the accelerating stratospheric circulation which naturally decreases AoA. Although various sources of uncertainties cannot be quantified in detail in this study, our results suggest that the inclusion of SF$_{6}$ depletion in models has the potential to reconcile the AoA trends of models and observations. We conclude the study with a first approach towards a correction to account for SF$_{6}$ loss and deduce that a linear correction might be applicable to values of AoA of up to 4 years

Experimentierend zu mehr Selbstbestimmung: Der Basiskurs Naturwissenschaften : Theoretische Leitlinien und empirische Hinweise

Mit dem Begriff Scientific Literacy wird die Forderung verbunden, Schule solle Schüler*innen naturwissenschaftliches Wissen und jene Kompetenzen vermitteln, durch die sie in die Lage versetzt werden, naturwissenschaftliches Wissen anwenden zu können. In Auseinandersetzung mit Konzepten zur Scientific Literacy und empirischen Erkenntnissen aus Fachdidaktiken und Bildungsforschung wurde von einer interdisziplinär zusammengesetzten Gruppe aus Lehrenden, Erziehungswissenschaftler*innen und Fachdidaktiker*innen ein naturwissenschaftliches Curriculum für die Eingangsphase der gymnasialen Oberstufe entwickelt und erprobt. Das Kurskonzept legt dabei den Schwerpunkt auf Scientific Inquiry mit dem Experiment als einer methodischen Grundform der Erkenntnisgewinnung. Der Erkenntnisprozess beim Experimentieren wird in einzelne Schritte unterteilt. Durch eine schrittweise Steigerung der Selbststeuerung beim Experimentieren soll es ermöglicht werden, dass der metakognitive Anforderungsgehalt von den Schüler*innen bewältigt werden kann und ihnen sowohl das Erleben von Autonomie als auch von Kompetenz ermöglicht wird. Ein weiterer Fokus im Kurskonzept liegt auf Data Literacy, die durch eine stetige Auseinandersetzung und Reflexion der Schüler*innen mit den von ihnen erhobenen Daten im gesamten Forschungsprozess gefördert werden soll. Analog zu den Schritten beim Experimentieren werden die dafür notwendigen mathematischen und statistischen Kompetenzen zunächst lehrerzentriert eingeführt und dann immer weiter in die Hände der Schüler*innen gelegt. Empirische Hinweise deuten darauf hin, dass durch die Kurskonzeption für Schüler*innen lernförderliche Lernumgebungen geschaffen werden können. Im Rahmen dieses Beitrags sollen die Grundlagen des Curriculumskonzeptes des Basiskurses Naturwissenschaften vorgestellt werden und so interessierten Lehrenden die Möglichkeit gegeben werden, Anregungen für ihren eigenen Unterricht zu finden