INVESTIGATION OF BIOGAS DIGESTATE AS FIBER MATERIALS FOR COMPOSITES

Fiber reinforced plastics with synthetic fibers are widely used. Plant fibers are also known to produce more sustainable composites. However, there is a great interest in finding alternatives to classical natural fibers. The digestate of biogas plants seems to be such an alternative. Biogas plants are fed with plant-based substrates and during the digestion, the biomass is degraded. In this study, the fiber quality of digestates from four biogas plants with different initial substrates is investigated. Therefore, typical fiber properties, such as slenderness ratio, cell wall components, and the potential fiber performance, are measured. According to the general definition, the solid part of the digestate is a fiber material. The slenderness ratio is 5 or higher and the density is 1.5 gcm23, which is typical for natural fibers. Fibers with similar properties are already used in composite materials

Weighted automata define a hierarchy of terminating string rewriting systems

The "matrix method" (Hofbauer and Waldmann 2006) proves termination of string rewriting via linear monotone interpretation into the domain of vectors over suitable semirings. Equivalently, such an interpretation is given by a weighted finite automaton. This is a general method that has as parameters the choice of the semiring and the dimension of the matrices (equivalently, the number of states of the automaton). We consider the semirings of nonnegative integers, rationals, algebraic numbers, and reals; with the standard operations and ordering. Monotone interpretations also allow to prove relative termination, which can be used for termination proofs that consist of several steps. The number of steps gives another hierarchy parameter. We formally define the hierarchy and we prove that it is infinite in both directions (dimension and steps)

Stochastic Delay Prediction in Large Train Networks

In daily operation, railway traffic always deviates from the planned schedule to a certain extent. Primary initial delays of trains may cause a whole cascade of secondary delays of other trains over the entire network. In this paper, we propose a stochastic model for delay propagation and forecasts of arrival and departure events which is applicable to all kind of public transport (not only to railway traffic). Our model is fairly realistic, it includes general waiting policies (how long do trains wait for delayed feeder trains), it uses driving time profiles (discrete distributions) on travel arcs which depend on the departure time, and it incorporates the catch-up potential of buffer times on driving sections and train stops. The model is suited for an online scenario where a massive stream of update messages on the current status of trains arrives which has to be propagated through the whole network. Efficient stochastic propagation of delays has important applications in online timetable information, in delay management and train disposition, and in stability analysis of timetables. The proposed approach has been implemented and evaluated on the German timetable of 2011 with waiting policies of Deutsche Bahn AG. A complete stochastic delay propagation for the whole German train network and a whole day can be performed in less than 14 seconds on a PC. We tested our propagation algorithm with artificial discrete travel time distributions which can be parametrized by the size of their fluctuations. Our forecasts are compared with real data. It turns out that stochastic propagation of delays is efficient enough to be applicable in practice, but the forecast quality requires further adjustments of our artificial travel time distributions to estimates from real data

Effect Of A Dark Matter Halo On The Determination Of Black Hole Masses

Stellar dynamical modeling is a powerful method to determine the mass of black holes in quiescent galaxies. However, in previous work the presence of a dark matter halo has been ignored in the modeling. Gebhardt & Thomas in 2009 showed that accounting for a dark matter halo increased the black hole mass of the massive galaxy M87 by a factor of two. We used a sample of 12 galaxies to investigate the effect of accounting for a dark matter halo in the dynamical modeling in more detail, and also updated the masses using improved modeling. The sample of galaxies possesses Hubble Space Telescope and ground-based observations of stellar kinematics. Their black hole masses have been presented before, but without including a dark matter halo in the models. Without a dark halo, we find a mean increase in the estimated mass of 1.5 for the whole sample compared to previous results. We attribute this change to using a more complete orbit library. When we include a dark matter halo, along with the updated models, we find an additional increase in black hole mass by a factor of 1.2 in the mean, much less than for M87. We attribute the smaller discrepancy in black hole mass to using data that better resolve the black hole's sphere of influence. We redetermined the M-center dot-sigma(*) and M-center dot-L-V relationships using our updated black hole masses and found a slight increase in both normalization and intrinsic scatter.DAADDeutsche Forschungsgemeinschaft SPP1177, Wi 1369/23-2NSF 0908639Astronom

Förderansätze im Lesen mit LEVUMI

Das Lehrerhandbuch „Förderansätze im LESEN mit LEVUMI“ verknüpft die Anwendung der Lernverlaufsdiagnostik mit konkreten Fördermaßnahmen. Im Mittelpunkt steht immer der Lernerfolg der Leseanfängerinnen und Leseanfängern. Es ist wichtig, dass Förderungen und Unterstützungen im Unterricht an die individuellen Förderungen angepasst sind. Daher wird der Schriftspracherwerb, der Kieler Leseaufbau und typische Probleme im Leseerwerb dargestellt. Einzelne Förderbausteine werden erklärt und anhand einzelner Arbeitsblätter dargestellt. Dieses Handbuch ergänzt das „LEVUMI Lehrerhandbuch“ (Gebhardt, Diehl & Mühling, 2016), welches eine konkrete Einführung und Anwendungsbeschreibung in die Lernverlaufsmessung mit LEVUMI enthält

A correlation between central supermassive black holes and the globular cluster systems of early-type galaxies

Elliptical, lenticular, and early-type spiral galaxies show a remarkably tight power-law correlation between the mass M_BH of their central supermassive black hole (SMBH) and the number N_GC of globular clusters: M_BH=m*N_GC^(1.08+/-0.04) with m=1.7*10^5 solar masses. Thus, to a good approximation the SMBH mass is the same as the total mass of the globular clusters. Based on a limited sample of 13 galaxies, this relation appears to be a better predictor of SMBH mass (rms scatter 0.2 dex) than the M_BH-sigma relation between SMBH mass and velocity dispersion sigma. The small scatter reflects the fact that galaxies with high globular cluster specific frequency S_N tend to harbor SMBHs that are more massive than expected from the M_BH-sigma relation.Comment: 14 pages, 3 figures, to appear in ApJ 720, 516 (2010

Spectral theory for the failure of linear control in a nonlinear stochastic system

We consider the failure of localized control in a nonlinear spatially extended system caused by extremely small amounts of noise. It is shown that this failure occurs as a result of a nonlinear instability. Nonlinear instabilities can occur in systems described by linearly stable but strongly nonnormal evolution operators. In spatially extended systems the nonnormality manifests itself in two different but complementary ways: transient amplification and spectral focusing of disturbances. We show that temporal and spatial aspects of the nonnormality and the type of nonlinearity are all crucially important to understanding and describing the mechanism of nonlinear instability. Presented results are expected to apply equally to other physical systems where strong nonnormality is due to the presence of mean flow rather than the action of control.Comment: Submitted to Physical Review

Der Schulbegleiter muss vom Typ her offen sein. Eine Interviewstudie zur Kooperation zwischen Lehrkräften und Schulbegleitern im Gymnasium

Schulbegleitung ist in vielen Schulen eine Unterstützungsmaßnahme für die inklusive Schule. Um die Kooperation zwischen Schulbegleitern und Lehrkräften in inklusiven Klassen zu betrachten, wurden drei Lehrkräfte und zwei Schulbegleiter in Gymnasien in Oberbayern interviewt. Die Auswertung zeigt, dass reguläre Lehrkräfte, nach eigenen Angaben, wenig Wissen über Sonderpädagogik und Inklusion haben und die Zusammenarbeit nur unter bestimmten Umständen gelingt

The contact of graphene with Ni(111) surface: description by modern dispersive forces approaches

Here we present a Density Functional Theory (DFT) study on the suitability of modern corrections for the inclusion of dispersion related terms (DFT-D) in treating the interaction of graphene and metal surfaces, exemplified by the graphene/Ni(111) system. The Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional is used as basis, on top of which we tested the family of Grimme corrections (D2 and D3, including Becke-Jonson damping and Andersson approach) as well as different flavors of the approach by Tkatchenko and Scheffler (TS). Two experimentally observed chemisorbed states, top-fcc and bridge-top conformations, were examined, as well as one physisorbed situation, the hcp-fcc state. Geometric, energetic, and electronic properties were compared to sets of experimental data for our model system of graphene/Ni(111), but also for available data of bulk Ni, graphite, and free-standing graphene. Results show that two of the most recent approximations, the fully ab initio TS-MBD, and the semi-empirical Grimme D3 correction are best suited to describe graphene↔metal contacts, yet, comparing to earlier studies, the Rev-vdW-DF2 functional is also a good option, whereas optB86-vdW and optB88b-vdW functionals are fairly close to experimental values to be harmless used. The present results highlight how different approaches for the approximate treatment of dispersive forces yield different results, and so fine-tuning and testing of the envisioned approach for every specific system is advisable. The present survey clears the path for future accurate and affordable theoretical studies of nanotechnologic devices based on graphene-metal contacts