The Determination of Dendrite Coherency Point Characteristics Using Three New Methods for Aluminum Alloys

The aim of this work is to give an overview of existing methods and to introduce three new methods for the determination of the Dendrite Coherency Point (DCP) for AlSi10Mg alloys, as well as to compare the acquired values of DCP based on a thermal analysis and on the analysis of cooling curves working with only one thermocouple. Additionally, the impact of alloying and contaminant elements on the DCP will be also studied. The first two proposed methods employ the higher order derivatives of the cooling curves. The DCP was determined as the crossing point of the second and third derivative curves plotted versus time (method 1) or that of the temperature (method 2) with the zero line just after the maximum liquidus temperature. The third proposed method is based on the determination of the crossing point of the third solid fraction derivative curve with the zero line, corresponding to a minimum of the second derivative. A Taguchi design for the experiments was developed to study the DCP values in the AlSi10Mg alloy. The DCP temperature values of the test alloys were compared with the DCP temperatures predicted by the previous methods and the influence of the major and minor alloying elements and contaminants over the DCP. The new processes obtained a correlation factor r2 from 0.954 and 0.979 and a standard deviation from 1.84 to 2.6 °C. The obtained correlation values are higher or similar than those obtained using previous methods with an easier way to define the DCP, allowing for a better automation of the accuracy of DCP determination. The use of derivative curves plotted versus temperature employed in the last two proposed methods, where the test samples did not have an influence over the registration curves, is proposed to have a better accuracy than those of the previously described methods.This work has been partially funded by the Basque Government through the ETORGAI programme ZE-2016/00018 and from the European Union’s Seventh Programme for research, technological development and demonstration under grant agreement No. 296024

Schwerer Verlauf einer Miliartuberkulose bei einem 34-jährigen Patienten mit Colitis ulcerosa und HIV-Infektion unter einer TNF-α-Antikörper-Therapie

Zusammenfassung : Ein 34-jähriger HIV-positiver Patient mit Colitis ulcerosa unter Anti- Tumor-Nekrose-Faktor-(TNF-)α-Therapie mit Infliximab wurde bei zunehmender Verschlechterung des Allgemeinzustands mit intermittierend febrilen Temperaturen, progredienter Lymphopenie, Anämie, Thrombopenie und Neutropenie in die Klinik der Autoren überwiesen. Trotz negativer Screeninguntersuchungen vor Beginn und während der Therapie mit Infliximab wurde schließlich eine Miliartuberkulose diagnostiziert und eine tuberkulostatische Therapie begonnen. Im Verlauf kam es bei dem Patienten zu einer progredienten Verschlechterung des klinischen Zustandsbilds mit Entwicklung einer schweren exsudativ-nekrotisierenden Form der Pankreatitis. Im weiteren Verlauf verstarb der Patient unter zunehmender respiratorischer Erschöpfung nach Entwicklung von progredienten pulmonalen Infiltraten und Pleuraergüsse

Numerical and Experimental Investigation of Soil Behaviour Under Stationary Excitation

The effect of earthquakes on the behavior of soil and/or structures is usually investigated using earthquake-like signals as input for loading. This holds true for most of numerical and experimental simulations. In contrast to those approaches sinusoidal excitation was used here. The benefit of this type of excitation is an increased observability of the system, which is a precondition for a systematic investigation. Since sinusoidal excitation allows a gradually, step by step increase of the applied loading, the state of the soil (density and effective stress) as well as pore water pressure are transient. Therefore they are varying slowly and the modes of vibration are changing with time accordingly. The modes can be identified by regarding the contour of a soil column for instance. The evolution and distribution of pore water pressure (up to liquefaction) has to be captured simultaneously. A further advantage of this method is that asymptotic behavior can be investigated for the evolutions of pore water pressure and settlement of the surface with an increasing number of cycles. On the base of a numerical study some test in a shake-box will be shown using the described concept. Numerical modeling of soil behavior under cyclic respectively dynamic loading requires the application of nonlinear constitutive laws. With the used FE-model it is possible to observe the dependence of excitation amplitude, frequency and initial state on the transient amplification of the sinusoidal input signal up to an onset of liquefaction. The appropriate experimental investigations confirm the numerically observed behavior. Therefore a shake-box under 1-g conditions with smooth boundaries is used for the tests. They were performed with a homogeneous soil column (about 0.8m length, 0.6m width, 2.1m height) from medium-grained quartz sand under saturated conditions

Quantification of Feeding Regions of Hypoeutectic Al-(5, 7, 9)Si-(0-4)Cu (wt.%) Alloys Using Cooling Curve Analysis

This chapter presents the potential of the cooling curve analysis to characterize the solidification path of the cast hypoeutectic series of Al-Si-Cu alloys and to quantify their feeding regions. The aim of this work is to examine how variations in the chemical composition of Si (5, 7 and 9 wt.%) and Cu (from 0 to 4 wt.%) might affect the characteristic solidification temperatures, their corresponding fraction solid, and feeding regions of investigated alloys. These parameters collected from the cooling curve analysis can be used for better understanding of the solidification paths of Al-Si-Cu alloys and could easily be incorporated into existing simulation software packages to improve their accuracy

Evaluierung von Möglichkeiten zur biologischen Kontrolle der Reblaus durch den entomophagen Pilz Metarhizium anisopliae im ökologischen Weinbau

Seit einigen Jahren werden weltweit erneut Rückgangserscheinungen in Rebanlagen beobachtet, die auf Reblausbefall zurückgeführt werden. Reblausbefall an Wurzeln von Unterlagsreben kann zu vorzeitigem Blattfall, reduziertem Triebwachstum, Ertrags- und Qualitätsverlusten bis hin zum Absterben der Rebstöcke führen. Derzeit sind keine chemischen oder biologischen Pflanzenschutzmittel zur Reblauskontrolle verfügbar. Allerdings wurden in den letzten Jahren erhebliche Fortschritte bei der Entwicklung biologischer Schädlingskontrollorganismen erzielt. Innerhalb dieses Projektes wurden in einem Freilandversuch auf einer organisch bewirtschafteten Versuchsfläche die Effektivität, die Bodenpersistenz und die Einflüsse auf Non-target-Organismen von Metarhizium anisopliae untersucht. Hierbei wurden die mit Metarhizium behandelte Versuchsparzellen mit unbehandel-ten bzw. mit steriler Gerste behandelten Parzellen verglichen. Die Befallshäufigkeit (Porten & Huber 2003) der Rebstöcke mit Reblaus war dabei auf den mit Metarhizium behandelten Parzellen im Bereich der Fahrgasse signifikant geringer. Auch die Befallsintensität war signifikant reduziert. Zwei Monate nach der Applikation wurden für eine biologische Schädlingsbekämpfung ausreichende Dichten im Bereich der Fahrgasse festgestellt. Fünf Monate nach der Applikation wurden erhöhte Metarhizium-Dichten auch im Unterstockbereich auf den behandelten Parzellen gemessen. Bei den durchgeführten Non-target-Untersuchungen konnten im Versuchsvarianten-vergleich keine signifikanten Änderungen der Abundanz oder der Diversität bei Bodeninvertebraten (Ordungen Edaphon gesamt, Collembolen-, Carabiden- und Regenwurmarten) festgestellt werden. Auch bei den untersuchten konspezifischen Pilzzönosen wurden keine signifikanten Unterschiede zwischen den Versuchsvarianten festgestellt. Bei den oenologische Begeituntersuchungen (Ertrag, Beerengewicht, °BRIX, Most-pH) zeigten sich ebenfalls keine Unterschiede zwischen den untersuchten Versuchsvarianten

Traction force microscopy with optimized regularization and automated Bayesian parameter selection for comparing cells

Adherent cells exert traction forces on to their environment, which allows them to migrate, to maintain tissue integrity, and to form complex multicellular structures. This traction can be measured in a perturbation-free manner with traction force microscopy (TFM). In TFM, traction is usually calculated via the solution of a linear system, which is complicated by undersampled input data, acquisition noise, and large condition numbers for some methods. Therefore, standard TFM algorithms either employ data filtering or regularization. However, these approaches require a manual selection of filter- or regularization parameters and consequently exhibit a substantial degree of subjectiveness. This shortcoming is particularly serious when cells in different conditions are to be compared because optimal noise suppression needs to be adapted for every situation, which invariably results in systematic errors. Here, we systematically test the performance of new methods from computer vision and Bayesian inference for solving the inverse problem in TFM. We compare two classical schemes, L1- and L2-regularization, with three previously untested schemes, namely Elastic Net regularization, Proximal Gradient Lasso, and Proximal Gradient Elastic Net. Overall, we find that Elastic Net regularization, which combines L1 and L2 regularization, outperforms all other methods with regard to accuracy of traction reconstruction. Next, we develop two methods, Bayesian L2 regularization and Advanced Bayesian L2 regularization, for automatic, optimal L2 regularization. Using artificial data and experimental data, we show that these methods enable robust reconstruction of traction without requiring a difficult selection of regularization parameters specifically for each data set. Thus, Bayesian methods can mitigate the considerable uncertainty inherent in comparing cellular traction forces