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This paper describes the modeling of a fuel cell system, a model-based development of corresponding automation strategies, and an experimental evaluation of the model and automation on a scaled system test rig. The developed system model includes the fuel cell stack and associated peripheral components such as air blowers and valves. The focus of the modeling is laid on transient effects and, in particular, the influences of stack temperature, partial pressures and humidities of the reaction gases on the voltage characteristics of the stacks. The automation strategy developed in the subsequent step includes control of hydrogen pressure, air ratio and coolant temperature using PI controllers. The automation strategy also includes a superordinate state machine for controlling and monitoring the entire system. The automation strategy is evaluated experimentally on two stacks which are electrically interconnected in parallel. The challenge of an unequal current distribution between fuel cell stacks due to different stack performances is also addressed. In order to be able to react to larger load changes and to failure cases, the switching on and off of an entire stack during operation is also investigated and evaluated for the parallel interconnection.

The complexity of propeller wing interactions in a distributed propulsion (DP) configuration requires high quality wind tunnel data to fully exploit the benefit of such a configuration. Benefits of DP are most pronounced in high lift, high thrust configurations, which sets the focus for the proposed experiment. The designed wind tunnel model features a two element wing with three co-rotating propulsion units on a separate carrier that can be readily traversed and pitched relative to the wing. This enables a thorough investigation of propeller position from 0 x/D 1 and -0.25 z/D 0.25, excluding nacelle effects. Experiments are conducted up to Re = 2.9 * 10^6 based on wing chord. The 2D wing spans 2.4 m in the closed test section of the Propulsion Test Facility, TU Braunschweig. It features an adjustable fowler flap. To avoid data contamination from side wall effects, the model is split in three sections, each representing a periodic section from an infinite DP wing. While the outboard sections provide the quasi periodic conditions but suffer from side wall effects, the centre section is instrumented. This includes angle resolved thrust and torque measurements of the drive train, internal 6K force measurement on the profile section and pressure sensitive paint on the suction side. Multiple sets of propellers with two different diameters are installed, following different design strategies. A homogeneous induced axial velocity design and a MIL propeller are compared regarding propeller wing interaction. The constant speed propellers are pitched to deliver thrust in the range of 0.07 cT 0.3 at two different advance ratios. The propellers are designed to have a constant Matip for all operation points and a scaled D/c, J and cT . With the proposed instrumentation plan a full set of integral parameters for drive train and wing can be measured, while keeping the configuration highly modular. Time resolved pressure measurement and time-averaged PSP allow an in depth analysis of three dimensional pressure distribution and instationary effects on the wing.

Das Luftmanagementsystem eines Brennstoffzellenflugzeugs versorgt die Brennstoffzelle mit verdichteter, befeuchteter und erwärmter Umgebungsluft. Die Wahl der optimalen Betriebsparameter und der besten Systemarchitektur ist insbesondere in großen Flughöhen eine komplexe Optimierungsaufgabe. Diese Arbeit untersucht auf Grundlage eines analytischen Modells den Entwurfsraum eines solchen Luftmanagementsystems. Als wichtigste Freiheitsgrade konnten die Wahl des Verdichtungsverhältnisses, der Sauerstoffstöchiometrie und der Befeuchtung stromauf der Brennstoffzelle identifiziert werden. Die wesentlichen Limitierungen des Entwurfsraums sind die Wasserbilanzen von Brennstoffzelle und System, sowie die maximal mögliche Befeuchtung. Für zwei Anwendungsfälle wurden optimale Betriebsparameter und Systemarchitekturen bestimmt. Es wurde gezeigt, dass Turbinen von grundlegender Bedeutung für den Wasserhaushalt und die Effizienz des Systems sind. Außerdem ist in den meisten Fällen eine Verdampfungskühlung der verdichteten Luft ausreichend. Ein Wärmetauscher wird nicht benötigt.

Hintergrund/Fragestellung: Pflegende in anderen europäischen Ländern übernehmen deutlich erweiterte Aufgaben in der pharmazeutischen Versorgung, zum Beispiel die Verschreibung vorab festgelegter Medikamente. Im Rahmen der europäischen Studie DeMoPhaC in 14 Ländern[zum vollständigen Text gelangen Sie über die oben angegebene URL], Who cares? – EbM und Transformation im Gesundheitswesen; 22. Jahrestagung des Deutschen Netzwerks Evidenzbasierte Medizin

Pharmacophagy involves the sequestration of specialised plant metabolites for non-nutritive purposes and commonly occurs in insects. Here we investigate pharmacophagy in the turnip sawfly, Athalia rosae, where adults not only collect specialised metabolites (clerodanoids) from a plant (Ajuga reptans), but also from the exterior of conspecifics via fighting. Using behavioural assays, chemical analytics, and RNAseq we show that when individuals nibble on conspecifics that have already acquired clerodanoids from A. reptans leaves, this nibbling results in the transfer of compounds between individuals. Furthermore, unlike other pharmacophagous insects, the acquisition of clerodanoids by A. rosae from the leaves of A. reptans does not induce the upregulation of known detoxification or sequestration genes and pathways. In contrast, pharmacophagous nibbling on conspecifics results in the upregulation of metabolic pathways associated with elevated metabolic rates and increased energy consumption. It therefore seems that individuals attack conspecifics to acquire clerodanoids despite the apparent metabolic costs of this form of pharmacophagy compared to clerodanoid uptake from a plant. Changes in the metabolic phenotype of A.rosae individuals consequently has profound consequences for social interactions with possible ramifications for their social niche.Summary statementThe turnip sawfly (Athalia rosae) gains potentially beneficial compounds from the leaf surface of non-food plants (e.g. Ajuga reptans), but can also steal these compounds from conspecifics via aggressive nibbling.

Soft/flexible PEG-based polymer nanotubes released doxorubicin over a sustained period and reduced tumor growth in a metastatic breast cancer model., Nanotubes are emerging as promising materials for healthcare applications but the selection of clinically relevant starting materials for their synthesis remains largely unexplored. Here we present, for the first time, the synthesis of poly(ethylene glycol) (PEG) based nanotubes via the photopolymerization of poly(ethylene glycol) diacrylate and other diacrylate derivatives within the pores of anodized aluminum oxide templates. Template-assisted synthesis allowed the manufacture of a diverse set of polymeric nanotubes with tunable physical characteristics including diameter (∼200–400 nm) and stiffness (405–902 kPa). PEG nanotubes were subjected to cytotoxicty assessment in cell lines and primary stem cells and showed excellent cytocompatability (IC50 > 120 μg ml–1). Nanotubes were readily drug loaded but released the majority of the drug over 5 days. Direct administration of drug loaded nanotubes to human orthotopic breast tumors substantially reduced tumor growth and metastasis and outperformed i.v. administration at the equivalent dose. Overall, this nanotube templating platform is emerging as a facile route for the manufacture of poly(ethylene glycol) nanotubes.

China enjoys considerable popularity in the Middle East and Africa, not only among elites but also at street level. This article draws on international relations theories to explain this general pattern, as well as intra- and interregional variation. Every approach has something to contribute, but international political economy more so than realism. Constructivist theories are particularly useful in explaining China’s popularity in the Middle East and Africa.

This article makes the case for process patterns as an alternative to causal mechanisms. Causal mechanisms are explanatory tools to unpack the “black boxes” separating the input and output of models. Unlike causal mechanisms, process patterns do not require such a black box. They refer to recurrent sequences of interaction observed across any number of empirical domains. Scholars can apply them across disciplines when similar processes occur in different domains. The article provides examples from International Relations where scholars have sometimes studied process patterns in all but name.