High-order methods for the numerical simulation of vortical and turbulent flows: Foreword

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webchem: An R Package to Retrieve Chemical Information from the Web

A wide range of chemical information is freely available online, including identifiers, experimental and predicted chemical properties. However, these data are scattered over various data sources and not easily accessible to researchers. Manual searching and downloading of such data is time-consuming and error-prone. We developed the open-source R package webchem that allows users to automatically query chemical data from currently 14 web sources. These cover a broad spectrum of information. The data are automatically imported into an R object and can directly be used in subsequent analyses. webchem enables easy, structured and reproducible data retrieval and usage from publicly available web sources. In addition, it facilitates data cleaning, identification and reporting of substances. Consequently, it reduces the time researchers need to spend on chemical data compilation

Secondary frequency control stabilising voltage dynamics

The ongoing energy transition challenges the stability of the electrical power system. Stable operation of the electrical power grid requires both the voltage (amplitude) and the frequency to stay within operational bounds. While much research has focused on frequency dynamics and stability, the voltage dynamics has been neglected. Here, we study frequency and voltage stability in the case of simple networks via linear stability and bulk analysis. In particular, our linear stability analysis of the network shows that the frequency secondary control guarantees the stability of a particular electric network. Even more interesting, while we only consider secondary frequency control, we observe a stabilizing effect on the voltage dynamics, especially in our numerical bulk analysis.Comment: 10 pages, 7 figure

Assessing the intergranular crack initiation probability of a grain boundary distribution by an experimental misalignment study of adjacent slip systems

Crack initiation at grain boundaries due to blocked slip transfer of dislocations is a main failure mechanism during the fatigue of metals. A quantification of the resistance effect of a grain boundary is needed to assess a textured or texture-free microstructure for fatigue strength. Geometric approaches based on the misalignment of slip systems in adjacent grains are widely used. Hence, we validated the geometric transmission factor of Shen et al. in coarse-grained high-purity aluminum under the assumption that the combination of a large slip activity and a blocked slip at a grain boundary leads to intergranular crack initiation and revealed that a detailed knowledge of the 3D-orientation of the grain boundary is essential. Thereby we gathered information about the 3D-microstructure using FIB-cross-sectioning. Hence it is possible to evaluate potential crack initiation sites for a specific microstructure or to estimate the fatigue strength of a textured microstructure in terms of a crack initiation probability

Plasma-Treated Water Affects Listeria Monocytogenes Vitality and Biofilm Structure

Plasma-generated compounds (PGCs) such as plasma-processed air (PPA) or plasma-treated water (PTW) offer an increasingly important alternative for the treatment of microorganisms in hard-to-reach areas found in several industrial applications including the food industry. To this end, we studied the antimicrobial capacity of plasma-treated water on the vitality and biolm formation of Listeria monocytogenes, a common food spoilage microorganism. Using a microwave plasma (MidiPLexc), 10 ml of deionized water was treated for 100 s, 300 s and 900 s (pretreatment time) and the bacterial biolm was subsequently exposed to the PTW for 1 min, 3 min and 5 min (posttreatment time) for each pretreatment time separately. Colony-forming units (CFU), metabolic activity, and cell vitality were reduced for 4.7 log10 , 47.9%, and 69.5%, respectively. Live/dead staining and uorescence microscopy showed a positive correlation between treatment and incubation times and reduction in vitality. Atomic force microscopy indicated a change in the plasticity of the bacteria. These results suggest a promising antimicrobial impact of plasma-treated water on Listeria monocytogenes, which may lead to more targeted applications of plasma decontamination in the food industry in the future

Simulations of dense granular gases without gravity with impact-velocity-dependent restitution coefficient

We report two-dimensional simulations of strongly vibrated granular materials without gravity. The coefficient of restitution depends on the impact velocity between particles by taking into account both the viscoelastic and plastic deformations of particles, occurring at low and high velocities respectively. Use of this model of restitution coefficient leads to new unexpected behaviors. When the number of particles N is large, a loose cluster appears near the fixed wall, opposite the vibrating wall. The pressure exerted on the walls becomes independent of N, and linear in the vibration velocity V, quite as the granular temperature. The collision frequency at the vibrating wall becomes independent of both N and V, whereas at the fixed wall, it is linear in both N and V. These behaviors arise because the velocity-dependent restitution coefficient introduces a new time scale related to the collision velocity near the cross over from viscoelastic to plastic deformation.Comment: Final version - To be published in Powder Technolog