Mesoscopic simulation of diffusive contaminant spreading in gas flows at low pressure

Many modern production and measurement facilities incorporate multiphase systems at low pressures. In this region of flows at small, non-zero Knudsen- and low Mach numbers the classical mesoscopic Monte Carlo methods become increasingly numerically costly. To increase the numerical efficiency of simulations hybrid models are promising. In this contribution, we propose a novel efficient simulation approach for the simulation of two phase flows with a large concentration imbalance in a low pressure environment in the low intermediate Knudsen regime. Our hybrid model comprises a lattice-Boltzmann method corrected for the lower intermediate Kn regime proposed by Zhang et al. for the simulation of an ambient flow field. A coupled event-driven Monte-Carlo-style Boltzmann solver is employed to describe particles of a second species of low concentration. In order to evaluate the model, standard diffusivity and diffusion advection systems are considered.Comment: 9 pages, 8 figure

Новые клинические и диагностические стратегии при раке почки

Представлен анализ изменившейся клиники опухолей почки. Описаны динамика и последовательность использования новых визуализирующих методов диагностики.The analysis of the changed clinical picture of renal tumors is done. The dynamics and sequence of the new imaging techniques are described

Prediction of Electrolyte Distribution in Technical Gas Diffusion Electrodes From Imaging to SPH Simulations

The performance of the gas diffusion electrode GDE is crucial for technical processes like chlorine alkali electrolysis. The function of the GDE is to provide an intimate contact between gaseous reactants, the solid catalyst, and the liquid electrolyte. To accomplish this, the GDE is composed of wetting and non wetting materials to avoid electrolyte breakthrough. Knowledge of the spatial distribution of the electrolyte in the porous structure is a prerequisite for further improvement of GDE. Therefore, the ability of the electrolyte to imbibe into the porous electrode is studied by direct numeric simulations in a reconstructed porous electrode. The information on the geometry, including the information on silver and PTFE distribution of the technical GDE, is extracted from FIB SEM imaging including a segmentation into the different phases. Modeling of wetting phenomena inside the GDE is challenging, since surface tension and wetting of the electrolyte on silver and PTFE surfaces must be included in a physically consistent manner. Recently, wetting was modeled from first principles on the continuum scale by introducing a contact line force. Here, the newly developed contact line force model is employed to simulate two phase flow in the solid microstructures using the smoothed particle hydrodynamics SPH method. In this contribution, we present the complete workflow from imaging of the GDE to dynamic SPH simulations of the electrolyte intrusion process. The simulations are used to investigate the influence of addition of non wetting PTFE as well as the application of external pressure differences between the electrolyte and the gas phase on the intrusion proces

Investigating the electrowetting of silver based gas diffusion electrodes during oxygen reduction reaction with electrochemical and optical methods

Porous gas diffusion electrodes GDEs are widely used in electrochemical applications where a gaseous reactant is converted to a target product. Important applications for silver based GDEs are the chlor alkali and the CO2 electrolysis processes in which silver catalyzes the oxygen or carbon dioxide reduction reaction. The wetting of the porous GDEs is of utmost importance for the achieved performance of the electrode a completely dry electrode will result in low current densities due to the reduced active surface area while on the other hand, a completely flooded electrode will deteriorate the access of the gaseous reactant. Therefore, we investigated silver based GDEs for the oxygen reduction reaction with different amounts of the hydrophobic agent polytetrafluoroethylene PTFE and analyzed the potential induced wetting behavior electrowetting . The electrolyte breakthrough was recorded by a digital microscope and subsequently evaluated via imaging analysis of the observed breached electrolyte droplets. In order to characterize the wetting state during transition to the steady state, we applied electrochemical impedance spectroscopy measurements and retrieved the double layer capacitance. Our results indicate that a higher overvoltage facilitates the breakthrough of electrolytes through the gas diffusion electrode. Surprisingly, a faster breakthrough of electrolyte was observed for electrodes with higher PTFE content. Porometry measurements revealed that the GDE with low PTFE content has a monomodal pore size distribution, whereas electrodes with higher PTFE amount exhibit a bimodal pore size distribution. In GDEs with monomodal pore size distribution the time in which the double layer capacitance is leveling off correlates with the breakthrough time of the electrolyte. In summary, we emphasize that the wetting of GDEs is a complex interplay of the applied potential, electrode composition, and resulting porous structure which requires further advanced measurements and analysis considering the parameters affecting the wetting behavior as a whol

Competition and moral behavior: A meta-analysis of forty-five crowd-sourced experimental designs

Significance Using experiments involves leeway in choosing one out of many possible experimental designs. This choice constitutes a source of uncertainty in estimating the underlying effect size which is not incorporated into common research practices. This study presents the results of a crowd-sourced project in which 45 independent teams implemented research designs to address the same research question: Does competition affect moral behavior? We find a small adverse effect of competition on moral behavior in a meta-analysis involving 18,123 experimental participants. Importantly, however, the variation in effect size estimates across the 45 designs is substantially larger than the variation expected due to sampling errors. This “design heterogeneity” highlights that the generalizability and informativeness of individual experimental designs are limited. Abstract Does competition affect moral behavior? This fundamental question has been debated among leading scholars for centuries, and more recently, it has been tested in experimental studies yielding a body of rather inconclusive empirical evidence. A potential source of ambivalent empirical results on the same hypothesis is design heterogeneity—variation in true effect sizes across various reasonable experimental research protocols. To provide further evidence on whether competition affects moral behavior and to examine whether the generalizability of a single experimental study is jeopardized by design heterogeneity, we invited independent research teams to contribute experimental designs to a crowd-sourced project. In a large-scale online data collection, 18,123 experimental participants were randomly allocated to 45 randomly selected experimental designs out of 95 submitted designs. We find a small adverse effect of competition on moral behavior in a meta-analysis of the pooled data. The crowd-sourced design of our study allows for a clean identification and estimation of the variation in effect sizes above and beyond what could be expected due to sampling variance. We find substantial design heterogeneity—estimated to be about 1.6 times as large as the average standard error of effect size estimates of the 45 research designs—indicating that the informativeness and generalizability of results based on a single experimental design are limited. Drawing strong conclusions about the underlying hypotheses in the presence of substantive design heterogeneity requires moving toward much larger data collections on various experimental designs testing the same hypothesis