A Mass-Preserving Two-Step Lagrange–Galerkin Scheme for Convection-Diffusion Problems

Journal of Scientific Computing - In this paper, we propose and analyze a mixed finite element scheme for stationary inductionless magnetohydrodynamic equations on a general Lipschitz domain. We...     

Transport processes at single droplets in micellar liquid/liquid systems

In many industrial applications, the knowledge of the occurring transport processes in liquid/liquid systems is of great interest to design a multiphase reactor or an extraction column, for instance. All transport processes in liquid/liquid systems are governed by the interface. In some processes surfactants are needed. Surfactants change many interfacial properties which affect the transport processes. In this work, the influence of high surfactant concentrations (micellar systems) on transport processes is regarded. To understand, the occurring reduction of the drop rise velocity and of mass transfer rates experimental investigations of the occurring interfacial phenomena are carried out. Therefore, interfacial tension measurements as well as colloidal probe atomic force measurements of liquid/liquid systems were conducted. It was proved that for high nonionic surfactant concentrations a change of the phase behavior must be taken into consideration to describe transport processes in micellar liquid/liquid systems. © 2014 American Institute of Chemical Engineers AIChE J, 61: 1092–1104, 2015     

Trend-specific clustering for micro mass production of linked parts

In micro production, small tolerances, as well as size effects increase the requirement for a fast, precise, and reliable methodology that enhances the output of assemblies. In contrast to conventional approaches, a widening of the tolerance field enables an overall improvement of the output of a process chain while assuring functionality of parts. Therefore, the consideration of trends for building sections is essential for increasing the outcome by identifying sections that can be matched. This paper presents the Linked Parts Clustering Algorithm for the identification of trend-specific clusters in linked parts and demonstrates the area of application.     

What determines entry? Evidence from Sweden

In this paper, I examined what conditions affected the entry of Swedish limited liability firms 2000–2008, while making a distinction between regular entrants and those that survive for at least 2 years. I used a dataset that makes it possible to trace entry geographically as well as in what industry it occurs down to the 5-digit NACE level. Results suggest that the conditions influencing regular entry were similar to those influencing surviving entry. Political variables, e.g., municipal tax rate and the ideology of local rule, were of limited importance. Meanwhile, municipalities with industries with high minimum efficient scale of production or high market concentration rates were considerably less likely to see new firm formation. Substantially, more entry occurred in municipalities with high-income and a well-educated population. The importance of the level of education appears stronger for surviving entrants than for regular entrants, pointing to the importance of human capital.     

Crystallization kinetics of V2AlC

X-ray amorphous V₂AlC and hexagonal (V,Al)₂C_x thin films were synthesized by magnetron sputtering from a compound target with the composition of V₂AlC. The crystallization kinetics was investigated by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). During continuous heating up to 1200 °C, one exothermal peak is observed between 565 and 675 °C. XRD data suggest that the DSC peak is associated with the formation of V₂AlC. The activation energy of crystallization of V₂AlC is ~ 308 kJ/mol based on the Kissinger approach. This value is close to the 287 kJ/mol activation energy obtained here for the transformation of magnetron sputtered (V,Al)₂C_x thin films to V₂AlC. The here reported phase formation temperature of V₂AlC is about 800 °C lower than during hot pressing of elemental powders.     

Ultrahigh Mass Activity Pt Entities Consisting of Pt Single atoms,Clusters, and Nanoparticles for Improved Hydrogen Evolution Reaction

Platinum is one of the best-performing catalysts for the hydrogen evolution reaction (HER). However, high cost and scarcity severely hinder the large-scale application of Pt electrocatalysts. Constructing highly dispersed ultrasmall Platinum entities is thereby a very effective strategy to increase Pt utilization and mass activities, and reduce costs. Herein, highly dispersed Pt entities composed of a mixture of Pt single atoms, clusters, and nanoparticles are synthesized on mesoporous N-doped carbon nanospheres. The presence of Pt single atoms, clusters, and nanoparticles is demonstrated by combining among others aberration-corrected annular dark-field scanning transmission electron microscopy, X-ray absorption spectroscopy, and electrochemical CO stripping. The best catalyst exhibits excellent geometric and Pt HER mass activity, respectively ≈4 and 26 times higher than that of a commercial Pt/C reference and a Pt catalyst supported on nonporous N-doped carbon nanofibers with similar Pt loadings. Noteworthily, after optimization of the geometrical Pt electrode loading, the best catalyst exhibits ultrahigh Pt and catalyst mass activities (56 ± 3 A mg⁻¹_Pt and 11.7 ± 0.6 A mg⁻¹_Cat at −50 mV vs. reversible hydrogen electrode), which are respectively ≈1.5 and 58 times higher than the highest Pt and catalyst mass activities for Pt single-atom and cluster-based catalysts reported so far.     

A high throughput optical system for imaging optodes

The objective of this study was to design a high throughput macro imaging system for intensity ratio based optodes, which facilitate both extensive replication and large number of samples to fulfill the statistical requirements for understanding natural processes occurring over extended time. The suggested system accommodates up to 24 sample cells with a field of view of 35 mm or 12 sample cells and 12 calibration cells for a seamless replacement of the optodes to follow processes that last longer than the optode lifetime. The individual components such as sample turrets, LED light sources, filters and lens designs are tested and discussed in detail. Positioning and alignment of an adjacent cell is completed within 6 s with an accuracy of five pixels. The acceleration profile for the sample turret is software controlled, which makes it possible to study e.g. sediments with overlaying water without effects from re-suspension. Calibration is performed by simultaneous filling of all the flow-cells with calibration solution and thereafter a sample run is executed. Thus, the effort required for calibration is the same regardless of the number of sample cells used. The system is automated and controlled through Matlab (Mathworks Inc), which is also is used for post processing of the images. The system was designed for an environmental application where more than 2000 individual images were collected and calibrated to yield 360 sample images.     

Towards Standardized and Automated Fault Management and Service Provisioning for NGNs

The IP Multimedia Subsystem (IMS), already widely recognized as a fundamental core component of Next Generation Networks (NGNs), enables proliferation of a huge variety of value added services. Simultaneous to the emergence of triple play services there is a strong need for establishing standardized methodologies for service fulfillment and assurance, maintaining service execution parameters at advertised levels. Traditional Operations Support Systems (OSS) are not adequate for managing NGNs. This work shows experiences gained from implementing OSS for NGNs. It describes a solution that combines extensive NGN development expertise with a new generation, of policy-based, service oriented OSS solutions in order to provide enhanced levels of automation and reliability to the NGN service delivery and session control environment. Primary focus of this approach is put on service assurance and service fulfillment mechanisms for remote monitoring, automated control and configuration of standard compliant IMS infrastructures, such as the Open Source IMS Core (OSIMS) based Open IMS Playground. This work describes state of the art NGN OSS design principles and knowledge attained by integration of standardized fault management as well as service and subscriber provisioning procedures showing how the full cycle from service deployment to service advertisement to service execution can be delivered in an automated way.