Semantics in the wild : a digital assistant for Flemish citizens

Public service fragmentation across more than 800 digital channels of government administrations in the region of Flanders (Belgium), causes administrative burden and frustrations, as citizens expect a coherent service. Given the autonomy of the various entities, the fragmentation of information and budget constraints, it is not feasible to rewire the entire e-gov ecosystem to a single portal. Therefore, the Flemish Government is building a smart digital assistant, which supports citizens on the governmental portals, by integrating status information of various transactions. This paper outlines our ongoing research on a method for raising semantic interoperability between different information systems and actors. In this approach, semantic agreements are maintained and implemented end-to-end using the design principles of Linked Data. The lessons learned can speed-up the process in other countries that face the complexity of integrating e-government portals

Improved Performance of Polymer Electrolyte Membrane Fuel Cells with Modified Microporous Layer Structures

A possible method to improve membrane humidity conditions in polymer electrolyte membrane fuel cells and, therefore, the cell performance is the optimization of microporous layer MPL structures. In this work, water transport in modified MPL materials in polymer electrolyte membrane fuel cells PEMFCs was investigated by in amp; 8197;operando synchrotron X ray tomography. Three different types of MPLs are compared A reference standard MPL material, an MPL material with a special wavy structure, and an MPL with randomly distributed holes. We found a strong impact of the modified MPL structure on the water distribution at operating temperatures of 40 and 55 amp; 8201; C and an increase of cell performance up to 14 amp; 8201; compared to the reference cell. We assume the water distribution at the membrane to be responsible for the performance increase and provide a detailed discussion

Nano scale Monte Carlo study on liquid water distribution within the polymer electrolyte membrane fuel cell microporous layer, catalyst layer and their interfacial region

Liquid water saturation of pores in the gas diffusion layer GDL and the catalyst layer CL of polymer electrolyte membrane fuel cells PEMFC hinders the transport of the reactant gases, leading to inhomogeneous current density distribution, reduced overall cell performance, and accelerated material degradation. This effect restricts the PEMFC operation, specifically at high current densities. In this study, the simulation results illustrate how the interplay of wettability and pore sizes influences the water distribution within the CL, microporous layer MPL of the GDL, and specifically their interface. The liquid water distribution within the porous material is studied employing a voxel based Monte Carlo MC model reflecting the effect of local thermodynamic boundary conditions and inner surface characteristics. Real material structures obtained with a focused ion beam scanning electron microscope FIB SEM are employed. Local temperature and relative humidity values required as inputs are obtained from sophisticated computational fluid dynamics CFD simulations comprising all relevant effects, including the electrochemical reactions. The results show that avoiding drastic changes in wettability at the CL MPL interface can help to mitigate the possible detrimental water accumulations. Further developing and exploiting this study will contribute to facilitate the systematic material development for better PEMFC performance and durabilit

Investigations on dynamic water transport characteristics in flow field channels using neutron imaging techniques

Handling of water accumulation is still a key issue in fuel cell research. The presented study evaluates the condensate removal capability of three different flow field designs. The designs are compared regarding cell voltage at different current densities using the same operating conditions. The investigated type of meander shaped channels with a high degree of parallelization shows the best performance with stationary water thickness inside channels throughout the analyzed current densities. To develop and evaluate a condensate removal criterion for fuel cell construction, the pressure drop of each flow field is correlated to the water appearance visualized with neutron radiography. For a further insight, computational fluid dynamics simulation is used to calculate pressure drops present inside the characteristic regions of each flow field. Thus, a characteristic design limit of 20 mbar m 1 for meander shaped channels is proven to ensure the absence of channel blockage. The meander shaped channels show specific pressure drops around this limit depending on water production and gas supply. The two other analyzed flow fields suffer from higher channel filling rates the investigated straight channels with less parallelization fill up with time, while the pattern structured flow field demonstrates gravity as an additional influence on condensate remova

X ray Tomographic Investigation of Water Distribution in Polymer Electrolyte Membrane Fuel Cells with Different Gas Diffusion Media

In this study, water transport in polymer electrolyte membrane fuel cells PEMFCs is investigated by synchrotron X ray tomography. The measurement technique is used to reveal the relationship between the structure of the gas diffusion media GDM and the water distribution. It is shown how the water distribution and transport is visualized and quantitatively analyzed. We present investigations on three different GDM A GDM with a modified microporous layer MPL , a thick GDM with limited back diffusion and a reference materia