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Analysis of multiphase tranport phenomena in PEMFCs by incorporating microscopic model for catalyst layer structure

The catalyst layer (CL) in polymer electrolyte membrane (PEM) fuel cells is one of the key components regulating the overall performance of the cell. In PEM fuel cells, there are two CLs having identical composition for hydrogen oxidation (HO) and oxygen reduction (OR) reactions. There are four phases inside the CL, namely: carbon, Pt particles, ionomer and voids. In this work, a micro-model of th

Splitting the Least-Mean-Square Algorithm

The least-mean-square (LMS) algorithm is an adaptation scheme widely used in practice due to its simplicity. In some applications the involved signals are continuous-time. Then, usually either a fully analog implementation of the LMS algorithm is applied or the input data are sampled by analog-to-digital (AD) converters to be processed digitally. A purely digital realization is most often the pref

Greening the world economy through cities

Besides comprising a majority of the world’s population, cities concentrate disproportional amounts of the world’s economy and decision-making power. Further, though urban areas cover only around two percent of the Earth’s surface, they consume 75 percent of its resources. Yet as a hub for social and political movements and centres of technological and institutional knowledge and innovation, citie

Extreme Hardness Achievements in Binderless Cubic Boron Nitride Tools

Binderless cubic boron nitride tools are available in two forms: single phase cBN and dual phase wBN/cBN (w is wurtzite phase). In this work, a novel heat treatment process involving surface heating using a continuous wave CO2 laser followed by tandem waterjet quenching of the laser beam path was applied to increase the hardness of both forms of boron nitride. Stress-induced phase transitions and

Optimal intra-symbol transmit windowing for multicarrier modulation

Windowing of the transmitted blocks in a multicarrier system yields an improved spectral containment of the resulting basis functions, which allows larger transmit power compared to no windowing while fulfilling the power spectral density (PSD) requirements. Most transmit window designs proposed so far aim at maximising the mainlobe energy and thus the spectral containment of the transmit basis fu