Johannes Kepler University of Linz

About: Johannes Kepler University of Linz is a education organization based out in Linz, Oberösterreich, Austria. It is known for research contribution in the topics: Computer science & Thin film. The organization has 6605 authors who have published 19243 publications receiving 385667 citations.

Thermodynamics and structure of hydrogen, methane, argon, oxygen, and carbon dioxide adsorbed on single-wall carbon nanotube bundles

Abstract: Adsorption isotherms, isosteric heats of adsorption, and neutron diffraction measurements of hydrogen, methane, argon, oxygen, and carbon dioxide adsorbed on single-wall carbon nanotube bundles show that all species, except $\mathrm{C}{\mathrm{O}}_{2}$, condense first on high-energy binding sites, such as the grooves and the widest interstitial channels, and then on the outer rounded surface of the bundles. As for $\mathrm{C}{\mathrm{O}}_{2}$, only one set of adsorption sites is observed, which is attributed mainly to the grooves. The diffraction results further reveal that the average packing of the bundles is not changed upon adsorption and that no significant overall bundle dilation is observed on our sample. Molecular dynamic simulations confirm and complete our interpretation.

Money laundering: some facts

Abstract: This paper tackles the quite difficult topic of money laundering. After defining money laundering, and after explaining the three stages (steps), placement, layering and integration, the paper tries a quantification and estimation of the volume and development of money laundering activities. Besides it shows national and international measurements to fight money laundering and various effects on macroeconomics. The overall turnover in organized crime for example had a value of 800 billion USD in 2001 and increased to 1.700 billion USD in 2007. These figures are very preliminary with a quite large error, but give a clear indication how important money laundering and the turnover of organized crime is nowadays.

A semantic web middleware for virtual data integration on the web

Abstract: In this contribution a system is presented, which provides access to distributed data sources using Semantic Web technology. While it was primarily designed for data sharing and scientific collaboration, it is regarded as a base technology useful for many other Semantic Web applications. The proposed system allows to retrieve data using SPARQL queries, data sources can register and abandon freely, and all RDF Schema or OWL vocabularies can be used to describe their data, as long as they are accessible on the Web. Data heterogeneity is addressed by RDF-wrappers like D2R-Server placed on top of local information systems. A query does not directly refer to actual endpoints, instead it contains graph patterns adhering to a virtual data set. A mediator finally pulls and joins RDF data from different endpoints providing a transparent on-the-fly view to the end-user. The SPARQL protocol has been defined to enable systematic data access to remote endpoints. However, remote SPARQL queries require the explicit notion of endpoint URIs. The presented system allows users to execute queries without the need to specify target endpoints. Additionally, it is possible to execute join and union operations across different remote endpoints. The optimization of such distributed operations is a key factor concerning the performance of the overall system. Therefore, proven concepts from database research can be applied.

Global warming potential of hydrogen and methane production from renewable electricity via power-to-gas technology

Abstract: Power-to-gas technology enables storage of surplus electricity from fluctuating renewable sources such as wind power or photovoltaics, by generating hydrogen (H2) via water electrolysis, with optional methane (CH4) synthesis from carbon dioxide (CO2) and H2; the advantage of the latter is that CH4 can be fed into existing gas infrastructure. This paper presents a life cycle assessment (LCA) of this technological concept, evaluating the main parameters influencing global warming potential (GWP) and primary energy demand. The conducted LCA of power-to-gas systems includes the production of H2 or CH4 from cradle to gate. Product utilization was not evaluated but considered qualitatively during interpretation. Material and energy balances were modeled using the LCA software GaBi 5 (PE International). The assessed impacts of H2 and CH4 from power-to-gas were compared to those of reference processes, such as steam reforming of natural gas and crude oil as well as natural gas extraction. Sensitivity analysis was used to evaluate the influence of the type of electricity source, the efficiency of the electrolyzer, and the type of CO2 source used for methanation. The ecological performance of both H2 and CH4 produced via power-to-gas strongly depends on the electricity generation source. The assessed impacts of H2 production are only improved if GWP of the utilized electricity does not exceed 190 g CO2 per kWh. Due to reduced efficiency, the assessed impacts of CH4 are higher than that of H2. Thus, the environmental break-even point for CH4 production is 113 g CO2 per kWh if utilized CO2 is treated as a waste product, and 73 g CO2 per kWh if the CO2 separation effort is included. Electricity mix of EU-27 countries is therefore not at all suitable as an input. Utilization of renewable H2 and CH4 in the industry or the transport sector offers substantial reduction potential in GWP and primary energy demand. H2 and CH4 production through power-to-gas with electricity from renewable sources, such as wind power or photovoltaics, offers substantial potential to reduce GWP and primary energy demand. However, the input of electricity predominately generated from fossil resources leads to a higher environmental impact of H2 and CH4 compared to fossil reference processes and is not recommended. As previously bound CO2 is re-emitted when CH4 is utilized for instance in vehicles, the type of CO2 source and the allocation method have a significant influence on overall ecological performance.