Novel Analytical Calculation Method for the Non-Linear Ψ -i- Characteristic of Switched-Reluctance-Machines in Arbitrary Rotor Positions

Abstract The non-linear Ψ -i-characteristic is crucial for the design of switched reluctance machines. Known analytical calculations are based on complex models of the magnetic circuit or on functions needing a fitting procedure (using measured or FEM-calculated data). In this paper, a method is presented that requires only very few input data, which can be deduced easily from the geometry of the machine. Comparisons with measured data show an acceptable correlation for arbitrary rotor positions, qualifying this method to be used in the design stage of new drives

Mastering of NIL Stamps with Undercut T-Shaped Features from Single Layer to Multilayer Stamps

Biomimetic structures such as structural colors demand a fabrication technology of complex three-dimensional nanostructures on large areas. Nanoimprint lithography (NIL) is capable of large area replication of three-dimensional structures, but the master stamp fabrication is often a bottleneck. We have demonstrated different approaches allowing for the generation of sophisticated undercut T-shaped masters for NIL replication. With a layer-stack of phase transition material (PTM) on poly-Si, we have demonstrated the successful fabrication of a single layer undercut T-shaped structure. With a multilayer-stack of silicon oxide on silicon, we have shown the successful fabrication of a multilayer undercut T-shaped structures. For patterning optical lithography, electron beam lithography and nanoimprint lithography have been compared and have yielded structures from 10 µm down to 300 nm. The multilayer undercut T-shaped structures closely resemble the geometry of the surface of a Morpho butterfly, and may be used in future to replicate structural colors on artificial surfaces

The Use of Bio-Waste for Biomethane Production in European Cities

The simultaneous energetic use of bio-waste, such as municipal solid waste (MSW) and catering/food waste, and the creation of a closed nutrient cycle is one of the main advantages of anaerobic digestion (AD) biogas plants as they convert waste materials to "desirable" feedstock. When compared to other treatment opportunities of the organic fraction of MSW, AD has several advantages. In comparison to waste incineration plants, AD plants usually need lower investments and the distances for feedstock transport are generally shorter. Nutrients can be easier recovered for agricultural production and wet feedstock does not have to be dried which is required for incineration. Similar to household scale or industrial scale composting, AD processes also recover nutrients, but the energy content of the biomass is not utilised. In many European regions waste management is still a large problem and only few biogas plants use bio-waste for biogas production. Insufficient waste management practices are more dominant in urban areas. At the same time, European countries have to comply with the Landfill Directive 1999/31/EC and with the Waste Framework Directive (WFD) 2008/98/EC to considerably reduce land filling of the biodegradable part of MSW. They also have to comply with the Renewable Energy Directive (RED) 2009/28/EC. AD from waste has the potential to contribute to the European targets of the above mentioned directives. Adjacent upgrading to biomethane quality and grid injection in the natural gas distribution network is an opportunity to efficiently use renewable energy in urban areas. This approach, Waste-to-Biomethane (WtB), is promoted by the UrbanBiogas project (Urban waste for biomethane grid injection and transport in urban areas; May 2011 – April 2014) which is supported by the Intelligent Energy for Europe Programme of the European Union. The use of the untapped fraction of organic urban waste for biogas production is promoted by a bottom-up approach in which cities (municipalities) are directly involved in all UrbanBiogas activities. The objective is to prepare 5 European target cities for the production of biomethane from urban waste which will be fed into the natural gas grids and optionally used for transport. The target cities are: City of Zagreb (Croatia), Municipality of Abrantes (Portugal), City of Graz (Austria), City of Rzeszów (Poland), and North Vidzeme Region including the City of Valmiera (Latvia). Core of the project is the implementation of working group meetings in the target cities, study tours and city exchange visits, in order to elaborate five WtB concepts for the target cities. The present paper gives an overview on options for the use of bio¬waste for biogas production. It shows current European legislation which supports the use of separate collected bio¬waste in AD facilities. Finally, it presents the UrbanBiogastarget cities and the UrbanBiogas activities in order to promote the WtB concept