Linear mixed-integer models for biomass supply chains with transport,storage and processing

This paper presents a linear mixed-integer modeling approach for basic components in a biomass supply chain including supply, processing, storage and demand of different types of biomass. The main focus in the biomass models lies on the representation of the relationship between moisture and energy content in a discretized framework and on handling of long-term processes like storage with passive drying effects in the optimization. The biomass models are formulated consistently with current models for gas, electricity and heat infrastructures in the optimization model ‘eTransport’, which is designed for planning of energy systems with multiple energy carriers. To keep track of the varying moisture content in the models and its impact on other biomass properties, the current node structure in eTransport has been expanded with a special set of biomass nodes. The Node, Supply, Dryer and Storage models are presented in detail as examples of the approach. A sample case study is included to illustrate the functionality implemented in the models.     

PIXE measurements of Renaissance silverpoint drawings at VERA

Silverpoint drawings from the Renaissance are among the most precious and rarest treasures of graphical art. Our research group is particularly interested in the analysis of silverpoint drawings by Albrecht Dürer (1471-1528). A very sensitive and non-destructive analytical method, either spatially resolved synchrotron-radiation induced X-ray fluorescence (SY-XRF) or proton-induced X-ray emission (PIXE), is needed to determine the chemical composition of the very faint silver marks on such drawings. Dürer drawings from the collection of the Albertina, Vienna, were analyzed to amend existing data on Dürer drawings. For this purpose an external-beam PIXE setup was installed at the Vienna Environmental Research Accelerator (VERA). It allows to analyze a spot of ∼0.15 mm on the object in air with 3 MeV protons, and to detect the emitted X-rays that are characteristic for the chemical composition with very good sensitivity and without harming the precious objects. After successful measurements on artificial test samples, four original silverpoint drawings were investigated: two portraits from Albrecht Dürer’s very early period (self-portrait and portrait of his father) and two drawings from Dürer’s sketch book of his travel to the Netherlands 1520/21.     

Solutions of plates on a heterogeneous elastic foundation

In this paper the solution of the problem of interaction of a plate with a two parameter elastic foundation is presented. Vertical displacements of rectangular plates having free edges resting on a heterogeneous elastic foundation have been analysed by using of finite element method. The heterogeneity of the foundation caused by the orthotropy has been taken into account when forming the equations of equilibrium and variable thickness of the foundation by approximating it by Haar's functions. The obtained results have been compared with the results for a homogeneous foundation.