Suchergebnisse

"After having investigated the geodesic and translation triangles and their angle sums in Nil and SL_2R geometries we consider the analogous problem in Sol space that is one of the eight 3-dimensional Thurston geometries. We analyse the interior angle sums of translation triangles in Sol geometry and prove that it can be larger or equal than pi . In our work we will use the projective model of Sol described by E. Molnar in [9]."

The Geometric System of the Nave Vault of the Church on the Hill of Sighişoara. The literature on the methods of late Gothic net vault constructions mainly accentuates ideas, which presume that the initial conditions of the design are orderly. However, in the case of buildings of multiple building periods, this is rarely the case. In the present article, we present the point cloud-based geometric analysis of the net vault system of the Church on the Hill of Sighişoara. Our results highlight that contrary to the generally accepted theories, the construction of a net vault is not necessarily initiated with the plan of the rib system, and that the underlying principle organising the whole system's geometry is not always the plan pattern. Our case study also exemplifies how the Gothic principles of unity and division still blend with the ideas of separation and addition, even in a late Gothic hall church with direct connections to the guild of Landshut.
Keywords: masonry ribbed net vault; late Gothic vault construction; geometric analysis; Church on the Hill of Sighişoara; Gothic construction principles

The thermal behavior of Cu-doped TiO2 gels obtained by the sol-gel method was investigated by thermogravimetric and differential thermal analysis (TG/DTG/DTA) and differential scanning calorimetry (DSC) measurements. The comparative investigation of the structure and morphology of the as-prepared gels and of the nanopowders obtained by annealing them was realized by transmission electron microscopy (TEM), Fourier transmission infrared spectroscopy (FTIR), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Significant differences were noticed depending on the amount of dopant (0.5 or 2.0 mol % CuO). A higher dopant concentration resulted in a more complex decomposition of the sample. This behavior was associated with the formation of various molecular species in the sol-gel solutions before gelation, determined by the different amount of the dopant used.