Layered Lanthanide Coinage-Metal Diarsenides: Syntheses, Commensurately and Incommensurately Modulated Structures, Electric and Magnetic Properties: Layered Lanthanide Coinage-Metal Diarsenides: Syntheses, Commensurately and Incommensurately Modulated Structures, Electric and Magnetic Properties

The crystal structures of the LnAgAs2 and LnAuAs2 compounds were reinvestigated by single-crystal diffraction experiments. Contrary to the respective copper compounds, no stuffed variant of the HfCuSi2 type was found. For CeAuAs2, GdAuAs2 and TbAuAs2, a slight under-occupation of the gold position was determined, the other compounds crystallize in a 1:1:2 ratio. Additionally, LaCuAs2 was synthesized for the first time in a 1:1:2 ratio. Due to the fact that imaging plate diffraction systems were used instead of four-circle diffractometers, satellite reflections could be observed for most of the LnCuAs2 compounds (Ln = Ce, Nd, Sm, Gd, Tb, Ho), CeAuAs2, GdAuAs2 and TbAuAs2. Structure models of GdCuAs2, CeAuAs2, GdAuAs2 and TbAuAs2 were developed, rod and layer groups of the respective structural motives were determined and approximants were presented.Die Kristallstrukturen der LnAgAs2 und LnAuAs2 Verbindungen wurden mittels Einkristallbeugungsexperimenten neu untersucht. Im Gegensatz zu den jeweiligen Kupferverbindungen wurde keine gefüllte Variante des HfCuSi2-Typs gefunden. Im Falle von CeAuAs2, GdAuAs2 und TbAuAs2 wurde eine geringfügige Unterbesetzung der Gold-Position bestimmt, die anderen Verbindungen kristallisieren in einem 1:1:2-Verhältnis. Weiterhin wurde erstmals LaCuAs2 in diesem Verhältnis synthetisiert. Aufgrund der Verwendung von Bildplattensystemen an Stelle von Vierkreisdiffraktometern konnten Satellitenreflexe für den Großteil der LnCuAs2-Verbindungen (Ln = Ce, Nd, Sm, Gd, Tb, Ho), CeAuAs2, GdAuAs2 and TbAuAs2 beobachtet werden. Strukturmodelle von GdCuAs2, CeAuAs2, GdAuAs2 und TbAuAs2 wurden entwickelt, Stab- und Ebenengruppen der einzelnen Strukturmotive wurden bestimmt und Approximanten präsentiert

A Textured Silicon Calorimetric Light Detector

We apply the standard photovoltaic technique of texturing to reduce the reflectivity of silicon cryogenic calorimetric light detectors. In the case of photons with random incidence angles, absorption is compatible with the increase in surface area. For the geometrically thin detectors studied, energy resolution from athermal phonons, dominated by position dependence, is proportional to the surface-to-volume ratio. With the CaWO4 scintillating crystal used as light source, the time constants of the calorimeter should be adapted to the relatively slow light-emission times.Comment: Submitted to Journal of Applied Physic

Automatic Roof Plane Detection and Analysis in Airborne Lidar Point Clouds for Solar Potential Assessment

A relative height threshold is defined to separate potential roof points from the point cloud, followed by a segmentation of these points into homogeneous areas fulfilling the defined constraints of roof planes. The normal vector of each laser point is an excellent feature to decompose the point cloud into segments describing planar patches. An object-based error assessment is performed to determine the accuracy of the presented classification. It results in 94.4% completeness and 88.4% correctness. Once all roof planes are detected in the 3D point cloud, solar potential analysis is performed for each point. Shadowing effects of nearby objects are taken into account by calculating the horizon of each point within the point cloud. Effects of cloud cover are also considered by using data from a nearby meteorological station. As a result the annual sum of the direct and diffuse radiation for each roof plane is derived. The presented method uses the full 3D information for both feature extraction and solar potential analysis, which offers a number of new applications in fields where natural processes are influenced by the incoming solar radiation (e.g., evapotranspiration, distribution of permafrost). The presented method detected fully automatically a subset of 809 out of 1,071 roof planes where the arithmetic mean of the annual incoming solar radiation is more than 700 kWh/m2

UNMANNED AERIAL VEHICLE LASER SCANNING FOR EROSION MONITORING IN ALPINE GRASSLAND

With this contribution we assess the potential of unmanned aerial vehicle (UAV) based laser scanning for monitoring shallow erosion in Alpine grassland. A 3D point cloud has been acquired by unmanned aerial vehicle laser scanning (ULS) at a test site in the subalpine/alpine elevation zone of the Dolomites (South Tyrol, Italy). To assess its accuracy, this point cloud is compared with (i) differential global navigation satellite system (GNSS) reference measurements and (ii) a terrestrial laser scanning (TLS) point cloud. The ULS point cloud and an airborne laser scanning (ALS) point cloud are rasterized into digital surface models (DSMs) and, as a proof-of-concept for erosion quantification, we calculate the elevation difference between the ULS DSM from 2018 and the ALS DSM from 2010. For contiguous spatial objects of elevation change, the volumetric difference is calculated and a land cover class (bare earth, grassland, trees), derived from the ULS reflectance and RGB colour, is assigned to each change object. In this test, the accuracy and density of the ALS point cloud is mainly limiting the detection of geomorphological changes. Nevertheless, the plausibility of the results is confirmed by geomorphological interpretation and documentation in the field. A total eroded volume of 672 m3 is estimated for the test site (48 ha). Such volumetric estimates of erosion over multiple years are a key information for improving sustainable soil management. Based on this proof-of-concept and the accuracy analysis, we conclude that repeated ULS campaigns are a well-suited tool for erosion monitoring in Alpine grassland