The intrinsic quality assessment of building footprints data on OpenStreetMap in Baden-Württemberg

In this work, we propose a framework to assess the quality of OpenStreetMap (OSM) building footprints data without using any reference data. More specifically, the OSM history data will be examined regarding the development of attributes, geometries and positions of building footprints. In total seven quality indicators are defined for the intrinsic quality assessment. For our case study in the federal state of Baden-Württemberg (BW), Germany, a PostgreSQL database is established based on a spatiotemporal data model which can track both individual objects and editing events on OSM. The preliminary experiments show that the quality of building footprints in BW is relatively high. And the quality in terms of semantics, geometries and positions are getting increasingly high over the time thanks to the considerable contribution of OSM volunteers.In dieser Arbeit stellen wir ein Konzept zur Bewertung von der Qualität von Gebäudegrundrissen aus OpenStreetMap (OSM) ohne Verwendung von Referenzdaten vor. Insbesondere wird der Verlauf der Bearbeitung von Stützpunkten und Attributen der Objekte untersucht. Sieben Indikatoren Bewertung der intrinsischen Datenqualität wurden definiert. Für die vorliegende Studie ist am Beispiel von Baden-Württemberg eine PostgreSQL-Datenbank erstellt worden, um ein räumlich-zeitliches Datenmodell zu implementieren, welches sowohl einzelne Objekte als auch Bearbeitungsereignisse (Events) verfolgen kann. Vorläufige Ergebnisse zeigen eine relativ hohe Qualität der OSM-Gebäudedaten, wobei eine Steigerung der Qualität hinsichtlich Semantik, Geometrie und Positionsgenauigkeit als Beitrag der freiwilligen OSM-Bearbeiter zu beobachten ist

Three dimensional photonic Dirac points in metamaterials

Topological semimetals, representing a new topological phase that lacks a full bandgap in bulk states and exhibiting nontrivial topological orders, recently have been extended to photonic systems, predominantly in photonic crystals and to a lesser extent, metamaterials. Photonic crystal realizations of Dirac degeneracies are protected by various space symmetries, where Bloch modes span the spin and orbital subspaces. Here, we theoretically show that Dirac points can also be realized in effective media through the intrinsic degrees of freedom in electromagnetism under electromagnetic duality. A pair of spin polarized Fermi arc like surface states is observed at the interface between air and the Dirac metamaterials. These surface states show linear k-space dispersion relation, resulting in nearly diffraction-less propagation. Furthermore, eigen reflection fields show the decomposition from a Dirac point to two Weyl points. We also find the topological correlation between a Dirac point and vortex/vector beams in classic photonics. The theoretical proposal of photonic Dirac point lays foundation for unveiling the connection between intrinsic physics and global topology in electromagnetism.Comment: 15 pages, 5 figure

CO 2

Recently, various composites for reducing CO2 emissions have been extensively studied. Because of their high sorption capacity and low cost, alkali metal carbonates are recognized as a potential candidate to capture CO2 from flue gas under moist conditions. However, undesirable effects and characteristics such as high regeneration temperatures or the formation of byproducts lead to high energy costs associated with the desorption process and impede the application of these materials. In this study, we focused on the regeneration temperature of carbon aerogel–potassium carbonate (CA–KC) nanocomposites, where KC nanocrystals were formed in the mesopores of the CAs. We observed that the nanopore size of the original CA plays an important role in decreasing the regeneration temperature and in enhancing the CO2 capture capacity. In particular, 7CA–KC, which was prepared from a CA with 7 nm pores, exhibited excellent performance, reducing the desorption temperature to 380 K and exhibiting a high CO2 capture capacity of 13.0 mmol/g-K2CO3, which is higher than the theoretical value for K2CO3 under moist conditions

Using coal rejects and tailings as infills for standing supports in underground gateroads

Laboratory tests were conducted to investigate the uniaxial compressive strength (UCS) of two types of potential infill materials for standing supports. While one type of infill material was made from coal reject fines and a cementitious grout, the other was a mixture of tailings and a cementitious grout. 81 cylindrical specimens with a 50 mm diameter and 100 mm height were prepared and tested. The effect of various water-to-grout (w/g) ratios and grout-to-coal reject fines/tailings mix ratios on the UCS of the infills were investigated. Test results indicated that the strength of both infills was adversely affected by the w/g ratio. In addition, when the volume ratio of the coal reject fines in the infill was not greater than 50%, the strength of the infill was similar to that of the control group specimens. Interestingly, almost all the infills made of tailings and grout had a greater UCS when compared with the control group. The infill made from 50% tailings and 50% grout with the w/g ratio of 1.2 achieved the highest strength enhancement ratio, being 1.92 times the UCS of the control group

Removal of Methyl Orange from Aqueous Solution by Calcium Alginate/Multi-walled Carbon Nanotubes Composite Fibers

AbstractAdsorbent of calcium alginate/multi-walled carbon nanotubes (CA/MWCNTs) composite fiber was prepared by wet spinning. Adsorptions of methyl orange (MO) anionic dyes onto CA/MWCNTs composite fiber were investigated with respect to MWCNTs content, initial dye concentration and pH values. Results illustrated that introduction of MWCNTs could obviously increase the adsorption capacity (qe) of MO onto CA/MWCNTs composite fibers. The equilibrium adsorption data were analyzed using two widely applied isotherms: Langmuir and Freundlich. The results showed that Langmuir isotherm fitted the experimental results well

Experimental study on the uniaxial compressive behaviour of a fibre reinforced polymer standing support

Laboratory tests were conducted to investigate the behaviour of an innovative fibre reinforced polymer (FRP) standing support subject to uniaxial compression. The FRP standing support consisted of two major components: 1) the internal cylindrical concrete column made of coal rejects and a cementitious grout, and 2) the external FRP jacket. A total of ten specimens with different water-to-cementitious grout (w/c) ratios and various layers of FRP confinement were prepared and tested. As expected, an increased w/c ratio adversely affected the compressive strength of the internal cylindrical column. The compressive strength of the column decreased from 15.9 MPa to 13.4 MPa when the w/c ratio increased from 1 to 1.2. Test results also indicated that the columns became much stronger and more deformable when confined with an FRP jacket. In contrast to the unconfined control specimens, the columns confined with two layers of FRP experienced an increase of approximately 150% in maximum compressive strength at approximately 500% higher axial deformation. A further growth in strength and deformability was also observed when the columns were confined with four layers of FRP. The maximum strength and deformability achieved were up to 49.6 MPa and 7.2% respectively

A lightweight CIR-based CNN with MLP for NLOS/LOS identification in a UWB positioning system

Implementing line-of-sight (LOS) and none-line-of-sight (NLOS) identification in ultra-wideband (UWB) systems is crucial. Convolutional neural network (CNN) based identification methods can extract higher-level features automatically, but they are based on channel impulse response (CIR)-turned image ingested features that impose calculation complexity and do not make use of manual features due to the data inundation risk. In this letter, we propose a novel multilayer perceptron (MLP)-based LOS/NLOS identification algorithm that can utilize both manually extracted features and feature from CNN based on raw CIR inputs with only 7.39% calculation complexity as compared to the traditional image-based CNN. Three experiments, at a teaching building, an office, and an underground mine, were conducted to verify the proposed method’s performance. Our proposed features are conducive to LOS/NLOS identification, especially the proposed raw CIR-based feature from the CNN, achieving 26.9% improvement over existing manual features. Furthermore, the proposed method outperformed the traditional image-based CNN with an improvement of 44.16%

Pre-Construction Progress of Giant Steerable Science Mirror for TMT

The Changchun Institute of Optics, Fine Mechanics and Physics (CIOMP) team is developing the Giant Steerable Science Mirror (GSSM) for Thirty Meter Telescope (TMT) which will enter the preliminary design phase in 2016. The GSSM is the tertiary mirror of TMT and consists of the world’s largest flat telescope mirror (approximately 3.4m X 2.4 m X 100mm thick) having an elliptical perimeter positioned with an extremely smooth tracking and pointing mechanism in a gravity-varying environment. In order to prepare for developing this unique mirror system, CIOMP has been developing a 1/4 scale, functionally accurate version of the GSSM prototype during the pre-construction phase of GSSM. The prototype will incorporate the same optomechanical system and servo control system as the GSSM. The size of the prototype mirror is 898.5mm×634mm×12.5mm with an elliptical perimeter. The mirror will be supported axially by an 18 point whiffletree and laterally with a 12 point whiffletree. The main objective of the preconstruction phase includes requirement validation and risk reduction for GSSM and to increase confidence that the challenge of developing the GSSM can be met. The precision mechanism system and the optical mirror polishing and testing have made good progress. CIOMP has completed polishing the mirror, the prototype mechanism is nearly assembled, some testing has been performed, and additional testing is being planned and prepared. A dummy mirror is being integrated into the cell assembly prototype to verify the design, analysis and interface and will be used when testing the prototype positioner tilt and rotation motions. The prototype positioner tilt and rotator structures have been assembled and tested to measure each subsystem’s jitter and dynamic motion. The mirror prototype has been polished and tested to verify the polishing specification requirement and the mirror manufacturing process. The complete assembly, integration and verification of the prototype will be soon finished. Final testing will verify the prototype requirements including mounted mirror surface figure accuracy in 5 different orientations; rotation and tilt motion calibration and pointing precision; motion jitter; and internally generated vibrations. CIOMP has scheduled to complete the prototype by the end of July 2016. CIOMP will get the sufficient test results during the pre-construction phase to prepare to enter the preliminary design for GSSM