Search Results (3)

With the popularity of ground and airborne three-dimensional laser scanning hardware and the development of advanced technologies for computer vision in geometrical measurement, intelligent processing of point clouds has become a hot issue in artificial intelligence. The intervisibility analysis in 3D space can use viewpoint, view distance, and elevation values and consider terrain occlusion to derive the intervisibility between two points. In this study, we first use the 3D point cloud of reflected signals from the intelligent autonomous driving vehicle’s 3D scanner to estimate the field-of-view of multi-dimensional data alignment. Then, the forced metrics of mechanical Riemann geometry are used to construct the Manifold Auxiliary Surface (MAS). With the help of the spectral analysis of the finite element topology structure constructed by the MAS, an innovative dynamic intervisibility calculation is finally realized under the geometric calculation conditions of the Mix-Planes Calculation Structure (MPCS). Different from advanced methods of global and interpolation pathway-based point clouds computing, we have removed the 99.54% high-noise background and reduced the computational complexity by 98.65%. Our computation time can reach an average processing time of 0.1044 s for one frame with a 25 fps acquisition rate of the original vision sensor. The remarkable experimental results and significant evaluations from multiple runs demonstrate that the proposed dynamic intervisibility analysis has high accuracy, strong robustness, and high efficiency. This technology can assist in terrain analysis, military guidance, and dynamic driving path planning, Simultaneous Localization And Mapping (SLAM), communication base station siting, etc., is of great significance in both theoretical technology and market applications. Full article

A new supramolecular Pb(II) complex [PbL(NO₂)]_n was synthesized from Pb(NO₃)₂, N’-(1-(pyridin-2-yl)ethylidene)isonicotinohydrazide (HL) and NaNO₂. [PbL(NO₂)]_n is constructed from discrete [PbL(NO₂)] units with an almost ideal N₂O₃ square pyramidal coordination environment around Pb(II). The ligand L⁻ is coordinated through the 2-pyridyl N-atom, one aza N-atom, and the carbonyl O-atom. The nitrite ligand binds in a κ²-O,O coordination mode through both O-atoms. The Pb(II) center exhibits a hemidirected coordination geometry with a pronounced coordination gap, which allows a close approach of two additional N-atoms arising from the N=C(O) N-atom of an adjacent molecule and from the 4-pyridyl N-atom from the another adjacent molecule, yielding a N₄O₃ coordination, constructed from two Pb–N and three Pb–O covalent bonds, and two Pb⋯N tetrel bonds. Dimeric units in the structure of [PbL(NO₂)]_n are formed by the Pb⋯N=C(O) tetrel bonds and intermolecular electrostatically enforced π⁺⋯π⁻ stacking interactions between the 2- and 4-pyridyl rings and further stabilized by C–H⋯π intermolecular interactions, formed by one of the methyl H-atoms and the 4-pyridyl ring. These dimers are embedded in a 2D network representing a simplified uninodal 3-connected fes (Shubnikov plane net) topology defined by the point symbol (4∙8²). The Hirshfeld surface analysis of [PbL(NO₂)] revealed that the intermolecular H⋯X (X = H, C, N, O) contacts occupy an overwhelming majority of the molecular surface of the [PbL(NO₂)] coordination unit. Furthermore, the structure is characterized by intermolecular C⋯C and C⋯N interactions, corresponding to the intermolecular π⋯π stacking interactions. Notably, intermolecular Pb⋯N and, most interestingly, Pb⋯H interactions are remarkable contributors to the molecular surface of [PbL(NO₂)]. While the former contacts are due to the Pb⋯N tetrel bonds, the latter contacts are mainly due to the interaction with the methyl H-atoms in the π⋯π stacked [PbL(NO₂)] molecules. Molecular electrostatic potential (MEP) surface calculations showed marked electrostatic contributions to both the Pb⋯N tetrel bonds and the dimer forming π⁺⋯π⁻ stacking interactions. Quantum theory of atoms in molecules (QTAIM) analyses underlined the tetrel bonding character of the Pb⋯N interactions. The manifold non-covalent interactions found in this supramolecular assembly are the result of the proper combination of the polyfunctional multidentate pyridine-hydrazide ligand and the small nitrito auxiliary ligand. Full article

The hydrological monitoring of springs is an auxiliary and indispensable tool that goes alongside investigations in wells to reconstruct a conceptual phenomenological model of an aquifer–groundwater system and its interactions with surface waters. There are manifold ways to carry out this monitoring, but the choice of which way is significant for a correct qualitative and quantitative knowledge of spring systems. The present work focuses on the characterization of the thermo-saline and flow regimes of the Tara spring system along the northern coast of Taranto (southern Italy), where a karst groundwater basin is the major source of the Tara River and the surrounding coastal wetland. A series of measurements was carried out on the spring system to support a technical feasibility study on the possible use of the brackish water of this river to feed a future desalination plant. To estimate the flow rate, a comparison was made between different flow measurement methods in a derivation channel. Through an analysis of the available dataset, the response of the aquifer to the autumn–winter recharge, for which updated hydrologic measurements were not available, is highlighted. Full article