Room segmentation is a basic task for the semantic enrichment of point clouds. Recent studies have mainly projected single-floor point clouds to binary images to realize two-dimensional room ...segmentation. However, these methods have difficulty solving semantic segmentation problems in complex 3D indoor environments, including cross-floor spaces and rooms inside rooms; this is the bottleneck of indoor 3D modeling for non-Manhattan worlds. To make full use of the abundant geometric and spatial structure information in 3D space, a novel 3D room segmentation method that realizes room segmentation directly in 3D space is proposed in this study. The method utilizes volumetric representation based on a VDB data structure and packs an indoor space with a set of compact spheres to form rooms as separated connected components. Experimental results on different types of indoor point cloud datasets demonstrate the efficiency of the proposed method.
Traffic congestion in expressway networks has a strong negative influence on regional development. Understanding the spatiotemporal patterns of traffic congestion in expressway networks is critical ...for improving the exchange of products in regional production and promoting regional economic development. Nevertheless, existing studies pay less attention to these spatiotemporal patterns of traffic congestion. Considering that Origin–Destination (OD) data are available for the recorded spatial movements of vehicles in expressways, this study proposes a method with which to explore traffic congestion at the level of road segments in the regional expressway network, the mainstream of driving behaviors, and traffic regulations. Methods for analyzing spatial disparity and temporal changes in traffic congestion in expressway networks are also put forward in this paper. The empirical results show that the proposed methods could detect road segments where traffic congestion happens, and then uncover temporal patterns of several congested locations and spatial patterns of road segments with frequent congestion. These spatiotemporal patterns of traffic congestion could be in accord with the actual situation. This study provides a new approach to investigating traffic congestion in expressway networks based on low-cost data, which might be helpful for optimizing expressway network planning and promoting balanced regional development.
The glycopeptidase GCP and its homologue proteins are conserved and essential for survival of bacteria. The
gene (Glycopeptidase homologue) was cloned from
strain SF-1. The gene consisted of 1,017 ...bp, which encodes a 338 amino acid polypeptide. The nucleotide sequence similarity of the
gene with that of
FDAARGOS 107 was 95%. The
gene also showed similarities of 68%, 67% and 50% with those of
,
and
. The
gene was expressed in
BL21 (DE3) and the recombinant YgjD was purified by Ni
affinity chromatography column. The purified YgjD showed a specific 37 kDa band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and exhibited protease activities of 59,000 units/mg, 53,700 units/mg and 8,100 units/mg, respectively, on N-Acetyl-L-tyrosine ethyl ester monohydrate (ATEE), N-Benzoyl-L-tyrosine ethyl ester (BTEE) and N-Benzoyl-DL-arginine-4-nitroanilide hydrochloride (BAPNA) substrates. When the conserved amino acids of His
, Glu
and His
in the YgjD were replaced with alanine, respectively, the protease activities of the mutants were partly decreased. The two conserved His
and His
of YgjD were mutated and the protein lost the protease activity, which implied that the two amino acid played very important roles in maintaining its protease activity. The addition of the purified YgjD to the culture medium of
strain SF-1 can effectively promote the bacteria growth. These results indicated that the protease activities may be involved in the survival of bacteria.
Topological models in Euclidean space are difficult for spatial analysis because of the lack of direct representation of geometric three-dimensional (3D) object information. A 3D cadastral data model ...in the form of boundary representation based on conformal geometric algebra (CGA) is proposed to realize the integrated representation of geometric and topological information based on previous research. On the basis of the 3D cadastral data model based on CGA and basic geometric operators, self-defined geometric algebraic operators are designed using the advantages of geometric algebra in spatial topological calculation. A computation framework for cadastral parcel topological error detection is put forward based on those self-defined geometric operators. A case study is designed to verify the feasibility of topological error detection methods proposed in this paper. This study is an expansion of research for a 3D cadastral data model based on CGA.
Vertex concavity-convexity detection for spatial objects is a basic algorithm of computer graphics, as well as the foundation for the implementation of other graphics algorithms. In recent years, the ...importance of the vertex concavity-convexity detection algorithm for three-dimensional (3D) spatial objects has been increasingly highlighted, with the development of 3D modeling, artificial intelligence, and other graphics technologies. Nonetheless, the currently available vertex concavity-convexity detection algorithms mostly use two-dimensional (2D) polygons, with limited research on vertex concavity-convexity detection algorithms for 3D polyhedrons. This study investigates the correlation between the outer product and the topology of the spatial object based on the unique characteristic that the outer product operation in the geometric algebra has unified and definitive geometric implications in space, and with varied dimensionality. Moreover, a multi-dimensional unified vertex concavity-convexity detection algorithm framework for spatial objects is proposed, and this framework is capable of detecting vertex concavity-convexity for both 2D simple polygons and 3D simple polyhedrons.
Maintaining topological consistency is a crucial issue for 3D cadastral modeling as this helps to represent the cadastral boundary clearly and accurately. As a result, 3D cadastral data models are ...mainly built on the basis of topological models that allow topology to be expressed clearly. However, topological models in Euclidean space cannot directly represent objects’ geometric information. As geometric information is important in 3D spatial analysis, 3D cadastral data models based on topological models cannot realize topological calculation and analysis. Previous research has proved that geometric and topological information for cadastral objects can be integrated and represented by conformal geometric algebra (CGA) expressions. This paper aims to realize 3D topological analysis in the cadastral field using CGA’s advantages in geometric relations computation. A calculation framework is designed on the basis of the outer product to achieve the purpose of multidimensional unity for 3D cadastral topological analysis in this paper. A calculation framework of topological relations between a boundary point (or a boundary line) and a cadastral parcel is developed. A total of 13 types of topological relations between a boundary point and a cadastral parcel and 48 types of topological relations between a boundary line and a cadastral parcel are obtained. The study indicates that the advantages of CGA in multidimensional unified representation and calculation can be used to solve problems encountered by topological models in Euclidean space.
The confined meso-Pt/CeO2 catalyst showed excellent performance for the catalytic oxidation of toluene. It is verified that the double-layer confinement effect of ordered mesoporous SBA-15 and Ce-MOF ...effectively play a significant key in avoiding the migration and aggregation of Pt nanoparticles in the reaction process, improving the dispersion of Pt, enhancing the interface effect between Pt and CeO2, and improving the low-temperature catalytic activity and thermal stability of toluene oxidation.
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•The Pt/Ce-MOF was successfully anchored in the channels of ordered mesoporous SBA-15.•Double-layer confinement effect of ordered mesoporous SBA-15 and Ce-MOF was proposed.•The confined meso-Pt/CeO2 catalyst showed excellent performance for toluene oxidation.•In situ SERS show that oxygen molecules are activated as Ce-O and Pt-O active species.
In this study, the confined Pt/Ce-MOF were for the first time synthesized using an in-situ vacuum self-assembly strategy. It is confirmed that the meso-Pt/CeO2 catalyst derived from the confined Pt/Ce-MOF has excellent activity and stability in the catalytic oxidation of toluene, which is mainly due to the effective anchoring of Pt nanoparticles in Ce-MOF, and the interface effect between Pt nanoparticles and CeO2. More importantly, it is discovered that the double-layer confinement effect of ordered mesoporous SBA-15 and Ce-MOF can effectively avoid the migration and aggregation of Pt nanoparticles, making meso-Pt/CeO2 catalysts exhibit higher Pt dispersion. The structure-activity relationship and reaction mechanism of the meso-Pt/CeO2 catalyst were explored by in situ surface-enhanced Raman spectroscopy (SERS) and in situ DRIFTs spectra. The results show that oxygen molecules in the air are firstly adsorbed to the surface of the catalyst, and then are activated as Ce-O and Pt-O active species during the reaction process. The benzyl alcohol, benzoic acid, benzoate and maleic anhydride are the main intermediate products, indicating that the reaction pathway may be as follows: adsorption of toluene → benzyl alcohol → benzoic acid → benzoate → maleic anhydride → … → carbon dioxide and water. Simultaneously, it is verified that the benzyl alcohol (C6H5CH2O) and carboxylic acid species is the decisive step in the oxidation of toluene on basis of in situ SERS and DRIFTs spectra.
The application of a 3-D topology to cadasters is becoming increasingly important as 3-D cadasters continue to develop and cadastral data applications increase. This study discusses spatial ...topological relations related to 3-D cadasters, the geometric objects used in 3-D cadastral spatial modelling, and the characteristics of the spatial data. The characteristics of the topological relations for a 3-D cadaster are summarized, and a classification method is proposed. Research on the classification of topological spatial relations in 3-D cadasters provides guidance for the analysis and computation of the topological spatial relations, changing of cadastral parcels, and topological consistency in cadastral spatial data.
Configuring Co-based catalysts with excellent activity, durability, anti-H2O capability and superior chlorine resistance is an effective strategy for catalytic combustion of CVOCs. In this work, we ...elaborated a CoCuOx catalysts with the same core but different shell. The CoCuOx dodecahedron surface was successfully coated with shells of Nb2O5, TiO2, and CeO2 using a range of conventional synthesis methods. The prepared core-shell catalysts (CoCuOx@TiO2 and CoCuOx@Nb2O5) were found to generate plentiful acid sites and abundant lattice oxygen species, indicating a strong interaction between the core and shell layers that resulted in a significant enhancement of catalytic activity. Additionally, by-products generation was successfully controlled by acid sites and lattice oxygen species. More importantly, the core-shell structure design significantly improved the thermal stability and anti-H2O capability of the catalysts. Furthermore, the possible formation pathways and reaction mechanisms were proposed based on in-situ FTIR and selectivity analysis.
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•The CoCuOx@MOx catalysts shows superior catalytic performance for CVOC elimination.•CoCuOx@TiO2 shows a high thermal stability and excellent Cl and H2O tolerance.•Strong acid sites and lattice oxygen are important for the elimination of CVOCs.•Interaction of the core-shell structure has been explored for catalytic efficiency.
In this work, the mechanism of Ca poisoning on V2O5-WO3/TiO2 catalyst was analyzed. The results showed that CaO not only reacted with SO2 to form CaSO4, which blocked the partial active sites, but ...also destroyed the dispersion of WO3 and formed CaWO4. The presence of CaWO4 could reduce the amount of medium strong and strong acids, thus inhibiting the SCR process.
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•The reducibility of V5+ decreased distinctly after CaO doping.•After CaO poisoning, WO3 was partially converted to crystallized CaWO4.•The surface acidity and redox performance decreased on Ca poisoning catalysts.•Less nitrate intermediates were produced on 5 % CaO VWT, making it difficult to perform “fast SCR” reaction.
Currently, Ca poisoning of the SCR catalyst was the main cause of deactivation in cement kilns. The mechanism of calcium poisoning is rarely studied. In this paper, a series of Ca poisoned V2O5-WO3/TiO2 catalysts were simulated and studied in detailed. As the NH3-SCR results showed, the NO conversion of Fresh VWT was 97.6 % at 280 °C, and decreased to 65 % when 5 % CaO was added. As the CaO content continued to increase, the NO conversion of the catalysts decreased gradually and the catalysts showed worse H2O and SO2 resistance. For a detailed understanding of the poisoning mechanism, the fresh and poisoning VWT were analyzed by using XRD, Raman, XPS, H2-TPR, NH3-TPD and in-situ DRIFTs. It was discovered that CaO not only reacted with SO2 to form CaSO4, which blocked the partial active sites, but also destroyed the dispersion of WO3 and formed CaWO4. The presence of CaWO4 could reduce the amount of medium strong and strong acids, thus inhibiting the SCR process. In-situ DRIFTs experiments showed that less nitrate intermediates were produced on 5 % CaO VWT, making it difficult to perform “fast SCR” reaction.
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