3,195 research outputs found

    Evolution of pore structure, submaceral composition and produced gases of two Chinese coals during thermal treatment

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    This research was funded by the Research Program for Excellent Doctoral Dissertation Supervisor of Beijing (grant no. YB20101141501), the Fundamental Research Funds for Central Universities (grant no. 35832015136) and Key Project of Coal-based Science and Technology in Shanxi Province-CBM accumulation model and reservoir evaluation in Shanxi province (grant no. MQ2014-01).Peer reviewedPostprin

    Iterative algorithm for lane reservation problem on transportation network

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    International audienceIn this paper, we study an NP-hard lane reservation problem on transportation network. By selecting lanes to be reserved on the existing transportation network under some special situations, the transportation tasks can be accomplished on the reserved lanes with satisfying the condition of time or safety. Lane reservation strategy is a flexible and economic method for traffic management. However, reserving lanes has impact on the normal traffic because the reserved lanes can only be passed by the special tasks. It should be well considered choosing reserved lanes to minimize the total traffic impact when applying the lane reservation strategy for the transportation tasks. In this paper, an integer linear program model is formulated for the considered problem and an optimal algorithm based on the cut-and-solve method is proposed. Some new techniques are developed for the cut-and-solve method to accelerate the convergence of the proposed algorithm. Numerical computation results of 125 randomly generated instances show that the proposed algorithm is much faster than a MIP solver of commercial software CPLEX 12.1 to find optimal solutions on average computing time

    Differentiated rare-element mineralization in an ongonite − topazite composite dike at the Xianghualing tin district, Southern China: an electron-microprobe study on the evolution from niobium-tantalum-oxides to cassiterite

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    International audienceOur study characterizes in detail the mineralogical, textural and compositional features of a highly evolved, composite ongonite-topazite dike and its magmatic differentiation history. We present compositional data collected by established techniques, i.e. by electron microprobe and wet-chemical analysis, which provide a detailed framework for future studies that employ state-of-the-art analytical techniques. The studied dike (referred to as the No. 431 dike) crops out within the Xianghualing area in the Nanling Range of southern China, in close spatial association with Jurassic Sn-Nb-Ta granite plutons. The rock samples in the No. 431 dike were collected from a structurally lower drill hole and a trench at higher level. The ongonite is encountered throughout the dike, but the topazite is only revealed along the margin of the upper, near-surface dike. The results of whole-rock major and trace element analyses show that the rocks of the No. 431 dike are strongly peraluminous with an average ACNK value of ~ 1.5 for ongonite and > 3.9 for topazite. They are enriched in F, 1.7 wt.% and 5.4 wt.% on average for ongonite and topazite, respectively. The rocks have low Zr/Hf and Nb/Ta ratios, and high levels of ore-forming elements including Nb, Ta, Sn, and W. Silicate and oxide mineral assemblages, textures, and compositions are also distinct for the two rock types studied. In the lower ongonite of the dike, there are abundant phenocrysts of K-feldspar, quartz, and albite, and microphenocrysts of topaz and zinnwaldite in a matrix dominated by quartz, K-feldspar, and albite. Characteristic oxides are columbite-tantalite, tapiolite, and microlite, but cassiterite is absent. The upper ongonite of the dike has a silicate assemblage similar to the lower ongonite; columbite-(Mn), uranomicrolite, and limited amounts of cassiterite are the dominant accessory minerals. The topazite is characterized by large amounts of topaz and zinnwaldite intergrown with quartz, while K-feldspar, albite, and quartz phenocrysts have rounded shapes and are relatively rare. Cassiterite is the most abundant ore mineral, while Nb-Ta oxide minerals are less abundant. We interpret the whole-rock compositional trends, mineral textures, assemblages, and compositions to reflect the differentiation of an evolved, initially homogeneous magma that separated into aluminosilicate and hydrosaline melts, corresponding to crystallization of ongonite and topazite, respectively. The crystallization of Nb-Ta- and Sn-bearing ore minerals was strongly controlled by the separation of the two melt phases. We hypothesize that dike propagation/widening subsequent to the initial dike emplacement may have driven the separation of the aluminosilicate and hydrosaline melt phases that crystallized to ongonite in the core and topazite along the margins of the structurally higher part of the dike

    Bis[2-(1H-benzimidazol-2-yl)benzoato]copper(II) dihydrate

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    In the title compound, [Cu(C14H9N2O2)2]·2H2O, the Cu(II) ion lies on a centre of symmetry and is four-coordinated by two N atoms and two O atoms from two 2-(1H-benzimidazol-2-yl)benzoate ligands in a square-planar environment. The benzimidazol and benzyl rings form a dihedral angle of 42.8 (5)°. The mol­ecule contains two H-bonded carboxyl O acceptors and two H-bonded N—H donors in the benzimidazol groups, which inter­act with two symmetry-related uncoordinated water mol­ecules so that neighboring mol­ecular units are linked by (O—H)water⋯Ocarbox­yl hydrogen bonds with an R 2 4(8) graph-set motif, generating a helical chain in the a-axis direction. These chains are, in turn, inter­connected by (N—H)benzimidazol⋯Owater hydrogen bonds, forming a three-dimensional supra­molecular network
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