1,714 research outputs found

    Lower Cambrian bioherms in central Nevada and eastern California

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    A comparative sedimentological and paleontological study was made of two approximately coeval Lower Cambrian bioherm complexes, one in the Ravenswood area of Lander County in central Nevada, and the other in the Montenegro Member of the Campito Formation in the White-Inyo Range of eastern California. Although both bioherm complexes were constructed by archaeocyaths and calcareous microbial organisms, there are significant differences in the structure and fabric of the biohermal limestones, in the taxa and diversity of archaeocyaths, and in the diversity of the bioherm community in general. The Ravenswood bioherms developed as framework reefs in a high-energy, normal marine setting and display a relatively high diversity of archaeocyaths and associated organisms, as well as distinct core and flank facies. The Montenegro bioherm complex developed in a restricted, low-energy setting as a mud mound composed of lenticular units (kalyptrae); it contains a lower diversity archaeocyathan fauna and a depauperate fauna of other organisms

    Trace element geochemistry of groundwater flow systems in southern Nevada and eastern California

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    The Nevada Test Site (NTS) was used for underground nuclear tests before the 1960\u27s. Yucca Mountain in southern Nevada has been proposed as the site for the first high-level radioactive waste repository in the U.S. Because groundwater is a likely medium for transporting radio-nuclides to the accessible environment, determining the nature and path of groundwater movement through the aquifers at the NTS and Yucca Mountain is a critical task for assessing the risks and the future performance of the repository. In this study, systematic investigations of major ion and trace [mainly rare earth element (REE)] element geochemistry were conducted on different components of groundwater flow systems in southern Nevada, including groundwaters from representative springs and wells, aquifer rocks that comprise major aquifers, secondary minerals from fractures and veins in the aquifer rocks, and solutions from water/rock interactions. The geochemical data collected in this study help us characterize and compare major ion and REE signatures in different sample media, study changes in trace elements and REEs resulting from water/rock interactions, and develop a geochemical framework to trace groundwater from sources and predict groundwater flow paths and fluid mixing at the Nevada Test Site and the Yucca Mountain region of southern Nevada. The study also enhances our geologic and hydrologic understanding of trace element and REE geochemistry in the groundwater flow systems

    Analysis of significant factors on cable failure using the Cox proportional hazard model

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    This paper proposes the use of the Cox proportional hazard model (Cox PHM), a statistical model, for the analysis of early-failure data associated with power cables. The Cox PHM analyses simultaneously a set of covariates and identifies those which have significant effects on the cable failures. In order to demonstrate the appropriateness of the model, relevant historical failure data related to medium voltage (MV, rated at 10 kV) distribution cables and High Voltage (HV, 110 kV and 220 kV) transmission cables have been collected from a regional electricity company in China. Results prove that the model is more robust than the Weibull distribution, in that failure data does not have to be homogeneous. Results also demonstrate that the method can single out a case of poor manufacturing quality with a particular cable joint provider by using a statistical hypothesis test. The proposed approach can potentially help to resolve any legal dispute that may arise between a manufacturer and a network operator, in addition to providing guidance for improving future practice in cable procurement, design, installations and maintenance

    An oil painters recognition method based on cluster multiple kernel learning algorithm

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    A lot of image processing research works focus on natural images, such as in classification, clustering, and the research on the recognition of artworks (such as oil paintings), from feature extraction to classifier design, is relatively few. This paper focuses on oil painter recognition and tries to find the mobile application to recognize the painter. This paper proposes a cluster multiple kernel learning algorithm, which extracts oil painting features from three aspects: color, texture, and spatial layout, and generates multiple candidate kernels with different kernel functions. With the results of clustering numerous candidate kernels, we selected the sub-kernels with better classification performance, and use the traditional multiple kernel learning algorithm to carry out the multi-feature fusion classification. The algorithm achieves a better result on the Painting91 than using traditional multiple kernel learning directly

    Single-walled carbon nanotube bundle under hydrostatic pressure studied by the first-principles calculations

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    The structural, electronic, optical and vibrational properties of the collapsed (10,10) single-walled carbon nanotube bundle under hydrostatic pressure have been studied by the first-principles calculations. Some features are observed in the present study: First, a collapsed structure is found, which is distinct from both of the herringbone and parallel structures obtained previously. Secondly, a pseudo-gap induced by the collapse appears along the symmetry axis \textit{Γ\Gamma X}. Thirdly, the relative orientation between the collapsed tubes has an important effect on their electronic, optical and vibrational properties, which provides an efficient experimental method to distinguish unambiguously three different collapsed structures.Comment: 14 pages, 6 figure

    Global strong solutions to the compressible Navier-Stokes system with potential temperature transport

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    We study the global strong solutions to the compressible Navier-Stokes system with potential temperature transport in Rn.\mathbb{R}^n. Different from the Navier-Stokes-Fourier system, the pressure is a nonlinear function of the density and the potential temperature, we can not exploit the special quasi-diagonalization structure of this system to capture any dissipation of the density. Some new idea and delicate analysis involved in high or low frequency decomposition in the Besov spaces have to be made to close the energy estimates.Comment: 12page

    N-(Quinolin-8-yl)quinoline-2-carbox­amide

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    In the title compound, C19H13N3O, the dihedral angle between the two quinoline systems is 11.54 (3)°. The mol­ecular conformation is stabilized by intra­molecular N—H⋯N and C—H⋯O hydrogen bonds, with N—H⋯N being bifurcated towards the two N atoms of the two quinoline rings. In the crystal, there are weak intermolecular π–π inter­actions present involving the quinoline rings [centroid–centroid distance 3.7351 (14) Å]
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