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21.
Study of Dominant Factors Affecting Cerchar Abrasivity Index 总被引:2,自引:1,他引:1
Jamal Rostami Amireza Ghasemi Ehsan Alavi Gharahbagh Cihan Dogruoz Filip Dahl 《Rock Mechanics and Rock Engineering》2014,47(5):1905-1919
The Cerchar abrasion index is commonly used to represent rock abrasion for estimation of bit life and wear in various mining and tunneling applications. Although the test is simple and fast, there are some discrepancies in the test results related to the equipment used, condition of the rock surface, operator skills, and procedures used in conducting and measuring the wear surface. This paper focuses on the background of the test and examines the influence of various parameters on Cerchar testing including pin hardness, surface condition of specimens, petrographical and geomechanical properties, test speed, applied load, and method of measuring wear surface. Results of Cerchar tests on a set of rock specimens performed at different laboratories are presented to examine repeatability of the tests. In addition, the preliminary results of testing with a new device as a potential alternative testing system for rock abrasivity measurement are discussed. 相似文献
22.
Roeland Boeters Filip Biljecki Sisi Zlatanova 《International journal of geographical information science》2013,27(12):2248-2268
The international standard CityGML defines five levels of detail (LODs) for 3D city models, but only the highest of these (LOD4) supports modelling the indoor geometry of a building, which must be acquired in correspondingly high detail and therefore at a high cost. Whereas simple 3D city models of the exterior of buildings (e.g. CityGML LOD2) can be generated largely automatically, and are thus now widely available and have a great variety of applications, similarly simple models containing their indoor geometries are rare.In this paper we present two contributions: (i) the definition of a level of detail LOD2+, which extends the CityGML LOD2 specification with indoor building geometries of comparable complexity to their exterior geometries in LOD2; and more importantly (ii) a method for automatically generating such indoor geometries based on existing CityGML LOD2 exterior geometries. We validate our method by generating LOD2+ models for a subset of the Rotterdam 3D data set and visually comparing these models to their real counterparts in building blueprints and imagery from Google Street View and Bing Maps. Furthermore, we use the LOD2+ models to compute the net internal area of each dwelling and validate our results by comparing these values to the ones registered in official government data sets. 相似文献
23.
24.
Despite advances in cartography, mapping is still a costly process which involves a substantial amount of manual work. This article presents a method for automatically deriving road attributes by analyzing and mining movement trajectories (e.g. GPS tracks). We have investigated the automatic extraction of eight road attributes: directionality, speed limit, number of lanes, access, average speed, congestion, importance, and geometric offset; and we have developed a supervised classification method (decision tree) to infer them. The extraction of most of these attributes has not been investigated previously. We have implemented our method in a software prototype and we automatically update the OpenStreetMap (OSM) dataset of the Netherlands, increasing its level of completeness. The validation of the classification shows variable levels of accuracy, e.g. whether a road is a one‐ or a two‐way road is classified with an accuracy of 99%, and the accuracy for the speed limit is 69%. When taking into account speed limits that are one step away (e.g. 60 km/h instead of the classified 50 km/h) the classification increases to 95%, which might be acceptable in some use‐cases. We mitigate this with a hierarchical code list of attributes. 相似文献
25.
Andreas F. Hofmann Karline Soetaert Jack J. Middelburg Filip J. R. Meysman 《Aquatic Geochemistry》2010,16(4):507-546
AquaEnv
is an integrated software package for aquatic chemical model generation focused on ocean acidification and antropogenic CO2 uptake. However, the package is not restricted to the carbon cycle or the oceans: it calculates, converts, and visualizes
information necessary to describe pH, related CO2 air–water exchange, as well as aquatic acid–base chemistry in general for marine, estuarine or freshwater systems. Due to
the fact that it includes the relevant acid–base systems, it can also be applied to pore water systems and anoxic waters.
AquaEnv
is implemented in the open source programming language
R
, which allows for a flexible and versatile application:
AquaEnv
’s functionality can be used stand-alone as well as seamlessly integrated into reactive-transport models in the
R
modelling environment. Additionally,
AquaEnv
provides a routine to simulate and investigate titrations of water samples with a strong acid or base, as well as a routine
that allows for a determination of total alkalinity and total carbonate values from recorded titration curves using non-linear
curve-fitting. 相似文献
26.
Tracing an Intra-montane Fault: An Interdisciplinary Approach 总被引:1,自引:0,他引:1
This paper presents the results of combined geophysical and morphostructural research of a significant tectonic lineament forming the boundary between the core Bohemian Forest (?umava) Mts. and its foothills of Po?umaví. The exact course, length and character of the fault have not yet been studied in detail despite its possible role in the uplift of the mountain range. To assess the fault course, length and continuity, we have employed a combination of geophysical, morphological and morphostructural methods. These indirect methods had to be applied as the fault only rarely outcrops along its course, and the morphological border is not straightforward. In the beginning, GIS morphometric methods have been applied to assess the influence of the fault on the present relief. Thereafter, structural measurements of joint systems were undertaken together with the analyses of linear structures within the relief. Finally, resistivity profiling at multiple sites across its estimated course has helped to localise the exact position of the fault. Altogether, fifteen profiles were measured using pole-dipole and dipole–dipole electrode configurations. To obtain more detailed results, the resistivity profiling was supplemented by electrical resistivity tomography on three profiles. The paper brings two main results. Firstly, the combination of morphostructural and geophysical methods brings information that each separately cannot, particularly when the faults have no outcrops. Secondly, it was found that the studied fault stretches along the whole study area. Moreover, indicators point to its possible continuation towards the south-east. 相似文献
27.
Jan Kocum Filip Oulehle Bohumír Janský František Bůzek Jakub Hruška Lukáš Vlček 《水文科学杂志》2013,58(14):2579-2589
ABSTRACTA geochemical approach using stable oxygen isotopes was used to understand streamflow generation processes in the highly peaty catchment of the Rokytka Brook in the headwaters of the Vltava River, Czech Republic. The contribution of water from peat bog areas to the total surface runoff was assessed using a hydrological time series, as well as geochemical, hydrochemical and isotope-hydrological approaches for unit hydrogram separation by means of anion deficiency. Using data from the hydrological year 2008, the role of an existing peat bog in the runoff formation dynamics of the Rokytka Brook catchment was determined, and the hydrological cycle was described and assessed using stable 18O/16O isotopes. The research findings strongly support the fact that peatland areas within the studied catchment do not significantly communicate hydraulically with surface streams, and their hydrological function in this region is insignificant.
Editor M. C. Acreman; Associate editor not assigned 相似文献
28.
Morphodynamics in sand‐bed braided rivers are associated with simultaneous evolution of mid‐channel bars and channels on the braidplain. Bifurcations around mid‐channel bars are key elements that divide discharge and sediment. This, in turn, may control the evolution of connected branches, with effects propagating to both upstream and downstream bifurcations. Recent works on bifurcation stability and development hypothesize major roles of secondary flow and gradient advantage. However, this has not been tested for channel networks within a fully developed dynamic braided river. A reason for this is a lack of detailed measurements with sufficient temporal and spatial length, covering multiple bifurcations. Therefore we used a physics‐based numerical model to generate a dataset of bathymetry, flow and sediment transport of an 80 km river reach with self‐formed braid bars and bifurcations. The study shows that bar dissection due to local transverse water surface gradients is the dominant bifurcation initiation mechanism, although conversion of unit bars into compound bars dominates in the initial stage of a braided river. Several bifurcation closure mechanisms are equally important. Furthermore, the study showed that nodal point relations for bifurcations are unable to predict short‐term bifurcation evolution in a braided river. This is explained by occurrence of nonlinear processes and non‐uniformity within the branches, in particular migrating bars and larger‐scale backwater‐effects, which are not included in the nodal point relations. Planform morphology, on the other hand, has predictive capacity: bifurcation angle asymmetry and bar‐tail limb shape are indicators for near‐future bifurcation evolution. Remote sensing data has predictive value, for which we developed a conceptual model for interactions between bars, bifurcations and channels in the network. We conducted a preliminary test of the conceptual model on satellite images of the Brahmaputra. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
29.
Highly restricted gene flow between disjunct populations of the skunk clownfish (Amphiprion akallopisos) in the Indian Ocean 下载免费PDF全文
The skunk clownfish (Amphiprion akallopisos) has a disjunct distribution, occurring in the Eastern Indian Ocean (EIO) and the Western Indian Ocean (WIO), separated by several thousands of kilometres. Information on connectivity of marine species is very important for the correct spacing of marine protected areas, a powerful instrument for the protection of coral reefs. The population genetic structure of A. akallopisos was analysed in order to investigate connectivity amongst populations and to explain the disjunct distribution of the species. A fragment of the mitochondrial control region was used to investigate the genetic population structure. Fin clips were collected from 263 individuals at 14 sites in the WIO and three sites in the EIO. The obtained DNA sequences were used to calculate genetic diversity, evaluate demographic history and to construct a haplotype network. An analysis of molecular variance (AMOVA) was conducted to evaluate the significance of the observed genetic population structure. None of the identified 69 haplotypes was shared between the WIO and EIO. Haplotype as well as nucleotide diversity was considerably higher in the EIO than in the WIO. Significant genetic population structure was revealed by an AMOVA with an overall φst‐value of 0.28 (P < 0.001) in the Indian Ocean. The overall AMOVA (φst = ?0.00652) was not significant in the EIO, but was significant in the WIO (φst = 0.016; P < 0.01). Demographic analysis indicated population expansion in the EIO and WIO. Population genetic analysis revealed highly restricted gene flow between the EIO and WIO. Genetic diversity was much higher in the EIO than in the WIO, suggesting that the EIO is the geographical origin of the species. Given the large distance between the disjunct populations and the short pelagic larval duration, long‐distance dispersal is rather unlikely. A stepping stone model involving islands in the Central Indian Ocean is a more likely scenario for colonization of the WIO. 相似文献
30.
Dörr Wolfgang Zulauf Gernold Gerdes Axel Loeckle Filip 《International Journal of Earth Sciences》2017,106(8):2927-2943
International Journal of Earth Sciences - Detrital zircons separated from paragneisses of the northern Böllstein Odenwald (Mid-German Crystalline Zone, Variscides) yielded Cambrian to Upper... 相似文献