804 research outputs found
Energy dissipation in sheared wet granular assemblies
Energy dissipation in sheared dry and wet granulates is considered in the presence of an externally applied confining pressure. Discrete element simulations reveal that for sufficiently small confining pressures, the energy dissipation is dominated by the effects related to the presence of cohesive forces between the particles. The residual resistance against shear can be quantitatively explained by a combination of two effects arising in a wet granulate: (i) enhanced friction at particle contacts in the presence of attractive capillary forces and (ii) energy dissipation due to the rupture and reformation of liquid bridges. Coulomb friction at grain contacts gives rise to an energy dissipation which grows linearly with increasing confining pressure for both dry and wet granulates. Because of a lower Coulomb friction coefficient in the case of wet grains, as the confining pressure increases the energy dissipation for dry systems is faster than for wet ones
Deployment of RDFa, Microdata, and Microformats on the Web – A Quantitative Analysis
More and more websites embed structured data describing for instance
products, reviews, blog posts, people, organizations, events, and cooking recipes
into their HTML pages using markup standards such as Microformats, Microdata
and RDFa. This development has accelerated in the last two years as major Web
companies, such as Google, Facebook, Yahoo!, and Microsoft, have started to
use the embedded data within their applications. In this paper, we analyze the
adoption of RDFa, Microdata, and Microformats across the Web. Our study is
based on a large public Web crawl dating from early 2012 and consisting of 3
billion HTML pages which originate from over 40 million websites. The analysis
reveals the deployment of the different markup standards, the main topical areas
of the published data as well as the different vocabularies that are used within each
topical area to represent data. What distinguishes our work from earlier studies,
published by the large Web companies, is that the analyzed crawl as well as the
extracted data are publicly available. This allows our findings to be verified and to
be used as starting points for further domain-specific investigations as well as for
focused information extraction endeavors
Balanced and Restored Cross-Sections Representing Post-Miocene Crustal Extension of Fluvial Deposits, North-Central Montana to Southeast Idaho
This research is part of a larger project based on the theory of the existence of a pre-ice age, Amazon-scale river that had headwaters in the southern Colorado Plateau and flowed north through the western United States and Canada before discharging into the Labrador Sea. Stream-rounded fluvial deposits in Montana and Idaho provide evidence of sediment provenance in Nevada and Utah, as there are no confirmed bedrock sources for these sediments in Montana or Idaho. The Miocene river bed has been offset and tilted by dozens of extensional faults in the region. Some faults bound large mountain ranges including the Lost River, Lemhi, Beaverhead, Tendoy, Blacktail Deer, Ruby, Madison, and Big Belt Mountains. The reconstructed trend of the Miocene river bed provides a reference line against which to measure active faulting. We constructed five balanced cross-sections of the deformed subsurface along the Miocene river bed from north-central Montana to southeast Idaho across the faulted mountain ranges and restored the cross-sections to represent an un-deformed subsurface. This provided valuable insight into crustal deformation in these regions. Knowing the timing and extent of crustal deformation has many scientific and societal benefits. Western Montana and adjacent Idaho occupy the Inter-mountain Seismic Zone and have the potential for large earthquakes. Detailed cross-sections through this zone can provide information for development projects in faulted areas, and target potential aquifer locations where the thick river gravel has been down-faulted into the sub-surface. This research will be an important contribution to understanding the evolution of the tectonic landscape of Montana and Idaho
First neutron spectroscopy measurements in the ASDEX Upgrade tokamak
Abstract: A compact neutron spectrometer based on the liquid scintil-lator BC501A has been installed on the ASDEX Upgrade tokamak. The aim is to measure neutron energy distribution functions as footprints of fast ions distribution functions, generated mainly via Neutral Beam Injection (NBI) in present day tokamaks. A flexible and fast software has been developed to perform digital pulse shape separation and to evaluate pulse height spectra. First measurements of count rates and pulse height spectra show a good sig-nal to noise ratio for integration times comparable to the NBI slowing down time and to the energy confinement time. Due to the perpendicular line of sight, D-d fusion with perpendicular NBI is detected more efficiently and the line broadening of the 2.45 MeV neutrons is higher. Ion Cyclotron Reso-nance Heating (ICRH) combined to NBI exhibits a synergy effect, with count rates higher than the sum of the counts due to NBI and ICRH separately. Although the collimator is designed to screen gammas as much as possible, some qualitative gamma analysis is also possible, providing information in case of runaway electrons during disruptions. The experimental campaign for the characterisation of the system (detector + acquisition system) is complete and the determination of the response function is in progress.
Direction distributions of neutrons and reference values of the personal dose equivalent in workplace fields
Within the EC project EVIDOS, double-differential (energy and direction) fluence spectra were determined by means of novel direction spectrometers. By folding the spectra with fluence-to-dose equivalent conversion coefficients, contributions to H*(10) for 14 directions, and values of the personal dose equivalent Hp(10) and the effective dose E for 6 directions of a person's orientation in the field were determined. The results of the measurements and calculations obtained within the EVIDOS project in workplace fields in nuclear installations in Europe, i.e., at Krümmel (boiling water reactor and transport cask), at Mol (Venus research reactor and fuel facility Belgonucléaire) and at Ringhals (pressurised reactor and transport cask) are presente
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