1,721,984 research outputs found
A maximal function characterisation of absolutely continuous measures and Sobolev functions
No full textIn this note, we give a new characterisation of Sobolev W1; 1 functions among BV functions via Hardy-Littlewood maximal function. Exploiting some ideas coming from the proof of this result, we are also able to give a new characterisation of absolutely continuous measures via a weakened version of Hardy-Littlewood maximal function. Finally, we show that the approach adopted in [3, 8] to establish existence and uniqueness of regular Lagrangian flows associated to Sobolev vector fields cannot be further extended to the case of BV vector fields
Monitoring of self-annealing in ultrafine-grained silver using nanoindentation
No full textThe self-annealing of an ultrafine-grained (UFG) microstructure in pure silver produced by severe plastic deformation (SPD) was studied by nanoindentation and X-ray line profile analysis. Both recovery and recrystallization of the UFG structure take place during long-term storage at room temperature as a result of the extremely high dislocation density which acts as a driving force in self-annealing. Nanohardness mapping revealed that self-annealing occurred inhomogeneously, and the higher strain imposed in SPD processing leads to faster recrystallization in severely deformed silver. This behavior of self-annealing can be explained by the enhanced contribution of twinning which facilitates the formation of recrystallized embryos
Effect of density difference between the solids and suspending liquid on the rheological properties of setting slurries
No full textPlastic behavior of fcc metals over a wide range of strain: macroscopic and microscopic descriptions and their relationship
No full textThe room temperature macroscopic and microscopic plastic behavior of four face-centered cubic metals (Al, Au, Cu and Ni) is investigated experimentally over a wide strain range, and theoretical modeling is used to simulate the established major micromechanisms describing the evolution of mobile and forest dislocations during plastic flow. It is shown that forest dislocations develop primarily due to interaction between mobile dislocations, while the contribution from forest–mobile interactions is only minor. The trapping of mobile dislocations and the annihilation of forest dislocations are both controlled by the same thermally activated dislocation motion. These observations permit a simplification of the theoretical model that leads to an analytical relationship for the evolution of the total dislocation density as a function of strain. From this analysis, correlations are drawn between the macroscopic parameters describing the stress–strain relationship and the fundamental characteristics of the microscopic processe
Plastic behavior of face-centered-cubic metals over a wide range of strain
No full textThe plastic behavior of four pure face-centered-cubic (fcc) metals (Al, Au, Cu and Ni) was studied at room temperature up to a strain value of 8 achieved by severe plastic deformation. It is shown that at high strains the saturation flow stress and the total dislocation density can be scaled with the melting point, and the deformation process can be regarded as steady-state flow leading to a uniform description of the plastic behavior of these fcc metals at all temperatures. The results suggest that the plastic flow at room temperature of fcc metals processed by severe deformation is primarily attributable to diffusion-controlled and thermally activated processes due to the high concentration of deformation-induced vacancies.<br/
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
New Betweenness Centrality Node Attack Strategies for Real-World Complex Weighted Networks
Full text linkIn this work, we introduce a new node attack strategy removing nodes with the highest conditional weighted betweenness centrality (CondWBet), which combines the weighted structure of the network and the node's conditional betweenness. We compare its efficacy with well-known attack strategies from literature over five real-world complex weighted networks. We use the network weighted efficiency (WEFF) like a measure encompassing the weighted structure of the network, in addition to the commonly used binary-topological measure, i.e., the largest connected cluster (LCC). We find that if the measure is WEFF, the CondWBet strategy is the best to decrease WEFF in 3 out of 5 cases. Further, CondWBet is the most effective strategy to reduce WEFF at the beginning of the removal process, whereas the Strength that removes nodes with the highest sum of the link weights first shows the highest efficacy in the final phase of the removal process when the network is broken into many small clusters. These last outcomes would suggest that a better attacking in weighted networks strategy could be a combination of the CondWBet and Strength strategies
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