375 research outputs found
Spectral radius conditions for fractional -covered graphs
A graph is called fractional -covered if for every edge of
there is a fractional -factor with the indicator function such that
. In this paper, we provide tight spectral radius conditions for graphs
being fractional -covered.Comment: 9 page
Does the Dirac Cone Exist in Silicene on Metal Substrates?
Absence of the Dirac cone due to a strong band hybridization is revealed to
be a common feature for epitaxial silicene on metal substrates according to our
first-principles calculations for silicene on Ir, Cu, Mg, Au, Pt, Al, and Ag
substrates. The destroyed Dirac cone of silicene, however, can be effectively
restored with linear or parabolic dispersion by intercalating alkali metal
atoms between silicene and the metal substrates, offering an opportunity to
study the intriguing properties of silicene without further transfer of
silicene from the metal substrates
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Mechanism of Exact Transition between Cationic and Anionic Redox Activities in Cathode Material Li2FeSiO4.
The discovery of anion redox activity is promising for boosting the capacity of lithium ion battery (LIB) cathodes. However, fundamental understanding of the mechanisms that trigger the anionic redox is still lacking. Here, using hybrid density functional study combined with experimental soft X-ray absorption spectroscopy (sXAS) measurements, we unambiguously proved that Li(2- x)FeSiO4 performs sequent cationic and anionic redox activity through delithiation. Specifically, Fe2+ is oxidized to Fe3+ during the first Li ion extraction per formula unit (f.u.), while the second Li ion extraction triggered the oxygen redox exclusively. Cationic and anionic redox result in electron and hole polaron states, respectively, explaining the poor conductivity of Li(2- x)FeSiO4 noted by previous experiments. In contrast, other cathode materials in this family exhibit diversity of the redox process. Li2MnSiO4 shows double cationic redox (Mn2+-Mn4+) during the whole delithiation, while Li2CoSiO4 shows simultaneous cationic and anionic redox. The present finding not only provides new insights into the oxygen redox activity in polyanionic compounds for rechargeable batteries but also sheds light on the future design of high-capacity rechargeable batteries
Five-Tiered Route Planner for Multi-AUV Accessing Fixed Nodes in Uncertain Ocean Environments
This article introduces a five-tiered route planner for accessing multiple
nodes with multiple autonomous underwater vehicles (AUVs) that enables
efficient task completion in stochastic ocean environments. First, the
pre-planning tier solves the single-AUV routing problem to find the optimal
giant route (GR), estimates the number of required AUVs based on GR
segmentation, and allocates nodes for each AUV to access. Second, the route
planning tier plans individual routes for each AUV. During navigation, the path
planning tier provides each AUV with physical paths between any two points,
while the actuation tier is responsible for path tracking and obstacle
avoidance. Finally, in the stochastic ocean environment, deviations from the
initial plan may occur, thus, an auction-based coordination tier drives online
task coordination among AUVs in a distributed manner. Simulation experiments
are conducted in multiple different scenarios to test the performance of the
proposed planner, and the promising results show that the proposed method
reduces AUV usage by 7.5% compared with the existing methods. When using the
same number of AUVs, the fleet equipped with the proposed planner achieves a
6.2% improvement in average task completion rate
Motion-Scenario Decoupling for Rat-Aware Video Position Prediction: Strategy and Benchmark
Recently significant progress has been made in human action recognition and
behavior prediction using deep learning techniques, leading to improved
vision-based semantic understanding. However, there is still a lack of
high-quality motion datasets for small bio-robotics, which presents more
challenging scenarios for long-term movement prediction and behavior control
based on third-person observation. In this study, we introduce RatPose, a
bio-robot motion prediction dataset constructed by considering the influence
factors of individuals and environments based on predefined annotation rules.
To enhance the robustness of motion prediction against these factors, we
propose a Dual-stream Motion-Scenario Decoupling (\textit{DMSD}) framework that
effectively separates scenario-oriented and motion-oriented features and
designs a scenario contrast loss and motion clustering loss for overall
training. With such distinctive architecture, the dual-branch feature flow
information is interacted and compensated in a decomposition-then-fusion
manner. Moreover, we demonstrate significant performance improvements of the
proposed \textit{DMSD} framework on different difficulty-level tasks. We also
implement long-term discretized trajectory prediction tasks to verify the
generalization ability of the proposed dataset.Comment: Rat, Video Position Predictio
Silicene Nanomesh
Similar to graphene, zero band gap limits the application of silicene in
nanoelectronics despite of its high carrier mobility. By using first-principles
calculations, we reveal that a band gap is opened in silicene nanomesh (SNM)
when the width W of the wall between the neighboring holes is even. The size of
the band gap increases with the reduced W and has a simple relation with the
ratio of the removed Si atom and the total Si atom numbers of silicene. Quantum
transport simulation reveals that the sub-10 nm single-gated SNM field effect
transistors show excellent performance at zero temperature but such a
performance is greatly degraded at room temperature
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