5,191 research outputs found
Research and Implement of an Algorithm for Physical Topology Automatic Discovery in Switched Ethernet
AbstractIn this paper, a novel practical algorithmic solution for automatic discovering the physical topology of switched Ethernet was proposed. Our algorithm collects standard SNMP MIB information that is widely supported in modern IP networks and then builds the physical topology of the active network. We described the relative definitions, system model and proved the correctness of the algorithm. Practically, the algorithm was implemented in our visualization network monitoring system. We also presented the main steps of the algorithm, core codes and running results on the lab network. The experimental results clearly validate our approach, demonstrating that our algorithm is simple and effective which can discover the accurate up-to-date physical network topology
Implicit Obstacle Map-driven Indoor Navigation Model for Robust Obstacle Avoidance
Robust obstacle avoidance is one of the critical steps for successful
goal-driven indoor navigation tasks.Due to the obstacle missing in the visual
image and the possible missed detection issue, visual image-based obstacle
avoidance techniques still suffer from unsatisfactory robustness. To mitigate
it, in this paper, we propose a novel implicit obstacle map-driven indoor
navigation framework for robust obstacle avoidance, where an implicit obstacle
map is learned based on the historical trial-and-error experience rather than
the visual image. In order to further improve the navigation efficiency, a
non-local target memory aggregation module is designed to leverage a non-local
network to model the intrinsic relationship between the target semantic and the
target orientation clues during the navigation process so as to mine the most
target-correlated object clues for the navigation decision. Extensive
experimental results on AI2-Thor and RoboTHOR benchmarks verify the excellent
obstacle avoidance and navigation efficiency of our proposed method. The core
source code is available at https://github.com/xwaiyy123/object-navigation.Comment: 9 pages, 7 figures, 43 references. This paper has been accepted for
ACM MM 202
Radial Angular Momentum Transfer and Magnetic Barrier for Short-Type Gamma-Ray Burst Central Engine Activity
Soft extended emission (EE) following initial hard spikes up to 100 seconds
was observed with {\em Swift}/BAT for about half of short-type gamma-ray bursts
(SGRBs). This challenges the conversional central engine models of SGRBs, i.e.,
compact star merger models. In the framework of the black hole-neutron star
merger models, we study the roles of the radial angular momentum transfer in
the disk and the magnetic barrier around the black hole for the activity of
SGRB central engines. We show that the radial angular momentum transfer may
significantly prolong the lifetime of the accretion process and multiple
episodes may be switched by the magnetic barrier. Our numerical calculations
based on the models of the neutrino-dominated accretion flows suggest that the
disk mass is critical for producing the observed EE. In case of the mass being
, our model can reproduce the observed timescale and
luminosity of both the main and EE episodes in a reasonable parameter set. The
predicted luminosity of the EE component is lower than the observed EE with
about one order of magnitude and the timescale is shorter than 20 seconds if
the disk mass being . {\em Swift}/BAT-like instruments may
be not sensitive enough to detect the EE component in this case. We argue that
the EE component would be a probe for merger process and disk formation for
compact star mergers.Comment: 9 pages, 3 figures, accepted for publication in Ap
Dimethyl 9-benzyl-3-cyano-9H-pyrrolo[1,2-a]benzimidazole-1,2-dicarboxylate
The title compound, C22H17N3O4, was prepared through 1,3-dipolar cycloaddition: the dihedral angle between the benzimidazole and benzene rings is 80.93 (6)°. The crystal structure is stabilized by weak π–π interactions between the planar pyrrolobenzimidazole rings (r.m.s. deviation = 0.0293 Å) of neighbouring molecules, forming chains along the c axis. The perpendicular distance is 3.47 (2) Å and the centroid–centroid distances are in the range of 3.590 (3)–3.944 (3) Å
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