88 research outputs found
Toward multi-target self-organizing pursuit in a partially observable Markov game
The multiple-target self-organizing pursuit (SOP) problem has wide
applications and has been considered a challenging self-organization game for
distributed systems, in which intelligent agents cooperatively pursue multiple
dynamic targets with partial observations. This work proposes a framework for
decentralized multi-agent systems to improve intelligent agents' search and
pursuit capabilities. We model a self-organizing system as a partially
observable Markov game (POMG) with the features of decentralization, partial
observation, and noncommunication. The proposed distributed algorithm: fuzzy
self-organizing cooperative coevolution (FSC2) is then leveraged to resolve the
three challenges in multi-target SOP: distributed self-organizing search (SOS),
distributed task allocation, and distributed single-target pursuit. FSC2
includes a coordinated multi-agent deep reinforcement learning method that
enables homogeneous agents to learn natural SOS patterns. Additionally, we
propose a fuzzy-based distributed task allocation method, which locally
decomposes multi-target SOP into several single-target pursuit problems. The
cooperative coevolution principle is employed to coordinate distributed
pursuers for each single-target pursuit problem. Therefore, the uncertainties
of inherent partial observation and distributed decision-making in the POMG can
be alleviated. The experimental results demonstrate that distributed
noncommunicating multi-agent coordination with partial observations in all
three subtasks are effective, and 2048 FSC2 agents can perform efficient
multi-target SOP with almost 100% capture rates
Unveiling microstructural damage for leakage current degradation in SiC Schottky diode after heavy ions irradiation under 200 V
Single-event burnout and single-event leakage current (SELC) in SiC power
devices induced by heavy ions severely limit their space application, and the
underlying mechanism is still unclear. One fundamental problem is lack of
high-resolution characterization of radiation damage in the irradiated SiC
power devices, which is a crucial indicator of the related mechanism. In this
letter, high-resolution transmission electron microscopy (TEM) was used to
characterize the radiation damage in the 1437.6 MeV 181Ta-irradiated SiC
junction barrier Schottky diode under 200 V. The amorphous radiation damage
with about 52 nm in diameter and 121 nm in length at the Schottky metal
(Ti)-semiconductor (SiC) interface was observed. More importantly, in the
damage site the atomic mixing of Ti, Si, and C was identified by electron
energy loss spectroscopy and high-angle annular dark-field scanning TEM. It
indicates that the melting of the Ti-SiC interface induced by localized Joule
heating is responsible for the amorphization and the formation of titanium
silicide, titanium carbide, or ternary phases. These modifications at nanoscale
in turn cause the localized degradation of the Schottky contact into Ohmic
contact, resulting in the permanent increase in leakage current. This
experimental study provides some valuable clues to thorough understanding of
the SELC mechanism in SiC diode.Comment: 4 pages,4 figure
Genome-wide Association Study (GWAS) of mesocotyl elongation based on re-sequencing approach in rice
Annotation of candidate genes anchored by associated SNPs. (XLSX 34 kb
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