8,104 research outputs found
Higher Education Research Institutes in China
書名: Higher Education Research: Challenges and Prospects. Report of RIHE’s 50th Anniversary International Symposium, 202
Fractal analysis of the effect of particle aggregation distribution on thermal conductivity of nanofluids
This project was supported by the National Natural Science Foundation of China (No. 41572116), the Fundamental Research Funds for the Central Universities, China University of Geosciences, Wuhan) (No. CUG160602).Peer reviewedPostprin
Photoconductivity of Single-crystalline Selenium Nanotubes
Photoconductivity of single-crystalline selenium nanotubes (SCSNT) under a
range of illumination intensities of a 633nm laser is carried out with a novel
two terminal device arrangement at room temperature. It's found that SCSNT
forms Schottky barriers with the W and Au contacts, and the barrier height is a
function of the light intensities. In low illumination regime below 1.46x10E-4
muWmum-2, the Au-Se-W hybrid structure exhibits sharp switch on/off behavior,
and the turn-on voltages decrease with increasing illuminating intensities. In
the high illumination regime above 7x10E-4 muWmum-2, the device exhibits ohmic
conductance with a photoconductivity as high as 0.59Ohmcm-1, significantly
higher that reported values for carbon and GaN nanotubes. This finding suggests
that SCSNT is potentially a good photo-sensor material as well we a very
effective solar cell material.Comment: 12pages including 5 figures, submitted to Nanotechnolog
Neural Proximal/Trust Region Policy Optimization Attains Globally Optimal Policy
Proximal policy optimization and trust region policy optimization (PPO and
TRPO) with actor and critic parametrized by neural networks achieve significant
empirical success in deep reinforcement learning. However, due to nonconvexity,
the global convergence of PPO and TRPO remains less understood, which separates
theory from practice. In this paper, we prove that a variant of PPO and TRPO
equipped with overparametrized neural networks converges to the globally
optimal policy at a sublinear rate. The key to our analysis is the global
convergence of infinite-dimensional mirror descent under a notion of one-point
monotonicity, where the gradient and iterate are instantiated by neural
networks. In particular, the desirable representation power and optimization
geometry induced by the overparametrization of such neural networks allow them
to accurately approximate the infinite-dimensional gradient and iterate.Comment: A short versio
Left-handedness without absorption in the four-level Y-type atomic medium
In this paper,three external fields interacting with the four-level Y-type
atomic system described by the density-matrix approach is investigated .The
results show that the left-handedness with zero absorption are achieved.And the
zero absorption property displays the possibility of manipulation with varying
the phase and the intensity of the coupling field. The zero absorption property
may be used to amplify the evanescent waves that have been lost in the imaging
by traditional lenses.Our scheme proposes an approach to obtain negative
refractive medium with zero absorption and the possibility to enhance the
imaging resolution in realizing "superlenses".Comment: 8 pages, 3 figures. arXiv admin note: substantial text overlap with
arXiv:2403.00042; text overlap with arXiv:2403.0084
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