4,403 research outputs found
The Role of Chaos in One-Dimensional Heat Conductivity
We investigate the heat conduction in a quasi 1-D gas model with various
degree of chaos. Our calculations indicate that the heat conductivity
is independent of system size when the chaos of the channel is strong enough.
The different diffusion behaviors for the cases of chaotic and non-chaotic
channels are also studied. The numerical results of divergent exponent
of heat conduction and diffusion exponent are in consistent with the
formula . We explore the temperature profiles numerically and
analytically, which show that the temperature jump is primarily attributed to
superdiffusion for both non-chaotic and chaotic cases, and for the latter case
of superdiffusion the finite-size affects the value of remarkably.Comment: 6 pages, 7 figure
Convolutional Visual Prompt for Robust Visual Perception
Vision models are often vulnerable to out-of-distribution (OOD) samples
without adapting. While visual prompts offer a lightweight method of
input-space adaptation for large-scale vision models, they rely on a
high-dimensional additive vector and labeled data. This leads to overfitting
when adapting models in a self-supervised test-time setting without labels. We
introduce convolutional visual prompts (CVP) for label-free test-time
adaptation for robust visual perception. The structured nature of CVP demands
fewer trainable parameters, less than 1\% compared to standard visual prompts,
combating overfitting. Extensive experiments and analysis on a wide variety of
OOD visual perception tasks show that our approach is effective, improving
robustness by up to 5.87% over several large-scale models
Modeling Distances in Large-Scale Networks by Matrix Factorization
In this paper, we propose a model for representing and predicting distances in large-scale networks by matrix factorization. The model is useful for network distance sensitive applications, such as content distribution networks, topology-aware overlays, and server selections. Our approach overcomes several limitations of previous coordinates-based mechanisms, which cannot model sub-optimal routing or asymmetric routing policies. We describe two algorithms -- singular value decomposition (SVD) and nonnegative matrix factorization (NMF) -- for representing a matrix of network distances as the product of two smaller matrices. With such a representation, we build a scalable system -- Internet Distance Estimation Service (IDES) -- that predicts large numbers of network distances from limited numbers of measurements. Extensive simulations on real-world data sets show that IDES leads to more accurate, efficient and robust predictions of latencies in large-scale networks than previous approaches
A statistical classification of the unassociated gamma-ray sources in the second Fermi Large Area Telescope Catalog
With assistance of the identified/associated sources in the second Fermi
Large Area Telescope (LAT) catalog, we analyze and resolve the spatial
distribution and the distributions of the gamma-ray spectral and variability
indices of the remaining 575 unassociated Fermi LAT sources. Consequently, it
is suggested that the unassociated sources could statistically consist of
Galactic supernova remnants/pulsar wind nebulae, BL Lacertae objects, flat
spectrum radio quasars, and other types of active galaxies with fractions of
25%, 29%, 41%, and 5%, respectively.Comment: 8 pages, 7 figures, accepted for publication in Research in Astronomy
and Astrophysics (RAA
Analysis the Present Situation of Chinese Electronic Government Based on Fundamental Data
Electronic government can improve service delivery, transparency, and encourage citizens to participate government affairs which could promote government efficiency. This paper gives a full and statistics analysis on the data which collect from questionnaires by e-mail survey. Finally, the purpose of this paper is to offer some practical and effective advices for the future successful e-government development in China
Efficient interpolation of molecular properties across chemical compound space with low-dimensional descriptors
We demonstrate accurate data-starved models of molecular properties for
interpolation in chemical compound spaces with low-dimensional descriptors.
Our starting point is based on three-dimensional, universal, physical
descriptors derived from the properties of the distributions of the eigenvalues
of Coulomb matrices. To account for the shape and composition of molecules, we
combine these descriptors with six-dimensional features informed by the
Gershgorin circle theorem. We use the nine-dimensional descriptors thus
obtained for Gaussian process regression based on kernels with variable
functional form, leading to extremely efficient, low-dimensional interpolation
models. The resulting models trained with 100 molecules are able to predict the
product of entropy and temperature () and zero point vibrational
energy (ZPVE) with the absolute error under 1 kcal mol for \% and
under 1.3 kcal mol for \% of molecules in the test data. The test
data comprises 20,000 molecules with complexity varying from three atoms to 29
atoms and the ranges of and ZPVE covering 36 kcal mol and
161 kcal mol, respectively. We also illustrate that the descriptors
based on the Gershgorin circle theorem yield more accurate models of molecular
entropy than those based on graph neural networks that explicitly account for
the atomic connectivity of molecules.Comment: 29 pages, 12 figures, submitted to Machine Learning: Science and
Technology November 22nd, 202
Medium effects on the selection of sequences folding into stable proteins in a simple model
We study the medium effects on the selection of sequences in protein folding
by taking account of the surface potential in HP-model. Our analysis on the
proportion of H and P monomers in the sequences gives a direct interpretation
that the lowly designable structures possess small average gap. The numerical
calculation by means of our model exhibits that the surface potential enhances
the average gap of highly designable structures. It also shows that a most
stable structure may be no longer the most stable one if the medium parameters
changed.Comment: 4 pages, 4 figure
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