998 research outputs found
PseudoCal: A Source-Free Approach to Unsupervised Uncertainty Calibration in Domain Adaptation
Unsupervised domain adaptation (UDA) has witnessed remarkable advancements in
improving the accuracy of models for unlabeled target domains. However, the
calibration of predictive uncertainty in the target domain, a crucial aspect of
the safe deployment of UDA models, has received limited attention. The
conventional in-domain calibration method, \textit{temperature scaling}
(TempScal), encounters challenges due to domain distribution shifts and the
absence of labeled target domain data. Recent approaches have employed
importance-weighting techniques to estimate the target-optimal temperature
based on re-weighted labeled source data. Nonetheless, these methods require
source data and suffer from unreliable density estimates under severe domain
shifts, rendering them unsuitable for source-free UDA settings. To overcome
these limitations, we propose PseudoCal, a source-free calibration method that
exclusively relies on unlabeled target data. Unlike previous approaches that
treat UDA calibration as a \textit{covariate shift} problem, we consider it as
an unsupervised calibration problem specific to the target domain. Motivated by
the factorization of the negative log-likelihood (NLL) objective in TempScal,
we generate a labeled pseudo-target set that captures the structure of the real
target. By doing so, we transform the unsupervised calibration problem into a
supervised one, enabling us to effectively address it using widely-used
in-domain methods like TempScal. Finally, we thoroughly evaluate the
calibration performance of PseudoCal by conducting extensive experiments on 10
UDA methods, considering both traditional UDA settings and recent source-free
UDA scenarios. The experimental results consistently demonstrate the superior
performance of PseudoCal, exhibiting significantly reduced calibration error
compared to existing calibration methods
Microalbuminuria in relation to the metabolic syndrome and its components in a Chinese population
Diverse anisotropy of phonon transport in two-dimensional IV-VI compounds: A comparative study
New classes two-dimensional (2D) materials beyond graphene, including layered
and non-layered, and their heterostructures, are currently attracting
increasing interest due to their promising applications in nanoelectronics,
optoelectronics and clean energy, where thermal transport property is one of
the fundamental physical parameters. In this paper, we systematically
investigated the phonon transport properties of 2D orthorhombic group IV-VI
compounds of , , and by solving the Boltzmann transport
equation (BTE) based on first-principles calculations. Despite the similar
puckered (hinge-like) structure along the armchair direction as phosphorene,
the four monolayer compounds possess diverse anisotropic properties in many
aspects, such as phonon group velocity, Young's modulus and lattice thermal
conductivity (), etc. Especially, the along the zigzag and
armchair directions of monolayer shows the strongest anisotropy while
monolayer and shows an almost isotropy in phonon transport. The
origin of the diverse anisotropy is fully studied and the underlying mechanism
is discussed in detail. With limited size, the could be effectively
lowered, and the anisotropy could be effectively modulated by nanostructuring,
which would extend the applications in nanoscale thermoelectrics and thermal
management. Our study offers fundamental understanding of the anisotropic
phonon transport properties of 2D materials, and would be of significance for
further study, modulation and aplications in emerging technologies.Comment: 14 pages, 8 figures, 2 table
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