33,348 research outputs found
Multi-level Feature Fusion-based CNN for Local Climate Zone Classification from Sentinel-2 Images: Benchmark Results on the So2Sat LCZ42 Dataset
As a unique classification scheme for urban forms and functions, the local
climate zone (LCZ) system provides essential general information for any
studies related to urban environments, especially on a large scale. Remote
sensing data-based classification approaches are the key to large-scale mapping
and monitoring of LCZs. The potential of deep learning-based approaches is not
yet fully explored, even though advanced convolutional neural networks (CNNs)
continue to push the frontiers for various computer vision tasks. One reason is
that published studies are based on different datasets, usually at a regional
scale, which makes it impossible to fairly and consistently compare the
potential of different CNNs for real-world scenarios. This study is based on
the big So2Sat LCZ42 benchmark dataset dedicated to LCZ classification. Using
this dataset, we studied a range of CNNs of varying sizes. In addition, we
proposed a CNN to classify LCZs from Sentinel-2 images, Sen2LCZ-Net. Using this
base network, we propose fusing multi-level features using the extended
Sen2LCZ-Net-MF. With this proposed simple network architecture and the highly
competitive benchmark dataset, we obtain results that are better than those
obtained by the state-of-the-art CNNs, while requiring less computation with
fewer layers and parameters. Large-scale LCZ classification examples of
completely unseen areas are presented, demonstrating the potential of our
proposed Sen2LCZ-Net-MF as well as the So2Sat LCZ42 dataset. We also
intensively investigated the influence of network depth and width and the
effectiveness of the design choices made for Sen2LCZ-Net-MF. Our work will
provide important baselines for future CNN-based algorithm developments for
both LCZ classification and other urban land cover land use classification
Magnitude Uncertainties Impact Seismic Rate Estimates, Forecasts and Predictability Experiments
The Collaboratory for the Study of Earthquake Predictability (CSEP) aims to
prospectively test time-dependent earthquake probability forecasts on their
consistency with observations. To compete, time-dependent seismicity models are
calibrated on earthquake catalog data. But catalogs contain much observational
uncertainty. We study the impact of magnitude uncertainties on rate estimates
in clustering models, on their forecasts and on their evaluation by CSEP's
consistency tests. First, we quantify magnitude uncertainties. We find that
magnitude uncertainty is more heavy-tailed than a Gaussian, such as a
double-sided exponential distribution, with scale parameter nu_c=0.1 - 0.3.
Second, we study the impact of such noise on the forecasts of a simple
clustering model which captures the main ingredients of popular short term
models. We prove that the deviations of noisy forecasts from an exact forecast
are power law distributed in the tail with exponent alpha=1/(a*nu_c), where a
is the exponent of the productivity law of aftershocks. We further prove that
the typical scale of the fluctuations remains sensitively dependent on the
specific catalog. Third, we study how noisy forecasts are evaluated in CSEP
consistency tests. Noisy forecasts are rejected more frequently than expected
for a given confidence limit. The Poisson assumption of the consistency tests
is inadequate for short-term forecast evaluations. To capture the
idiosyncrasies of each model together with any propagating uncertainties, the
forecasts need to specify the entire likelihood distribution of seismic rates.Comment: 35 pages, including 15 figures, agu styl
Review on Slip Transmission Criteria in Experiments and Crystal Plasticity Models
A comprehensive overview is given of the literature on slip transmission
criteria for grain boundaries in metals, with a focus on slip system and grain
boundary orientation. Much of this extensive literature has been informed by
experimental investigations. The use of geometric criteria in continuum crystal
plasticity models is discussed. The theoretical framework of Gurtin (2008, J.
Mech. Phys. Solids 56, p. 640) is reviewed for the single slip case. This
highlights the connections to slip transmission criteria from the literature
that are not discussed in the work itself. Different geometric criteria are
compared for the single slip case with regard to their prediction of slip
transmission. Perspectives on additional criteria, investigated in experiments
and used in computational simulations, are given.Comment: in Journal of Materials Science, 201
Effects of intra- and inter-laminar resin content on the mechanical properties of toughened composite materials
Composite materials having multiphase toughened matrix systems and laminate architectures characterized by resin-rich interlaminar layers (RIL) have been the subject of much recent attention. Such materials are likely to find applications in thick compressively loaded structures such as the keel area of commercial aircraft fuselages. The effects of resin content and its interlaminar and intralaminar distribution on mechanical properties were investigated with test and analysis of two carbon-epoxy systems. The RIL was found to reduce the in situ strengthening effect for matrix cracking in laminates. Mode 2 fracture toughness was found to increase with increasing RIL thickness over the range investigated, and Mode 1 interlaminar toughness was negligibly affected. Compressive failure strains were found to increase with increasing resin content for specimens having no damage, holes, and impact damage. Analytical tools for predicting matrix cracking of off-axis plies and damage tolerance in compression after impact (CAI) were successfully applied to materials with RIL
Alchemical and structural distribution based representation for improved QML
We introduce a representation of any atom in any chemical environment for the
generation of efficient quantum machine learning (QML) models of common
electronic ground-state properties. The representation is based on scaled
distribution functions explicitly accounting for elemental and structural
degrees of freedom. Resulting QML models afford very favorable learning curves
for properties of out-of-sample systems including organic molecules,
non-covalently bonded protein side-chains, (HO)-clusters, as well as
diverse crystals. The elemental components help to lower the learning curves,
and, through interpolation across the periodic table, even enable "alchemical
extrapolation" to covalent bonding between elements not part of training, as
evinced for single, double, and triple bonds among main-group elements
Alchemical and structural distribution based representation for improved QML
We introduce a representation of any atom in any chemical environment for the
generation of efficient quantum machine learning (QML) models of common
electronic ground-state properties. The representation is based on scaled
distribution functions explicitly accounting for elemental and structural
degrees of freedom. Resulting QML models afford very favorable learning curves
for properties of out-of-sample systems including organic molecules,
non-covalently bonded protein side-chains, (HO)-clusters, as well as
diverse crystals. The elemental components help to lower the learning curves,
and, through interpolation across the periodic table, even enable "alchemical
extrapolation" to covalent bonding between elements not part of training, as
evinced for single, double, and triple bonds among main-group elements
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