98 research outputs found
Data-driven approach for synchrotron X-ray Laue microdiffraction scan analysis
We propose a novel data-driven approach for analyzing synchrotron Laue X-ray
microdiffraction scans based on machine learning algorithms. The basic
architecture and major components of the method are formulated mathematically.
We demonstrate it through typical examples including polycrystalline BaTiO,
multiphase transforming alloys and finely twinned martensite. The computational
pipeline is implemented for beamline 12.3.2 at the Advanced Light Source,
Lawrence Berkeley National Lab. The conventional analytical pathway for X-ray
diffraction scans is based on a slow pattern by pattern crystal indexing
process. This work provides a new way for analyzing X-ray diffraction 2D
patterns, independent of the indexing process, and motivates further studies of
X-ray diffraction patterns from the machine learning prospective for the
development of suitable feature extraction, clustering and labeling algorithms.Comment: 29 pages, 25 figures under the second round of review by Acta
Crystallographica
Energy conversion from heat to electricity by highly reversible phase-transforming ferroelectrics
Searching for performant multiferroic materials attracts general research
interests in energy science as they have been increasingly exploited as the
conversion media among thermal, electric, magnetic and mechanical energies by
using their temperature-dependent ferroic properties. Here we report a material
development strategy that guides us to discover a reversible phase-transforming
ferroelectric material exhibiting enduring energy harvesting from small
temperature differences. The material satisfies the crystallographic
compatibility condition between polar and nonpolar phases, which shows only
2.5C thermal hysteresis and high figure of merit. It stably generates 15uA
electricity in consecutive thermodynamic cycles in absence of any bias fields.
We demonstrate our device to consistently generate 6uA/cm2 current density near
100C over 540 complete phase transformation cycles without any electric and
functional degradation. The energy conversion device can light up a LED
directly without attaching an external power source. This promising material
candidate brings the low-grade waste heat harvesting closer to a practical
realization, e.g. small temperature fluctuations around the water boiling point
can be considered as a clean energy source.Comment: 21 pages, 9 figures, 2 table
Hierarchical Few-Shot Object Detection: Problem, Benchmark and Method
Few-shot object detection (FSOD) is to detect objects with a few examples.
However, existing FSOD methods do not consider hierarchical fine-grained
category structures of objects that exist widely in real life. For example,
animals are taxonomically classified into orders, families, genera and species
etc. In this paper, we propose and solve a new problem called hierarchical
few-shot object detection (Hi-FSOD), which aims to detect objects with
hierarchical categories in the FSOD paradigm. To this end, on the one hand, we
build the first large-scale and high-quality Hi-FSOD benchmark dataset
HiFSOD-Bird, which contains 176,350 wild-bird images falling to 1,432
categories. All the categories are organized into a 4-level taxonomy,
consisting of 32 orders, 132 families, 572 genera and 1,432 species. On the
other hand, we propose the first Hi-FSOD method HiCLPL, where a hierarchical
contrastive learning approach is developed to constrain the feature space so
that the feature distribution of objects is consistent with the hierarchical
taxonomy and the model's generalization power is strengthened. Meanwhile, a
probabilistic loss is designed to enable the child nodes to correct the
classification errors of their parent nodes in the taxonomy. Extensive
experiments on the benchmark dataset HiFSOD-Bird show that our method HiCLPL
outperforms the existing FSOD methods.Comment: Accepted by ACM MM 202
Assessment Model of Ecoenvironmental Vulnerability Based on Improved Entropy Weight Method
Assessment of ecoenvironmental vulnerability plays an important role in the guidance of regional planning, the construction and protection of ecological environment, which requires comprehensive consideration on regional resources, environment, ecology, society and other factors. Based on the driving mechanism and evolution characteristics of ecoenvironmental vulnerability in cold and arid regions of China, a novel evaluation index system on ecoenvironmental vulnerability is proposed in this paper. For the disadvantages of conventional entropy weight method, an improved entropy weight assessment model on ecoenvironmental vulnerability is developed and applied to evaluate the ecoenvironmental vulnerability in western Jilin Province of China. The assessing results indicate that the model is suitable for ecoenvironmental vulnerability assessment, and it shows more reasonable evaluation criterion, more distinct insights and satisfactory results combined with the practical conditions. The model can provide a new method for regional ecoenvironmental vulnerability evaluation
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