13 research outputs found
Hyperspectral Image Classification Based on Mutually Guided Image Filtering
Hyperspectral remote sensing images (HSIs) have both spectral and spatial characteristics. The adept exploitation of these attributes is central to enhancing the classification accuracy of HSIs. In order to effectively utilize spatial and spectral features to classify HSIs, this paper proposes a method for the spatial feature extraction of HSIs based on a mutually guided image filter (muGIF) and combined with the band-distance-grouped principal component. Firstly, aiming at the problem that previously guided image filtering cannot effectively deal with the inconsistent information structure between the guided and target information, a method for extracting spatial features using muGIF is proposed. Then, aiming at the problem of the information loss caused by a single principal component as a guided image in the traditional GIF-based spatial–spectral classification, a spatial feature-extraction framework based on the band-distance-grouped principal component is proposed. The method groups the bands according to the band distance and extracts the principal components of each set of band subsets as the guide map of the current band subset to filter the HSIs. A deep convolutional neural network model and a generative adversarial network model for the filtered HSIs are constructed and then trained using samples for HSIs’ spatial–spectral classification. Experiments show that compared with the traditional methods and several popular spatial–spectral HSI classification methods based on a filter, the proposed methods based on muGIF can effectively extract the spatial–spectral features and improve the classification accuracy of HSIs
Pollution Status and Human Exposure of Decabromodiphenyl Ether (BDE-209) in China
Decabromodiphenyl
ether (BDE-209/decaBDE) is a high-production-volume
brominated flame retardant in China, where the decaBDE commercial
mixture is manufactured in Laizhou Bay, Shandong Province, even after
the prohibition of penta- and octaBDE mixtures. The demand for flame
retardants produced in China has been increasing in recent years as
China not only produces electronic devices but also has numerous electronic
waste (e-waste) recycling regions, which receive e-wastes from both
domestic and foreign sources. High concentrations of BDE-209 have
been observed in biotic and abiotic media in each of the different
areas, especially within the decaBDE manufacturers and e-waste recycling
areas. BDE-209 has been viewed as toxic and bioaccumulative because
it might debrominate to less brominated polybrominated diphenyl ethers
(PBDEs) (lower molecular weight and hydrophobicity), which are more
readily absorbed by organisms. The highest concentration of PBDEs
in dust within urban areas reached 40 236 ng g<sup>–1</sup> in the Pearl River Delta, and BDE-209 contributed the greatest proportion
to the total PBDEs (95.1%). Moreover, the maximum hazard quotient
was found for toddlers (0.703) for BDE-209, which was close to 1.
This suggests that exposure to BDE-209 might lead to increased potential
for adverse effects and organ harm (e.g., the lungs) through inhalation,
dust ingestion, and dermal absorption, especially for the group of
toddlers compared to others. In daily food and human tissues, the
amount of BDE-209 was also extensively detected. However, the toxicity
and adverse effect of BDE-209 to humans are still not clear; thus,
further studies are required to better assess the toxicological effects
and exposure scenarios, a more enhanced environmental policy for ecological
risks regarding BDE-209 and its debrominated byproducts in China