Single-Pixel Background Modeling Algorithm for Strong Sky Scenes Based on Local Region Spatial Bases.

In the dim-small target detection field, background suppression is a key technique for stably extracting the target. In order to effectively suppress the background to enhance the target, this paper presents a novel background modeling algorithm, which constructs base functions for each pixel based on the local region background and models the background of each pixel, named single pixel background modeling (SPB). In SPB, the low-rank blocks of the local backgrounds are first obtained to construct the background base functions of the center pixel. Then, the background of the center pixel is optimally estimated by the background bases. Experiments demonstrate that in the case of extremely low signal-to-noise ratio (SNR < 1.5 dB) and complex motion state of targets, SPB can stably and effectively separate the target from the strongly undulant sky background. The difference image obtained via SPB background modeling has the characters: the non-target residual could be white noise, and the target is significantly enhanced. Compared with the other typical five algorithms, SPB remarkably outperforms other algorithms to detect the target of a low signal-to-noise ratio.

The synergistic effect of surface and bulk O vacancies in a WO3 photoanode to advance carrier separation and light harvesting for photoelectrochemical water splitting.

It is critical to fabricate a photoanode with the virtues of high carrier separation efficiency and light harvesting to reduce the recombination of carriers and enhance the utilization of solar energy in photoelectrochemical (PEC) water splitting. In this work, WO3 nanoflake photoanodes with surface and bulk O vacancies (D-WO3-x) were fabricated via a hydrothermal method and H2WO4 etching to reveal the respective roles and collaborative effect of O vacancies in the surface and bulk. The surface O vacancies leave abundant active sites to reduce the redox barrier. Furthermore, the bulk O vacancies act as electron trap centers for heightening carrier separation efficiency. More importantly, the surface and bulk O vacancies in D-WO3-x reduce the band gap so that the resistance to electron jumping is reduced and light harvesting is increased. As expected, the photocurrent density of D-WO3-x is 0.98 mA cm-2 at 1.23 V vs. RHE, which is 5 times that of pristine WO3. Moreover, the carrier separation efficiencies in the surface and bulk are 2.38 and 2.26 times that of WO3. This work provides a promising method for the development of high-performance photoanodes via introducing surface and bulk O vacancies in semiconductors.