Monitoring Spatiotemporal Distribution of the GDP of Major Cities in China during the COVID-19 Pandemic.

Monitoring the fine spatiotemporal distribution of urban GDP is a critical research topic for assessing the impact of the COVID-19 outbreak on economic and social growth. Based on nighttime light (NTL) images and urban land use data, this study constructs a GDP machine learning and linear estimation model. Based on the linear model with better effect, the monthly GDP of 34 cities in China is estimated and the GDP spatialization is realized, and finally the GDP spatiotemporal correction is processed.

Estimation and Analysis of PM Concentrations with NPP-VIIRS Nighttime Light Images: A Case Study in the Chang-Zhu-Tan Urban Agglomeration of China.

Rapid economic and social development has caused serious atmospheric environmental problems. The temporal and spatial distribution characteristics of PM concentrations have become an important research topic for sustainable social development monitoring. Based on NPP-VIIRS nighttime light images, meteorological data, and SRTM DEM data, this article builds a PM concentration estimation model for the Chang-Zhu-Tan urban agglomeration.

Nitrogen migration in products during the microwave-assisted hydrothermal carbonization of spirulina platensis.

Nitrogen has a vital influence on the properties of the microwave-assisted hydrothermal carbonization (MHTC) products of Spirulina platensis (SP). The effects of hydrothermal temperature (140-220 °C) and time (1-4 h) on the product distribution and nitrogen migration of SP in MHTC were studied. Increasing temperature led to an increase in the carbon content, and a decrease in the nitrogen content in hydrochar.

Lightweight Deep Neural Network Method for Water Body Extraction from High-Resolution Remote Sensing Images with Multisensors.

Rapid and accurate extraction of water bodies from high-spatial-resolution remote sensing images is of great value for water resource management, water quality monitoring and natural disaster emergency response. For traditional water body extraction methods, it is difficult to select image texture and features, the shadows of buildings and other ground objects are in the same spectrum as water bodies, the existing deep convolutional neural network is difficult to train, the consumption of computing resources is large, and the methods cannot meet real-time requirements. In this paper, a water body extraction method based on lightweight MobileNetV2 is proposed and applied to multisensor high-resolution remote sensing images, such as GF-2, WorldView-2 and UAV orthoimages.

Employing low-temperature barriers to achieve strain-relaxed and high-performance GaN-based LEDs.

The epitaxial structure design of low-temperature barriers has been adopted to promote strain relaxation in multiple quantum well (MQWs) and achieve high-efficient GaN-based light-emitting diodes (LEDs). With these barriers, the relaxation value of wells increases from 0 to 4.59%.

GaN-based light-emitting diodes on various substrates: a critical review.

GaN and related III-nitrides have attracted considerable attention as promising materials for application in optoelectronic devices, in particular, light-emitting diodes (LEDs). At present, sapphire is still the most popular commercial substrate for epitaxial growth of GaN-based LEDs. However, due to its relatively large lattice mismatch with GaN and low thermal conductivity, sapphire is not the most ideal substrate for GaN-based LEDs.

Microstructures and growth mechanisms of GaN films epitaxially grown on AlN/Si hetero-structures by pulsed laser deposition at different temperatures.

2 inch-diameter GaN films with homogeneous thickness distribution have been grown on AlN/Si(111) hetero-structures by pulsed laser deposition (PLD) with laser rastering technique. The surface morphology, crystalline quality, and interfacial property of as-grown GaN films are characterized in detail. By optimizing the laser rastering program, the ~300 nm-thick GaN films grown at 750 °C show a root-mean-square (RMS) thickness inhomogeneity of 3.

Highly-efficient GaN-based light-emitting diode wafers on La 0.3 Sr 1.7 AlTaO6 substrates.

Highly-efficient GaN-based light-emitting diode (LED) wafers have been grown on La 0.3 Sr 1.7 AlTaO6 (LSAT) substrates by radio-frequency molecular beam epitaxy (RF-MBE) with optimized growth conditions.