The accurate mapping of urban impervious surfaces from remote sensing images is crucial for understanding urban land-cover change and addressing impervious-surface-change-related environment issues. To date, the authors of most studies have built indices to map impervious surfaces based on shortwave infrared (SWIR) or thermal infrared (TIR) bands from middle–low-spatial-resolution remote sensing images. However, this limits the use of high-spatial-resolution remote sensing data (e.g., GaoFen-2, Quickbird, and IKONOS). In addition, the separation of bare soil and impervious surfaces has not been effectively solved. In this article, on the basis of the spectra analysis of impervious surface and non-impervious surface (vegetation, water, soil and non-photosynthetic vegetation (NPV)) data acquired from world-recognized spectral libraries and Sentinel-2 MSI images in different regions and seasons, a novel spectral index named the Normalized Impervious Surface Index (NISI) was proposed for extracting impervious area information by using blue, green, red and near-infrared (NIR) bands. We performed comprehensive assessments for the NISI, and the results demonstrated that the NISI provided the best studied performance in separating the soil and impervious surfaces from Sentinel-2 MSI images. Furthermore, regarding impervious surfaces mapping accuracy, the NISI had an overall accuracy (OA) of 89.28% (±0.258), a producer’s accuracy (PA) of 89.76% (±1.754), and a user’s accuracy (UA) of 90.68% (±1.309), which were higher than those of machine learning algorithms, thus supporting the NISI as an effective measurement for urban impervious surfaces mapping and analysis. The results indicate the NISI has a high robustness and a good applicability.

Land surface temperature (LST) is a critical parameter for the dynamic simulation of land surface processes and for analyzing variations on regional or global scales. Obtaining LST with high spatiotemporal resolution is a subject of intensive and ongoing research. This study proposes a pixel-wise temporal alignment iterative linear regression model for downscaling based on MODIS LST products. This approach allows us to address the problem of high temporal resolution but low spatial resolution of the ERA5 reanalysis LST product while remaining immune to the pixel loss caused by clouds. The hourly ERA5 LST of the study area for 2012–2021 was downscaled to a 1000 m resolution, and its accuracy was verified by comparison with measured data from meteorological stations. The downscaled LST offers intricate details and is faithful to the LST characteristics of distinct land-cover categories. In comparison with other downscaling techniques, the proposed technique is more stable and preserves the spatial distribution of the ERA5 LST with minimal missing pixels. The pixel-wise average R² and mean absolute error for the MODIS view times are 0.87 and 2.7 K, respectively, for cloud-free conditions on a 1000 m scale. The accuracy verification using data from meteorological stations indicates that the overall error is lower during cloudless periods rather than during overcast periods, during the night rather than during the day, and at MODIS view times rather than at non-view times. The maximum and minimum mean errors are 0.13 K for cloud-free periods and −0.98 K for cloudy periods, indicating a slight underestimation and overestimation, respectively. Conversely, the maximum and minimum mean absolute errors are 2.01 K for the daytime and 0.85 K for the nighttime. Therefore, the model ensures higher accuracy during cloudy periods with only the clear-sky LST used as input data, making it suitable for long-term, all-weather ERA5 LST downscaling.

Magnetostrictive characteristics of Galfenol were researched and a new type of magnetostrictive pressure sensor based on the Galfenol was proposed to implement the accurate perception of tactile sensation for robots. The sensor converts a pressure signal into a voltage signal based on magnetostrictive inverse effect to implement the accurate measurement of the pressure. The magnetostrictive pressure sensor was designed and fabricated, and the magnetic field of pressure sensor was optimized by a magnetic circuit of double permanent magnets. Then, the sensor was analyzed theoretically and investigated experimentally, and the influences of bias condition, external pressure and other factors on the peak value of output voltage were discussed. The results show that when bias magnetic field is 4.8 kA/m and applied pressure is 2.5 Hz and 6 N, the peak value of output voltage reaches 16 mV and the peak value of output voltage has better linear relation with the pressure. The developed sensor is characteristics by simple structure, good linearity, and a quick response speed. It meets the requirements of tactile sensation of robots and is suitable for the pressure measurement in other fields .

In order to explore the microstructure and properties of NiCoCrAlY coating under different laser scanning speed, the NiCoCrAlY coating was melted and deposited on the IN718 surface by laser cladding technology. The forming condition, microstructure, hardness, friction and wear properties of the coating were analyzed, and the dynamic relationship among scanning speed, microstructure and coating properties was established. The results show that the NiCoCrAlY coating has a good shape at different scanning speeds, and the solidification structure is columnar dendrite and equiaxed dendrite which is perpendicular to the solid-liquid interface and grows directionally and epitaxially. With the increase of scanning speed, the coating temperature gradient increases, the solidification rate increases, the grain structure is refined, and the coating microhardness increases slightly. At the same time, with the increase of the scanning speed, the average friction coefficient and wear rate of the coating first decrease and then increase. The results show that the wear resistance of the coating obtained at 12 mm/s scanning speed is better.

针对基因测序、半导体检测、工业显微镜及生命医疗等领域对显微物镜日益增长的技术需求，成像谱段向着宽谱段深紫外（DUV）方向发展，目前非浸液式显微物镜存在数值孔径（NA）低、视场小、宽谱段内色差严重等问题。基于此，提出一款折反射式物镜。所提折反射式物镜具有宽谱段、高数值孔径、消色差等优点，根据折反射式结构的消色差光学特性，镜片只采用一种材料就可以校正色差。系统由12片镜片组成，数值孔径为0.91，成像谱段为深紫外到可见光（275~600 nm），最大视场为0.3 mm，系统全视场全谱段波像差小于0.033λ，消除了二级光谱，成像质量满足使用要求。

A narrow-linewidth tunable laser based on a unique dual-lens external-cavity structure was reported, in which a thermally-tuned 50 GHz etalon was utilized to provide standard ITU-grid wavelengths and a PZT-actuated tunable Fabry-Pérot filter to select wavelength. In experiment, the laser wavelength could be tuned from 1 525 to 1 580 nm, covering the whole C band. And it measured a linewidth of 37.5 kHz, an output power ＞50 mW at the 400 mA pump current, a SMSR > 50 dB and a tuning speed ＜3 ms. The performance is superior to the requirements of coherent communication applications and the reported planar waveguide-based counterparts. Moreover, the dual-lens structure bears other merits such as high positioning tolerance and potential for ultra-narrow linewidth. It may have a wide application after miniaturization and standard packaging.