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High-resolution mapping and monitoring of national land use/cover changes contribute significantly to the knowledge of the interaction between human activities and environmental changes. China's Land Use/cover Dataset (CLUD) for 2020 and its dynamic changes in 2015-2020 were developed to extend the CLUD to over 30 years (i.e., the 1980s to 2020 at 5-year intervals) by integrating remote sensing big data and knowledge-based human-computer interaction interpretation methods. This integrating method for CLUD 2020 improved the efficiency of national land use/cover mapping and the accuracy of land use pattern change detection compared to earlier CLUD products, with an overall accuracy of 95%. The intensity of land use change decreased across China in 2015-2020 compared to 2010-2015, although both characteristics of its spatial changes were similar. The cropland area continued to shrink at national scale in 2015-2020, with two regional hotspots including the widespread conversions from dry land into paddy land in Northeast China and the coex-

The Qinghai–Tibet Plateau has seen decades of changes in land use/cover as a result of urbanization and regional planning policy. Research on the efficiency of social development aids in the pursuit of social and environmental sustainability. Based on CLUD and socioeconomic statistical data, this study systematically analyses the spatiotemporal evolution characteristics of urban land use in the Qinghai–Tibet Plateau and evaluates its social development efficiency from three perspectives—the holistic, the municipal, and urban hierarchy—by using indicators such as the Moran index, land use efficiency, and urban expansion speed and proportion. Results show that the urbanization rate climbed from 21.26% to 54.95%, and the area of urban lands increased from 201.93 km2 to 796.59 km2 from 1990 to 2020, with urban lands expanding from the Lanzhou–Xining City Area to the central and south of the Qinghai–Tibet Plateau. The holistic urban land use efficiency grew from 1.14 to 1.53, while the UPD decreased slightly from 1.44 to 1.31, and the UED increased steadily from 1.40 to 12.97 per decade. Moreover, we should pay attention to the rational allocation of land in human, social and ecosystem terms to comprehensively improve the quality of urbanization across the plateau.

Thermoelectric generators(TEG) is considered as a promising technology for utilizing low-grade thermal energy, while the cooling system plays a key role in TEG. A two-dimensional numerical model of jet impinging jet cooling is developed based on the commercial code FLUENT. The influences of several factors on thermoelectric conversion efficiency are observed. The factors include the air inlet velocity, the TE legs height, and the fins. The results show that the air inlet velocity is one of the most important factors for the cooling performance, the convection heat transfer efficiency and conversion efficiency significantly increases with the improvement of the air velocity. Higher TE legs height can influence the TEG performance effectively, 5~7mm legs height is recommended in this study. And fins can effectively increase the TEG efficiency, the thermoelectric conversion efficiency with 1mm×1mm fins is 6.73% which was 2.4 times higher than without fins.