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Habitat quality is a key indicator for assessing the biodiversity-maintenance functions of ecosystem services. The issue of habitat quality changes in semi-arid and arid areas has been becoming serious, but there are few deep investigations of habitat quality in these regions, such as studies of the temporal and spatial changes of habitat quality and its driving forces. This study focuses on the agro-pastoral ecotone of northern Shaanxi with vulnerable biodiversity. By using the Fragstats software, the InVEST model, and the Geo-detector model, we analyzed land-use data collected from 1990, 2000, 2010, and 2020, and we explored the landscape pattern index, the spatial and temporal variation of habitat quality, and the influence of its drivers. GDP, population density, precipitation, temperature, land use, NDVI, elevation, and slope were detected by Geo-detector. The research results show that: (1) Arable land and grassland were the dominant land types from 1990 to 2020, and there was significant mutual circulation between arable land and grassland. Forest area increased by 24%. Many other land-use types were transformed into construction land, and construction land increased by 727% compared with the base period. (2) Landscape heterogeneity increased in the study region, shown by the fractured structure of the overall landscape and by the aggravated human disturbance of the landscape. (3) Average habitat quality underwent a trend of oscillation. Regarding spatial distribution, habitat quality was higher in the east than in the west. (4) The influencing factors of habitat quality monitored by Geo-detectors show that the driving force of land use on habitat quality was the strongest, followed by precipitation and vegetation coverage. Elevation, slope, GDP, and population density had the least influence on habitat quality. The bi-factor interaction enhanced habitat quality to different levels. This study is critical to the conservation of biodiversity and to ecological civilization construction in arid and semi-arid regions. [ABSTRACT FROM AUTHOR]

The brushless doubly fed induction machine (BDFIM) shows potential in replacing the wound rotor machines for certain industrial applications due to its higher reliability, a benefit of the absence of brush gears. This paper proposes an indirect stator-quantities control (ISC) strategy for the BDFIM. Theoretical derivation has been carried out to demonstrate the control principle for the proposed strategy. ISC provides the benefit of a simple structure, since it is implemented in two static reference frames and no rotating coordinate transformation is required. Furthermore, only two stator winding resistances are used, and therefore, the controller structure is less dependent on machine parameters. The experimental results of the prototype show the feasibility of the proposed strategy for the BDFIM. [ABSTRACT FROM AUTHOR]