Subjects: Geosciences >> Geography submitted time 2024-06-12 Cooperative journals: 《干旱区研究》
Abstract： Farmland use intensity is an important factor to improve food production, alleviate the conflict between humans and land, and achieve sustainable agricultural development. Based on the farmland data obtained from high spatial resolution remote sensing images, this paper explores the farmland use intensity and its driving mechanism in the Yarlung Zangbo-Lhasa-Nyangqu River (YLN) region in 2000 and 2020 through a comprehensive evaluation index model. The results show that: (1) the degree of farmland use intensity in the YLN region has increased in the past 20 years, but the overall level is low. The farmland use intensity in 2020 was 38.2% higher than in 2000, which is mainly attributable to the increase in agricultural input, technological input, and the exploitation and utilization level. (2) There is a large difference in the change in farmland use intensity among different districts and counties; the high intensity areas migrated from east to west and increased in scope. The difference in farmland use intensity between east and west regions narrowed, and the number of low intensity districts and counties decreased. (3) The irrigation index, proportion of farmland area, and farmland quality have the most significant independent effects on the degree of farmland use intensity in the YLN, whereas socioeconomic factors, agricultural science and technology factors, and policy and environment factors interact with farmland resource endowment to increase the degree of impact on the farmland use intensity. Based on the above results, the following policy recommendations are proposed: the continuous promotion of agricultural science and technology innovation in the YLN region with a focus on regional differences, to realize sustainable development in high intensity areas and total factor inputs in low intensity areas, and facilitate the synergistic effects of agricultural policy and economy to coordinate and promote enhanced farmland use intensity in the YLN region.
Subjects: Geosciences >> Space Physics submitted time 2016-04-22
Abstract： Schmidt and Angel lobster-eye X-ray imaging system can realize total reflection focusing and imaging by simulating lobster-eye microchannel structure. Compared with traditional way of X-ray imaging, it is provided with large field of detection view, high resolution and energy acquisition ability. This paper studies on two lobster-eye basic structures. Based on the principle of grazing incidence, we analyzed Angel and Schmidt structure of light entering focal plane and space resolution. We use tracepro simulation software to model and verify the several focusing and imaging property parameters of these two lobster-eye structures, such as receiving/transmitting light, maximum/cross arm, maximum/background, cross arm/background. The theoretical analysis and simulation results show, when the focal length is longer and channel length-width ratio is about 50. Due to multiple reflection, focusing and imaging signal-to-noise ratio of some main parameters of Schmidt is higher than Angel model, and the spatial resolution is lower. When the focal length is shorter and channel length-width ratio is about 10. Due to simple reflection, focusing and imaging signal-to-noise ratio of some main parameters of Schmidt is lower than Angel model, and the spatial resolution is almost the same.
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