Double-gate fully-depleted (DGFD) SOI circuits are regarded as the next generation VLSI circuits. This paper investigates the impact of scaling on the demand and challenges of DGFD SOI circuit design for low power and high performance. We study how the added back-gate capacitance affects the circuit power and performance; how to trade off the enhanced short-channel effect immunity with the added back-channel leakage; and how the coupling between the front-and back-gates affects circuit reliability. Our analyses over different technology generations using MEDICI device simulator show that DGFD SOI circuits have significant advantages in driving high output load. DGFD SOI circuits also show excellent ability in controlling leakage current. However, for low output load, no gain is obtained for DGFD SOI circuits. Also, it is necessary to optimize the back-gate oxide thickness for best leakage control. Moreover, threshold variation may cause reliability problem for thin back-gate oxide DGFD SOI circuits operated at low power supply voltage.

Revealing the spatial–temporal pattern and convergence characteristics of urban land use efficiency has important guiding significance for adjusting and optimizing the regional urban land use structure. Taking the provincial units in China as the research object, the urban land use efficiency evaluation system considering the unexpected output was constructed, and the slack-based measure (SBA) model was used to quantitatively measure the provincial urban land use efficiency from 2000 to 2020. The exploratory spatial data analysis (ESDA) model and spatial convergence index were combined to reveal the spatial–temporal pattern and convergence characteristics of provincial urban land use efficiency. The results showed that the provincial urban land use efficiency has been continuously improving, with regional differences as shown in eastern region > northeast region > central region > western region. Moran’s I of provincial urban land use efficiency was greater than 0, there was a positive spatial correlation, and the clustering feature became increasingly significant. The spatial form of LISA was characterized by “small agglomeration and large dispersion”; the H(High)-H(High) type was clustered in the Yangtze River Delta and Beijing–Tianjin–Hebei, while the L(Low)-L(Low) type was clustered in Xizang, Xinjiang and Qinghai. There was a σ convergence in provincial urban land use efficiency, and there was significant absolute β convergence and conditional β convergence of provincial urban land use efficiency. The results showed that the differences in provincial urban land use efficiency were shrinking, showing a “catch-up effect”, and converging to their respective stable states over time. Based on the analysis of the spatial–temporal pattern and convergence characteristics of provincial urban land use efficiency in China, we could provide a direction for the optimization of the urban land use structure and efficiency improvement in China, in order to narrow the differences in urban land use efficiency in China’s four major regions.

Rural settlement is the core content of rural geography research. Exploring the spatial distribution characteristics and influencing factors of rural settlements can provide reference for the optimization of rural settlements. This paper selected Nanjing as a typical case, based on remote sensing image, using R statistics, kernel density analysis, hot spot detection analysis and semi variogram function; the paper analyzed the spatial, scale and morphological distribution characteristics of rural settlements; and preliminarily analyzed the influencing factors of rural settlements distribution in the metropolitan fringe area. The results showed that: (1) The spatial distribution of rural settlements generally presented a “multi-core” center, and a spatial distribution trend of stepwise decline from the core to the periphery, showing a typical “core-edge” structure. (2) There was a significant spatial difference in the scale distribution of rural settlements, which was characterized by a gradual decrease in the scale of rural settlements with the increase in the distance from the central urban area. (3) The morphological distribution of rural settlements showed spatial differentiation, and the morphological types of settlements mainly included strip, arcbelt, cluster and scatter. (4) The distribution of rural settlements was affected by such factors as terrain, river system, traffic, economic and social development, cultural and policy. The distribution of rural settlements had the location orientation of “low altitude, water affinity and road affinity”. The increase in agricultural population, rural economic development, cultural and policy factors played an important role in the distribution of rural settlements in the metropolitan fringe area.

Rural transformation development is an important part of rural revitalization, and the study of spatial–temporal differentiation characteristics and the driving mechanism of rural transformation development can provide a decision-making reference for formulating rural revitalization programs according to local conditions. Taking the Yangtze River Economic Belt as the research case, we constructed an evaluation system of rural transformation development in the dimension of “population, land and industry”, and the entropy TOPSIS method, spatial autocorrelation model and geographic detector model were used to reveal spatial-temporal differentiation and the driving mechanism of rural transformation development in the Yangtze River Economic Belt from 1978 to 2018. The results showed that (1) rural transformation development has been significantly unbalanced in the Yangtze River Economic Belt, and rural transformation development showed a weak distribution. Moreover, in terms of dimensions, the land use transformation level > population development transformation level > industrial development transformation level. (2) On the global, rural transformation development presented a spatial distribution trend of club convergence. On the local, the H(High)–H(High) type was mainly distributed in Shanghai City and the southern part of Jiangsu Province, and it evolved to Hangzhou-Shaoxing-Ningbo and Wanjiang City Belt; the L(Low)–L(Low) type was mainly concentrated in the western part of Sichuan Province and in the southwest of Yunnan Province. (3) Natural conditions, economic social development, traffic accessibility, policies and systems were the leading factors affecting rural transformation development in the Yangtze River Economic Belt. The influences of economic social development and traffic accessibility on rural transformation development were increasing, and policy factors had an important guiding effect on rural transformation development, and the influence of natural conditions on rural transformation development has weakened. This study can provide a practical reference for rural transformation and rural revitalization in the Yangtze River Economic Belt.

Double-gate fully depleted (DGFD) SOI circuits are regarded as the next generation VLSI circuits. This paper investigates the impact of scaling on the demand and challenges of DGFD SOI circuit design for low power and high performance. We study how the added back-gate capacitance affects circuit power and performance; how to tradeoff the enhanced short-channel effect immunity with the added back-channel leakage; and how the coupling between the front-and back-gates affects circuit reliability. Our analyses over different technology generations using MEDICI device simulator show that DGFD SOI circuits have significant advantages in driving high output load. DGFD SOI circuits also show excellent ability in controlling leakage current. However, for low output load, no gain is obtained for DGFD SOI circuits. Also, it is necessary to optimize the back-gate oxide thickness for best leakage control. Moreover, threshold variation may cause reliability problem for thin back-gate oxide DGFD SOI circuits operated at low supply voltage.