Search

This paper discusses the regularity of the GP-V’-rings in conjunction with idempotent reflexivity for the first time. We mainly discuss the weak and strong regularity of the GP-V’-rings using generalized weak ideals, weakly right ideals, and quasi-ideals. We show the following: (1) If R is an idempotent reflexive semi-abelian left GP-V’-ring whose every maximal essential left ideal is a generalized weak ideal, a weakly right ideal, or a quasi-ideal, then R is a reduced left weakly regular ring. (2) R is a strongly regular ring if and only if R is an idempotent reflexive semi-commutative left GP-V’-ring whose every maximal essential left ideal is a generalized weak ideal, a weakly right ideal, or a quasi-ideal. (3) If R is a semi-primitive idempotent reflexive ring whose every simple singular left R-module is flat, and every maximal left ideal is a generalized weak ideal, then, for any nonzero element a∈R, there exists a positive integer n such that an≠0, and RaR+lan=R.

Land use transition and its eco-environmental effects are important research topics. Its essence is the process that human activities exert interference to the ecological environment in the process of social and economic development, and the ecosystem resists interference and recovers and adapts to interference. The article starts from the transition of land use dominant morphology and takes ecological resilience as the breakthrough point. Based on four periods of land use data, this article studied the spatio-temporal evolution of land use and ecological resilience and the response of ecological resilience to land use transition in China from 1990 to 2020. The results showed as follows: (1) During the study period, the construction land in China continued to increase, and the forest land, grassland, and farmland showed a fluctuating trend. (2) The spatial distribution pattern of ecological resilience showed the characteristics of “high in the southeast and low in the northwest”. The mean value and total value of ecological resilience in the region decreased first and then increased, taking 2010 as the dividing line. The difference in ecological resilience increased first and then decreased. (3) Ecological land and construction land are the main types of land that affect the changes in ecological resilience. The higher the proportion of ecological lands such as forest land, grassland, and waters, the smaller the variable coefficient of ecological resilience. The higher the proportion of construction land, the greater the difference in ecosystem elasticity among different types of areas.

Urbanization and land use transformation are typical characteristics of China in recent decades. Studying the effects of urban land use transitions (ULUT) on the economic spatial spillovers of central cities (ESSCC) can provide a reference for China to optimize cities’ land space layout and promote their coordinated development. Based on the direct and indirect effects of ULUT in central cities on the production factors and economic growth in other cities, this paper reveals the mechanisms underlying the influence of ULUT on ESSCC. Then, we usethe expanded geographical distance-weighted spatial Durbin model with the panel data of 152 Chinese urban agglomeration cities from 2003 to 2016 to empirically test it. The results show that, since 2003, the rate of urban land expansions, the level of urban land intensive use (ULIU), the degree of land marketization, and the urban land prices in China have increased substantially; and the proportionate supplies of industrial land, commercial land, and residential land have decreased. Moreover, ULUT between cities have significant spatial autocorrelations. The current ULUT have positive but small effects on ESSCC. Among them, ULIU has the greatest promotion effects on ESSCC. The impacts of ULUT on ESSCC vary greatly among urban agglomerations. The ULUT in central cities indirectly enhance the ESSCC, which mainly depend on the positive effects of ULUT on enterprise investment, infrastructure investment, labor and technological efficiency and the spatial spread effects of these production factors. This is the main intermediate mechanism by which the ULUT in central cities enhance the ESSCC. Continuing to strengthen ULIU, promote the improvement of land marketization, and establish and improve the coordination mechanism for the economic development of urban agglomerations will help to strengthen the ESSCC in urban agglomerations. The results provide evidence for how the Chinese government can enhance the ESSCC and promote the coordinated development of cities through ULUT under new urbanization.