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A mathematical model of a drillstring-riser system is developed to analyze the system dynamics when drilling in deep water. For the proposed model, a riser and a drillstring are combined as a pipe-in-pipe structure, along which the interactions between the riser and the drillstring are introduced by a series of spring-friction units. Numerical simulations of the developed mathematical model are carried out by Abaqus in which the finite element method is adopted. Comparing with the riser deflection calculated by previously published models which exclude the influences of the drillstring-riser interactions, the maximal riser deflection obtained by using the proposed drillstring-riser system is relatively small. Namely, the drillstring-riser interactions restrict the riser deflection. This finding indicates that, in a given safety margin of the riser deflection, the drillstring-riser system has stronger capacity of anti-deflection. Additionally, the influence of sea depth is investigated; the dynamic response of a drillstring-riser system drilling in deep water is obviously different from the corresponding condition drilling in shallow water. In order to maintain the drillstring-riser system work in a safe condition, the operations, such as thickening the riser wall, enhancing the control of the top drift, removing a part of buoyancy modules, decreasing WOB, and increasing the top tension of the riser, are suggested to be applied.

This study examines the spatial spillover effects of transportation infrastructure on regional economic growth, utilizing panel data from 31 provincial-level administrative divisions in China from 2003 to 2022. Using the spatial Durbin model (SDM) and three distinct spatial weight matrices—0–1 adjacency, spatial economic–geographical nested, and GDP-based economic distance matrices—this study comprehensively analyzes the multifaceted impacts of transportation infrastructure. The results show that transportation infrastructure significantly promotes economic growth in both local and neighboring regions across all spatial weight matrices. The total effect is most pronounced in geographically proximate regions, with a coefficient of 7.845 (p < 0.01). Regions with similar economic development levels also show strong collaborative effects, with a coefficient of 2.074 (p < 0.01), although the marginal effect of transportation infrastructure diminishes. Furthermore, adjustments in industrial structure and innovation inputs demonstrate a short-term inhibitory effect on economic growth, highlighting the need for synchronized development of transportation infrastructure alongside industrial and innovation policies. This study incorporates multi-dimensional spatial weight matrices to systematically reveal the direct and indirect impacts of transportation infrastructure on regional economies, providing essential empirical support for regional coordination and infrastructure investment policies. The findings offer valuable insights for infrastructure planning in other regions, particularly in formulating policies that promote cross-regional economic cooperation and optimize resource allocation. [ABSTRACT FROM AUTHOR]

In the context of achieving certain results in rural revitalization and karst desertification control, promoting the realization of eco-product value to promote the rural revitalization strategy has become a hot topic in China. The importance of eco-product value has been raised to an unprecedented level, confirming that the realization of eco-product value is an important way to promote rural revitalization and ecological civilization construction in desertification areas. This study reviewed 489 relevant documents on the realization of eco-product value and conducted a statistical analysis. The analysis results show that (1) the number of published related documents is generally on the rise, indicating that after the policy was proposed, research in this field has received high attention from the academic community; (2) the research content mainly focuses on five aspects: eco-product value accounting, eco-product value realization, eco-industry, and theoretical attributes of eco-products; (3) the research area is concentrated in the demonstration pilot areas of China's eco-product value realization; and (4) combined with the above results, this paper summarizes the concept and connotation of eco-products, the value accounting of ecological products, the mechanism and path of the value realization of eco-products, the ecological industry, the landmark achievements of home and abroad, and the scientific problems to be solved, so as to better serve the karst area and promote the revitalization of rural areas. [ABSTRACT FROM AUTHOR]