Development evaluation of nature reserves under China’s forestry department: A spatiotemporal empirical study at the province level

It is important to evaluate the development level of nature reserves. In this study, we aimed to assess the development level of nature reserves under the administration of China’s forestry department in 31 provincial-level regions from 2005 to 2017 (excluding Hong Kong Special Administrative Region, Macao Special Administrative Region, and Taiwan Province). For this purpose, we analyzed the spatial and temporal evolution of nature reserve development in different regions using projection pursuit and spatial econometric methods. In terms of temporal distribution, the development level of nature reserves has been steadily improving, and the growth rate showed the trend of “strong fast” and “weak slow”. However, the development gap among different provinces is large. In terms of spatial distribution, the development of nature reserves presented the characteristics of “high in the west and low in the east” and “high in the north and south and low in the middle.” The endowment of natural resources, scientific research, and investment has a considerable effect on the development level of nature reserves. This study provides suggestions for the differential construction and sustainable development of nature reserves in China.

FEATURES OF CALCULATION OF CENTRIFUGED AND VIBRO-CENTRIFUGED REINFORCED CONCRETE STRUCTURES BY DIFFERENTIAL CONSTRUCTION CHARACTERISTICS OF CONCRETE

This article raises one of the most popular questions: evaluation of calculations of differential design parameters of centrifuged and vibro-centrifuged concrete. It is established that various layers of concrete of annular cross-section in the process of centrifugation and vibro-centrifugation are influenced by forces that differ from each other in the magnitude of the impact. This leads to completely different indicators of concrete layers in density, strength, deformability and modulus of elasticity. Centrifugal and centripetal forces are the main factors that are worth to pay attention to and to use in the calculated dependencies as arguments. Therefore, in general calculations, which take into account the change in the structural parameters of concrete, it is advisable to use the structural indicators or their increase as functions, and as independent variables – the forces of inertia of rotation, which, in turn, are the dependence of the distance from the center of rotation and the angular velocity of rotation. As a result, the calculated dependencies are derived for the differentiated accounting of changes in all the characteristics of concrete necessary for calculating, which gives grounds to enter into the calculation of structures the strength and deformation indicators of concrete that differ in cross section, and to use the existing reserves of the bearing capacity of elements.