The Earth’s surface is a complex system involving mutual interactions of its many components, including mountains, rivers, forests, farmlands, lakes and grasses. The interaction and mutual feedback of chemical elements in Earth's surface layer can drive changes in chemical elemental distribution patterns. In this study, we evaluated the mechanisms and interactions driving the distribution patterns of macroelements, probiotics, halogens and heavy metals in soils in Southwest China, based on a systematic geochemical land-quality survey at a scale of 1:250000. The results showed that the parent material determines the natural state of chemical elements in land resources. Epigenetic geochemical dynamics reshapes the distribution patterns of chemical elements in top soil; biogeochemical processes drive the evolutionary trends of land quality; and human activities, such as mining, disrupt the natural evolution of chemical elemental distribution patterns. The establishment of an epigenetic geochemical dynamics theory allows the construction of a framework for understanding the Earth's surface layer and promoting technological innovations for the comprehensive geochemical investigation of land resources.
As an important part of smart grid, EVs have many advantages in energy saving and low pollution and become a research hotspot. Based on the wireless power transfer technology, dynamic power supply technology develops rapidly and can effectively reduce the battery capacity of EVs. This paper the issue on the optimal design of sectional dynamic power supply track has been investigates the optimal design of sectional dynamic power supply track. For the optimal design of sectional tracks, a mathematical model of the minimal average annual comprehensive cost has been set up and a novel Cellular Particle Swarm Optimization (CPSO) based on PSO and CA are proposed to solve the nonlinear optimization problem. The results of numerical simulation show that it is more reliable to obtain the optimal design by CPSO rather than by PSO. Furthermore, the minimal average annual comprehensive cost is 60 thousand Yuan produced by CPSO less than that by PSO.
Pile foundations are widely adopted in the Qinghai–Tibet Railway. The pile’s bearing capacity must be influenced the trends of global warming, rising foundation soil temperatures, expanding active layers, ground ice melting, etc. Thus, the pile’s long-term bearing capacity must be understood, and methods for evaluating its stability in permafrost regions must be developed. The bearing capacity of a pile foundation in a permafrost region is caused by the freezing strength of the pile–soil interface and support force at the pile bottom. Based on the formation mechanism of the bearing capacity of pile foundations in permafrost regions, the stability ratio of the freezing area and the freezing strength between the pile and soil are proposed to evaluate the thermal stability of the pile’s bearing capacity in permafrost. Using the method, a bearing capacity study on a single pile in typical moist permafrost and two piles in a permafrost region where warm groundwater is underground is performed. Compared with the field-measured value, the evaluation method proves to be correct and effective. Using the two parameters dependent on the soil–pile interface temperature, the effect of the thermal stability of pile bearing capacity may be described intuitively. Thus, both parameters are conducive to the analysis of pile bearing capacity formation mechanism in permafrost.
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