Simulation of Water Use Dynamics by Salix Bush in a Semiarid Shallow Groundwater Area of the Chinese Erdos Plateau

This study analyzed the water use of the Salix psammophila bush in a semi-arid area in northwest China using a Hydrus-1D model. The model incorporated the effect of thermally driven water flow coupling liquid water, water vapor and heat transport. The model was calibrated and validated using hourly field measurements of soil water content and temperature at different depths for a growing season of 154 days. Furthermore, another Hydrus-1D model was established to simulate environments with decreased heat, rainfall or temperature and an increased leaf area index using calibrated and validated parameters. Our results show that upward and downward thermally driven water vapor fluxes account for 0.11% and 0.28%, respectively, of the corresponding direction of total water flux during the bush’s growing season. Although the vapor flux is very small, simulations incorporating heat flow revealed alterations in the temperature and pressure head gradients over the root zone, especially during dry periods. Consequently, the cumulative contributions of groundwater to evapotranspiration (ETg) with heat flow and without heat flow were 26.9% and 40.6%, respectively, during the simulation period. Therefore, the cumulative contribution of groundwater to ETg is overestimated when heat flow is excluded. Thus, we recommended that heat transport be incorporated when evaluating ETg in arid and semi-arid areas

Microbial Community Structure and Predictive Functional Analysis in Reclaimed Soil with Different Vegetation Types: The Example of the Xiaoyi Mine Waste Dump in Shanxi

We explored the characteristics of soil bacterial communities and their ecological functions under different types of vegetation reclamation in open-pit mines on the Loess Plateau, which is the guiding significance for the selection of vegetation and the improvement of restoration effect in mining areas. The research object was to reclaim the soil of the aluminum mine waste dump in Xiaoyi County, Shanxi. The soil characteristics were measured under different types of vegetation reclamation. The soil bacterial community under different vegetation reclamation was measured using the 16S rRNA gene high-throughput sequencing technology. The ecological function was predicted using the PICRUSt method. The correlation between soil physical and chemical properties and bacterial community structure and function was analyzed. From the results, (1) the bacterial compositions of the reclaimed soil samples were 33 phyla, 90 classes, 121 orders, 207 families, 298 genera, and 140 species. The abundance and diversity of the soil microbial community showed the rule of yellow rose > lespedeza and sweet wormwood herb > alfalfa. (2) Proteobacteria were the dominant bacteria in alfalfa and sweet wormwood herb samples, accounting for 36.09–43.36%. Proteobacteria and actinobacteria were the dominant bacteria in the yellow rose and lespedeza samples accounted for 53.34–53.39%. α-Proteobacteria, actinobacteria, and β-proteobacteria were the dominant bacteria of the four vegetation types. The relative abundance of the α-proteobacteria and β-proteobacteria was positively correlated with soil organic carbon (SOC) and negatively correlated with soil total kalium (TK). Actinobacteria were positively correlated with available kalium (AK) and negatively correlated with SOC and total nitrogen (TN). (3) There was no difference in the primary functions of the soil bacterial community after the reclamation of different plants, and the main functions were metabolism, genetic information processing, and environmental information processing, with the function abundance accounting for 81.52%. (4) The abundance of functional genes in the metabolism of other amino acids, folding, sorting, and degradation and glycan biosynthesis and metabolism were relatively rich in the rhizosphere soil of yellow rose. The abundance of functional genes in signal molecules and interaction, transport, and catabolism in the rhizosphere soil of lespedeza was the highest. The abundance of functional genes in carbohydrate metabolism, translation, and energy metabolism in the rhizosphere soil of alfalfa was the highest. Therefore, there were significant differences in the structure and function of rhizosphere soil microbial communities among yellow rose, lespedeza, sweet wormwood herb, and alfalfa, and they were also affected by the soil properties. Hence, we concluded that the differences and diversity of soil microbial structure and function can help select plants for the sustainable development of soil remediation in mining areas

Dynamic Pricing for Resource Consumption in Cloud Service

This paper studies dynamic pricing for cloud service where different resources are consumed by different users. The traditional cloud resource pricing models can be divided into two categories: on-demand service and reserved service. The former only takes the using time into account and is unfair for the users with long using time and little concurrency. The latter charges the same price to all the users and does not consider the resource consumption of users. Therefore, in this paper, we propose a flexible dynamic pricing model for cloud resources, which not only takes into account the occupying time and resource consumption of different users but also considers the maximal concurrency of resource consumption. As a result, on the one hand, this dynamic pricing model can help users save the cost of cloud resources. On the other hand, the profits of service providers are guaranteed. The key of the pricing model is how to efficiently calculate the maximal concurrency of resource consumption since the cost of providers is dynamically varied based on the maximal concurrency. To support this function in real time, we propose a data structure based on the classical B+ tree and the implementation for its corresponding basic operations like insertion, deletion, split, and query. Finally, the experiment results show that we can complete the dynamic pricing query on 10 million cloud resource usage records within 0.2 seconds on average

Thermal simulation of microelectrode machining process during block electrical discharge grinding

Electrical discharge machining is widely used in aerospace industries, semiconductor applications, micro-electromechanical systems, and other fields of the machining of micro-holes, micro-shafts, and micro-structures due to non-contact stress during the electrical discharge machining process. In the electrical discharge machining process, the machining precision of electrical discharge machining depends on the dimensional precision of the tool electrode, therefore, the machining process of microelectrode has attracted growing concern. In this study, a thermal model of the microelectrode machining process was proposed to simulate the formation process of microelectrode based on the temperature distribution during block electrical discharge grinding of the microelectrode process. According to the microelectrode machining process, the thermal model considers the main influential factors such as random distribution of discharge points, time-dependent discharge channel radius, Gauss heat source, phase transformation latent heat, etc. Through the thermal simulation analysis, the temperature distribution and the dynamic spark-erosion process of the microelectrode based on random repetitive spark discharges were obtained during block electrical discharge grinding of the microelectrode. Besides, it is found that the maximum temperature value and discharge crater volume of the electrode surface fluctuate and gradually decrease with the increase of discharge times. In addition, the effect of pulse width on the machining process of microelectrode was investigated by numerical simulation and block electrical discharge grinding of microelectrode experiment. The results indicated that the crater volume and the maximum temperature value on the surface of the microelectrode increased with the increase of pulse width. The formation process of microelectrode was considered a significant indicator to determine the machining precision and machining efficiency of the electrical discharge machining process

Comparison of Soil Bacterial Communities under Canopies of <i>Pinus tabulaeformis</i> and <i>Populus euramericana</i> in a Reclaimed Waste Dump

To compare the effects of different remediation tree species on soil bacterial communities and provide a theoretical basis for the selection of ecosystem function promotion strategies after vegetation restoration, the characteristic changes in soil bacterial communities after Pinus tabulaeformis and Populus euramericana reclamation were explored using high-throughput sequencing and molecular ecological network methods. The results showed that: (1) With the increase in reclamation years, the reclaimed soil properties were close to the control group, and the soil properties of Pinus tabulaeformis were closer to the control group than those of P. euramericana. (2) The dominant bacteria under the canopies of P. tabulaeformis and P. euramericana was the same. Proteobacteria, Actinobacteria, Acidobacteria, Chloroflexi, Gemmatimonadetes, Planctomycetes, Bacteroidetes, and Cyanobacteria were the dominant bacteria in the restored soil, accounting for more than 95% of the total abundance. The average values of the Shannon diversity index, Simpson diversity index, Chao 1 richness estimator, and abundance-based coverage estimator of the bacterial community in the P. euramericana reclaimed soil were higher than those in the P. tabulaeformis reclaimed soil. The influence of reclamation years on the bacterial community of samples is greater than that of species types. (3) The results of ecological network construction showed that the total number of nodes, total number of connections, and average connectivity of the soil bacterial network under P. euramericana reclamation were greater than those under P. tabulaeformis reclamation. The bacterial molecular ecological network under P. euramericana was more abundant. (4) Among the dominant bacteria, the relative abundance of Actinobacteria was negatively correlated with soil pH, soil total nitrogen content, and the activities of urease, invertase, and alkaline phosphatase, while the relative abundance of Proteobacteria and Bacteroidetes was positively correlated with these environmental factors. The relationship between the soil bacterial community of P. tabulaeformis and P. euramericana and the environmental factors is not completely the same, and even the interaction between some environmental factors and bacteria is opposite

Targeting the Influences of Under-Lake Coal Mining Based on the Value of Wetland Ecosystem Services: What and How?

Under the growing restrictions of the Chinese eco-environmental policies, the impact of under-lake coal mining on wetlands is receiving increasing attention from both coal mining enterprises and local governments. This paper focuses on the impact of under-lake coal mining on the Nansi Lake wetland from 1991 to 2021. Field measurements, resident surveys, and remote sensing inversion were comprehensively employed to quantitatively assess the impact. The calculation of the assessment indicators refers to the elastic coefficient, the information for which comes from four major categories of ecosystem service values (ESVs) and eight sub-ESVs. According to the results of the remote sensing interpretation and inversion, by 2021 the range had enlarged by 32.3 km2, and the water depth had increased by 1.9 m in the mining-disturbed area relative to 1991. The ESV fluctuations in the Nansi Lake wetland also exhibited a generally increasing trend over time. Our results show that the under-lake mining disturbs the ESVs, but the disturbance is not sufficient to result in significant consequences. Based on the data analysis, we suggest several well-directed, appropriate restoration strategies to achieve the desired objectives and target the response of the ESV changes. Such measures will help to relieve some of the anxiety and concern about the wetland changes caused by the under-lake mining