As China enters the middle stage of industrialization and modernization, both energy consumption and carbon emissions are growing, posing an increasingly serious challenge to sustainable development. The industrial sector is a major source of carbon emissions, and its structural optimization is crucial for reducing carbon emission intensity. Based on a sample of 30 provinces in China from 2005 to 2021, a dynamic panel threshold regression model was applied to treat provincial cooperation as a threshold value, and the mechanism of industrial structure optimization on carbon emission intensity was explored from two dimensions: rationalization and advancement of industrial structure. The results show that the rationalization and upgrading of the industrial structure have a significant negative impact on carbon emission intensity. However, the rationalization of industrial structure has a significant three-threshold effect on carbon emission intensity, and this negative effect shows a “V” type change trend on the whole. The upgrading of industrial structure has a single threshold effect on carbon emission intensity. The upgrading of the industrial structure will significantly promote the reduction of carbon emission intensity only when the provincial cooperation index is at least 2.013. The government should actively establish a cross-provincial cooperation mechanism to foster the coordinated development of inter-provincial industries and facilitate the extensive sharing of clean energy technologies, thereby promoting the transformation of the economy towards a green and low-carbon future.

On the basis of the actual structure of the linear hydraulic shock absorber of the medium and low speed maglev vehicle, the AMESim simulation model of the linear hydraulic shock absorber was established and verified. The maximum simulation error of the established hydraulic shock absorber simulation model is only 8.6%, and the reliability is high. Combined with the model of hydraulic shock absorber and maglev vehicle structure, the co-simulation model of shock absorber and vehicle system was established. From the perspective of dynamic optimization design, the installation quantity and layout position of lateral shock absorber were designed, and the influence of different installation modes of lateral shock absorber on the stability of maglev vehicle was discussed. The dynamic calculation results show that the installation modes of lateral shock absorber has little effect on the vertical stability of maglev vehicle.When 8 lateral shock absorbers are installed on the suspension frame of a single car, the vehicle stability is the best. When the suspension frame of a single car is equipped with 4 lateral shock absorbers, the vehicle’s ride stability performances takes the second place. When the lateral shock absorber is not installed, the lateral ride stability performances of the measuring points at the end of the vehicle exceeds the excellent limit.

Digital applications can achieve a win-win situation for economic and ecological benefits, which is particularly important for the green transformation of enterprises. Based on data from Chinese A-share listed companies from 2013 to 2022, how digital application affects corporate green innovation was explored by constructing a panel econometric model on the basis of measuring digital application indicators. Research findings indicate that digital applications are significantly positively correlated with green innovation. Under the examination of mechanism pathways, resource allocation plays a partial mediating role. After substituting key indicators, the conclusion remains valid. Enterprises should place great importance on digital applications, increase investment in research and development as well as digital infrastructure, and tap into the potential for green growth, among other things.

In order to ensure the efficient development and safe operation of deep water gas field and fully release the production capacity of each well area, the integrated steady-state model of “wellbore-wellhead-manifold-platform” was established. Based on the production plan, the research was carried out from the aspects of production verification, hydrate prevention and control, slug analysis and liquid carrying analysis. The results show that there are hydrate production risks in the whole life cycle in the east and west production routes. The maximum hydrate sub-cooling degree in the production route is less than -5 ℃ by optimizing the MEG injection amount in each well. The platform temperature of eastern and western logistics is -2.4~9 ℃, and the platform pressure is 1.3~11 MPa.The research results can provide technical guidance for the effective development of similar deep water gas fields in the future.

In order to solve the problem that the dynamic control performance of permanent magnet synchronous motor is poor when PI(proportional-integral) control strategy is used in vector control, and the motor parameters are easily affected by changes in external temperature and load, which leads to poor precision and responsiveness of the control motor, a model predictive control method is proposed to control the motor. This strategy uses the system model to predict the future input and state of the system, and directly calculates the control input by optimizing the objective function, which significantly improves the dynamic performance and steady-state accuracy. Moreover, with its strong ability to deal with nonlinearity and parameter changes, it can control the nonlinear system of permanent magnet synchronous motor well. According to the waveform diagram obtained by simulation, model predictive control is superior to PI control in dynamic response, anti-interference ability, low speed performance and robustness. Therefore, using model predictive control can effectively improve the control performance of permanent magnet synchronous motor.

Land-use change is an important part of global change and has a profound impact on the value of ecosystem services. Based on the land use data of 2010,2015 and 2020 in Dingbian County of Yulin City, the time and space was analyzed, the change of ecosystem service value was evaluated by equivalent factor method, and the spatial distribution characteristics was studied by Arcgis spatial analysis. The results show that the main land types in Dingbian County are cultivated land and grassland, in which the area of cultivated land and grassland is continuously decreasing, and the area of water area and construction land is increasing, and the degree of change of single land use type is shown as follows: water> construction land> wetland> grassland> woodland> cultivated land>unused land. ESV(ecosystem service value) from 2010 to 2020,2020 increased by 181 million yuan over 2010, in which the ESV increment of water is more significant, and the ESV of cultivated land and grassland decreases more. From the perspective of individual ESV, climate regulation and hydrological regulation are mainly used.

Lowering carbon emissions from tourism transportation is an important way to achieve the “dual carbon” goals. Based on spatial autocorrelation theory and the spatial Durbin model, a study was conducted on the spatiotemporal evolution and spatial spillover effects of carbon emissions from tourism transportation nationwide. The results indicate that from 2012 to 2020, the GDP of the tourism industry showed a good overall spatial autocorrelation, with industrial structure, green travel rate, and urbanization rate being the most influential factors on carbon intensity in tourism transportation. In terms of spatial spillover effects, there is a strong negative correlation between regional economic development levels and green travel rates with carbon emissions, while the spillover effects of urbanization rate show a contrary direct effect, demonstrating a positive effect, which indicates that the carbon reduction achieved with the increase in urbanization level has a marginal effect. Factors such as regional economic levels and advancements in environmental technology are also important means of reducing carbon intensity in tourism.

Due to the excessive mining and the lack of perfect and suitable mine restoration measures, some villages in Xintai area have coal goaf and karst collapse area. Through field investigation and public opinion survey, GIS(geographic information system)technology and Origin comprehensive three types of eight evaluation factors were used to evaluate the mine geological environment. With the engineering rock group stratigraphic lithology as the base map for the evaluation of the geological environment of Xintai major coal mining and hollowing township geological environment grade mapping, the results show that the mine environment in Xintai area is average. According to the evaluation results, targeted restoration and ecological management can be carried out in Xintai area according to the township as a unit. After using GIS and Origin and synergy matrixcalculation methods to evaluate the mine environment of each township in Xintai area, it is found that the mine geological environment quality of Wennan Town is relatively the worst, and the evaluation grade is poor, while the results of other township grades are average. Mine ecological restoration and land ecological utilization are important environmental protection measures, and it is recommended to restore the mine environment, organize land and carry out urban planning through vegetation restoration and greening, soil improvement and conservation, rational use of water resources, protection of biodiversity, land reuse and comprehensive development, and structural gradient restoration.The research method can be applied to the geological environment assessment of other mines.

High-quality development of rural tourism is an important tool for promoting rural revitalization. By analyzing 112 cases of poverty reduction in rural tourism, using theoretical coding and network text analysis to conduct relevant research and data revelation,the problems, measures taken, achievements and successes in the development of rural tourism in China were analyzed. On this basis, the strategies are proposed, including grasping the key of talents, promoting the integration of capitals, advancing the development of products, constructing the marketing pattern, improving the quality management, and building and sharing with hosts and guests, in order to provide certain reference for cracking the development dilemma of rural tourism, helping to promote the strategy of rural revitalization, and guiding the high-quality development of rural tourism.

In the construction of underground line reconstruction, pavement deformation has characteristics such as uncertainty and complexity. Therefore, the grey model was used to establish a prediction model for pavement deformation, and engineering examples were combined to verify its good accuracy. Given that the grey model can only predict the overall trend in deformation prediction and cannot reflect the volatility of prediction errors, prediction errors were processed to determine the upper and lower limit values of grey prediction, endowing the model with a certain prediction interval and changing the point prediction form. According to the intersection position of the deformation control line and the upper and lower limit curves of grey, the safety state of pavement deformation was divided to more reasonably judge the construction safety and provide reference for related projects.