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.

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 this paper, the anti-invasion performance of the perimeter wall between the test pressures of the completion tool is analyzed. According to the conditions of the downhole tool pressure test such as test medium, test temperature, test pressure, and the possibility of dislodging the parts during the test, a combination of three types of perimeter wall structures is proposed: single steel plate, double steel plate + timber interlayer, and double steel plate + concrete interlayer. To meet the test pressure requirements, the three types of perimeter wall structure combinations are analyzed to determine more conservative structural dimensions by means of finite element simulation calculations and analyses, and the results of the analysis from the simulation of the Combination 1 structure are verified by means of the impact test.

Regarding the increasing number of IoT devices and the trend towards miniaturization, which require high concurrent transmission performance and low energy consumption, an improved MAC(media access control) layer CSMA/CA(carrier sense multiple access with collision avoidance) protocol design is proposed based on physical layer MIMO(multiple input multiple output) technology. It simplifies the complexity of executing the CSMA/CA protocol on terminals and employs MIMO to achieve concurrent access for multiple terminals through cross-layer design, and allows terminal devices to easily and conveniently access the network system. An analysis of the throughput performance of the proposed protocol was presented, and its effectiveness and the accuracy of the theoretical analysis were verified through simulation, which not only provides a theoretical supplement to the redesign of the CSMA/CA protocol but also offers practical guidance for engineering applications.

The standards and processes of third-party testing and consulting services was optimized by summarizing and analyzing the shortcomings,the measures that need be improved and on-site feedback and other comprehensive elements that exist during the work period. The work standards was further optimize and implemented, benchmark was conducted to find deficiencies and make up for them. Finally, based on the optimized and improved work standards, constructive rectification suggestions and standard requirements are proposed from inspection ideas to results display, while providing feedback on issues, violation clauses are listed. This innovative mode can not only effectively help rectify the hidden dangers on the project site, but also achieve the effect of point-to-point technical disclosure, thus reflecting the professional services and progressiveness management of third-party testing.

With the rapid construction and development of comprehensive transportation hubs, the air-rail intermodal transportation model has brought more convenience to passengers’ travel. Accurately understanding the air-rail intermodal passenger flow is crucial for improving the overall transportation service quality and ensuring transportation safety. A two-stage model combining particle swarm optimization-random forest model (PSO-RF) and Logit model is used to predict the passenger flow of travel paths in the context of air-rail intermodal transportation between urban agglomerations. Take one-way “Shifting from Railways to Aviation” as an example. In the first stage, the average daily civil aviation passenger flow of travel routes was predicted based on historical data by PSO-RF model. In the second stage, a behavioral survey was conducted through the airport outbound passengers to analyze the characteristics of passengers’ transfer mode and choice behavior. Then, a Binary Logit model of passenger travel choices was constructed based on the disaggregate theory, and the high-speed rail transfer sharing rate was calculated. Finally, the results of the two-stage model were combined to calculate the travel route passenger flow forecasts. The effectiveness and feasibility of the proposed method by constructing a case study from Shanghai to Chengdu neighboring urban agglomeration were validated. The results indicate that the accuracy of the two-stage model reaches 80.40%.

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 image processing technology and finite element simulation software based on ABAQUS were adopted to analyze the cracking damage and related influencing factors of asphalt mixture at the meso level. At the same time, zero-thickness cohesive force units were inserted at the asphalt mortar and aggregate-mortar interface to conduct finite element simulation of asphalt mixture SCB(semi-circular bending) test and analyze the cracking process of asphalt mixture at the meso level. The effects of pre-cut depth, specimen thickness and support distance on the cracking characteristics of asphalt mixture were investigated by using the load-displacement curve and fracture energy obtained from the cracking of the specimen. The results show that the deeper the prefabricated incision and the smaller the thickness of the specimen, the worse the anti-cracking performance of the specimen, and the anti-cracking performance increases first and then decreases with the increase of the distance between the supports. The anti-cracking performance of the specimen is the best when the distance between the supports is 80 mm.

The finite-element model was used to simulate the double I-steel and concrete composite beam bridge with a span of 4×35 meters in the approach bridge outside the dike of Shouchun Huaihe River Bridge.The results indicate that the impact factor of the steel beam increases with speed and then decreases, reaching a maximum at 60 km/h. In contrast, the impact factor of the bridge deck continues to rise with speed, exceeding the design value of the standard local impact factor by 91.67% at 120 km/h. Both the steel main beam and the bridge deck’s impact factors decrease with the increase in vehicle weight. Specific trends in the variation of impact coefficients with vehicle speed and weight are identified, the limitations of existing bridge design codes in accurately describing the actual dynamic response to vehicle loading is revealed, the importance of considering local dynamic effects in bridge design and evaluation is emphasized.

Taking the No.1 tunnel of an irrigation district as the engineering background, the waterproofing design principle of “blocking water and limiting drainage” was adopted to explore the influencing factors of external water pressure under the composite lining condition of isotropic shallow buried tunnels. A simplified model of composite lining was established to analyze and derive the analytical solution of the variation in external water pressure and seepage volume in relation to the surrounding rock's permeability, grouting layer, lining permeability and head. At the same time, the Midas finite element software was used to calculate the water pressure and seepage volume under different conditions to verify the reasonableness of the analytical solution. The study shows that the permeability and thickness of the grouting ring have a greater influence on the water pressure and seepage volume outside the lining, and the construction of the grouting ring should be emphasized. With the increase of the depth of the drainage hole into the rock, the water pressure outside the tunnel lining gradually decreases. Therefore, in the environment of high groundwater head, setting drainage holes on the tunnel is the best effective measure to reduce the external water pressure.