Aiming at the problem of high water content and low degree of recovery of low permeability heavy oil reservoir in Guan128 block of Dagang Oilfield, the microscopic seepage law and residual oil characteristics of viscosity reducers flooding were studied through indoor experiments, and the planar wave and characteristics and residual oil distribution law were quantitatively analysed with the help of AI intelligent recognition. The experimental results show that after the viscosity reducer emulsification of crude oil, the emulsion aggregates and can block the water-driven flux channels, the advantageous transport channels of oil droplets increase, improve the wave and reach coefficient, and reduce the oil saturation. AI image identified pore throat droplets of oil, the wall membrane oil, the residual oil in the dead corner and the residual oil without wave and flake oil and other types of residual oil distribution, and the formation mechanism was analyzed, and measures of surfactants injection and encryption of the network of wells were put forward, and the blocking of high seepage channels was adjusted. Adding viscosity-reducing agent system can reduce the starting pressure gradient and improve the fluidity of heavy oil. After the conversion of water drive to chemical drive, the oil washing effect of residual oil in the pores and throat and residual oil in the dead space is improved, and the recovery rate is increased by 15.28%. The research results provide important theoretical reference for the research on the mechanism of efficient oil enhancement and field application of viscosity-reducing agent injection in the late stage of water-drive development of low-permeability heavy oil reservoirs.

The rapid development of new energy vehicles has made the industry’s requirements for high-performance automotive motors continue to increase. Hybrid excitation motor is a new type of motor. The hybrid excitation motor combines the advantages of permanent magnet excitation and electric excitation, and has excellent regulation and reliability. A parallel claw-pole hybrid excitation motor structure was proposed. The magnetic circuit of the hybrid excitation motor was optimized by means of parallel axial excitation of permanent magnet and electric excitation device. On this basis, the parametric simulation of the thickness of the claw pole side plate and the large end of the excitation bracket of the motor was carried out respectively, and the average torque of the motor before and after optimization was simulated according to the optimal structure. Finally, the mechanical characteristic curves of the parallel claw-pole hybrid excitation motor and the permanent magnet synchronous motor were compared and analyzed. The results show that the parallel claw-pole hybrid excitation motor broadens the operating range of the motor by 17.24% on the basis of maintaining the torque performance, and improves the mechanical properties and adaptability of the hybrid excitation motor.

To further improve the transmission performance of non-circular gear pair, a new helical non-circular gear with point contact was proposed based on the meshing principle of gears. Mathematical model of helical non-circular gear with point contact was constructed. Geometric kinematic relationships between the pitch curve and tooth profile curve for helical non-circular gear with point contact under spatial coordinate system were deduced. Tooth surface design of the gear was completed. Three-dimensional solid models of helical non-circular gear pair with point contact was established by using the convert-tooth shape method. The dynamic simulation model of helical non-circular gear with point contact was established. The dynamic meshing forces of the new gear pair and general involute non-circular gear pair under the same conditions were analyzed. Meshing characteristics of helical non-circular gear with point contact under different working conditions were also obtained. The tooth surface contact state and contact stress of point contact non-circular gear and involute non-circular gear under the same parameter and working condition were compared and analyzed. Research results provide an important theoretical support and reference value for the design and application of non-circular gear pair.

In order to solve the technical problem of insufficient reliability and life of rotary seal under the coupling effect of high pressure and high speed and medium corrosion, experimental research on rotary lip seal was carried out, a high-speed rotary lip seal test bed with pressure was designed and built, leakage and friction torque characteristic tests of lip seal were carried out, simulation calculation of lip seal was carried out, and a new type of seal with low friction coating was innovatively proposed. The temperature rise and torque comparison test of traditional seal and spraying new seal at different speeds were carried out. The experimental results show that the lip spraying tetrafluoroethylene (PTFE) material can effectively reduce the temperature rise of the seal. When the rotational speed increases by 1 000 r/min, after reaching the heat balance temperature, the temperature rise of the spray lip seal is 2.4 °C lower than that of the traditional lip seal. Under the pressure condition, the temperature of the coated lip seal is about 3.48 °C lower than that of the traditional lip seal. Under the condition of high speed and poor lubrication, the temperature of the spray lip seal is about 4.61 °C lower than that of the traditional lip seal, but the sealing torque increases by about 0.03 N·m. The sealing performance is evaluated from two aspects of sealing temperature rise and sealing friction torque, which provides theoretical support for solving the technical problems of high parameter rotary seal.

In order to improve the traffic efficiency of aircraft routes in areas affected by strong convective weather and optimize the diversion path of aircraft under the influence of strong convective weather, a multi-objective diversion path planning method based on the non-dominated sorting genetic algorithm III(NSGA-III) was proposed. By constructing a flight environment model and delineating flight restricted areas according to airspace conditions, and on this basis, focusing on the impact of strong convective weather in the area where the aircraft was diverted, the aircraft operation cost was the lowest, the diversion angle was the smallest, and the non-linear coefficient was the smallest, with the goal of minimizing the impact of weather, using NSGA-III to comprehensively considered factors such as safety and economy and other factors, a multi-target diversion plan for a certain airspace route under severe convective weather was carried out, and simulation analysis was conducted. The research results show that NSGA-III can comprehensively consider the four proposed goals and calculate multiple effective alternative diversion paths. Under the conditions of selecting two diversion points and taking into account the economy and rationality of the operation while ensuring the safe operation of the aircraft, a total of 91 alternative routes are available.

Predicting the emission reduction potential and cost of sustainable aviation fuel (SAF) that aligns with China’s national conditions is essential for advancing the SAF industry and achieving carbon neutrality goals. Based on the principles of international comparability and independent controllability, a lifecycle carbon emission reduction model was developed for two technological pathways: hydroprocessed esters and fatty acids (HEFA) and Fischer-Tropsch (FT). This model forecasted the emission reduction and cost associated with SAF in China’s civil aviation sector from 2025 to 2060.The results indicate that the HEFA pathway, which is suitable for implementation between 2025 and 2030 using waste oils as feedstock, achieves a carbon emissions reduction of 61.3 kgCO_2e/GJ, contributing to an overall reduction of 84.4%. This associated cost ranges from 0 to 1 025.9 CNY/tCO_2e when compared to traditional aviation kerosene. In contrast, the FT pathway-primarily developed between 2030 and 2060 utilizing municipal solid waste as raw material yields the highest carbon emissions reduction at 68.4 kgCO_2e/GJ. Furthermore, routes employing agricultural or municipal solid waste exhibit lower abatement costs than those utilizing forestry waste. Considering China’s specific national conditions, it is determined the FT route utilizing agricultural waste as feedstock is more appropriate for development as the main SAF production technology after 2030 due to its abundant raw materials and comparatively lower abatement costs. Projections suggest that by 2060, reductions in China’s civil aviation SAF could reach approximately 17 177 million tons to 19 819 million tons. From a possible scenario spanning from 2025 to 2060, it is estimated that cumulative carbon abatement costs will amount to between 11 063 to 45 828 billion CNY, this corresponds with a marginal carbon abatement cost ranging from 220 to 697 CNY/tCO_2e.

In order to investigate the durability of fibergypsum-based cementation material, a composite material was prepared byincorporating polypropylene and ramie fibers into high-strength gypsum,fly ash, and slag in a ratio of 44:34:22. Sodium methylsilicate wasutilized for waterproofing the fiber gypsum-based cementitious material,and the effects of freeze-thaw cycles on its softening property, waterabsorption, and mass loss were studied after 5,15,25,45, and 90 daysunder the combined action of ${\mathrm{H}}_{2}{\mathrm{{SO}}}_{4}$ or $\mathrm{{NaOH}}$ corrosion andfreeze-thaw. Freeze-thaw strain testing, flexural and compressivestrength testing, as well as industrial computed tomography(CT) scanningwere conducted. The results indicate that fibers can mitigate bothelastic and plastic deformation of the gypsum-based cementitiousmaterial during freeze-thaw cycles. Furthermore, under the combinedeffect of acid-base corrosion and freeze-thaw cycles, NaOH causesgreater damage than ${\mathrm{H}}_{2}{\mathrm{{SO}}}_{4}$ does.After undergoing 90 days of freeze-thaw cycling with sodiummethylsilicate treatment applied to it, the flexural and compressivesoftening coefficients increase by 0.28 and 0.13 respectively comparedto specimens without waterproofing; meanwhile water absorption ratesdecrease by 1.56% while mass loss rates decreased by 9.52%. Asfreezing-and thawing times increase, pore development in specimens isstill dominated by small holes, and crack diameters are mainly between ${0.1}\sim 2\mathrm{\;{mm}}$ .

In response to the shortcomings in the construction of temporary support for tunnels, a assembly of temporary support was proposed, and the new structure was studied from the aspects of temporary support shape, assembly structure, and stress deformation. Taking the Shaojiatang Tunnel as the background, on-site monitoring data was collected and compared with traditional temporary support structures using finite element software. It can be concluded that excavation of the tunnel’s rear tunnel will have adverse effects on the deformation of the previous tunnel. Vertical temporary support has better control over the left and right arch waists, surface settlement, and total convergence deformation of the tunnel. Compared with traditional curved structures, it decreases by 16%, 20%, 55%, and 14%, respectively. Moreover, vertical temporary support can restore stability faster and shorten the dismantling distance. By using vertical temporary support, the initial support force of the tunnel is smaller and safer compared to the curved support, and the maximum vertical and lateral stresses are reduced by 58% and 73%, respectively. The mechanical characteristics of temporary support local structures were simulated using ABAQUS software. The results show that the forces and deformations of both prefabricated vertical and traditional temporary support structures can meet the requirements of the specifications. However, prefabricated temporary support structures have more advantages in construction efficiency and economic benefits, and choosing prefabricated temporary support is more suitable.

In order to speed up the engineering progress, early strength additives are usually added to improve the early strength of cement grout. Calcium chloride, sodium sulfate, triethanolamine, synthetic calcium formate, HR-SA1 and other early strength additives were selected, the flowability, shrinkage rate, and compressive strength of cement slurry under the action of different early strength agents were explored through indoor experiments. In this way, the influence of different types of early strength agents on the early physical and mechanical properties of cement slurry were revealed. The results show that all early strength agents can meet the needs of on-site grouting requirements, ensuring that the fluidity of the cement slurry can be stable for a long time. The flowability of the synthesized calcium formate-based cement slurry significantly increases within 60 minutes, indicating a notable retarding effect. The fluidity of the other early strength agents cement slurry slightly increases within 60 minutes, but the amplitude is not significant. The compressive strength of (HR-SA1)-cement slurry specimens at all ages is significantly higher than that of ordinary cement slurry specimens, while the other four early strength agents have no significant effect on improving the compressive strength of cement slurry. The average shrinkage and shrinkage rate of (HR-SA1)-cement slurry specimens after final setting are very low, far lower than the average shrinkage and shrinkage rate of other early strength agent cement slurry specimens. It is verified by the construction site of prestressed anchor cable of a subway station in Qingdao City. The test values of the physical and mechanical properties of cement slurry are basically consistent with the results of laboratory test, which lays a foundation for the popularization and application of HR-SA1 early strength agent in practical engineering.

Microbial induced calcium carbonate precipitation (MICP) technology is an emerging green reinforcement technology for geotechnical engineering, which has a good application prospect in the reinforcement of loess slopes. The reinforcement of loess by MICP is affected by a variety of factors, in addition to the external environment, material properties and reinforcement methods and other factors, the calcium source, the concentration of binder, the age of the maintenance and the maintenance methods also play a decisive role in the microbial reinforcement of loess. The loess in Longxi area was taken as the research object, bacillus subtilis-induced calcium carbonate precipitation technology was adopted to consolidate loess, and a comparative experimental study on the shear strength of MICP-consolidated loess under the conditions of different calcium sources, binder concentration, age of maintenance and maintenance methods was carried out. The results show that the MICP technology is more effective in consolidating loess specimens when the calcium source is calcium chloride, the binder concentration is 1.0 mol/L and the specimens are cured for 7 d. The cohesion and internal friction are increased by 4.95 and 1.34 times, respectively, compared with the vegetal loess soil. The research results have certain reference value for the roadbed reinforcement and slope management in the Loess Plateau area.