In order to improve the problem of easy cracking in the negative moment zone of the composite beam, the UHPC(ultra-high performance concrete)-narrow steel box composite beam structure was proposed, and the shear load capacity calculation method of UHPC-narrow steel box composite beam was obtained based on the ultimate equilibrium method and the sub-stacking method. In order to verify the accuracy of the calculation method, one normal concrete narrow steel box composite beam and three UHPC-narrow steel box composite beam specimens were designed with the thickness of UHPC layer and steel fiber as variables, and the test beams were subjected to mid-span reverse loading test to obtain the shear resistance of the composite beam under negative bending moment. The test results show that compared with the normal concrete narrow steel box composite beam, when the UHPC material is used in the wing slab, the crack distribution in the wing slab was more regular, and with the increase of the thickness of the UHPC slab, the crack distribution gradually shows the characteristic of vertical equidistant distribution, and when the thickness of the wing slab was kept constant and the thickness of the UHPC layer was increased by 50 mm, the yield load increases by 12.5% and the ultimate load increases by 8.3%, and the deflection value corresponding to the ultimate load is reduced by 22%. By analyzing the yield deflection as well as the ultimate deflection of each specimen, it can be seen that the yield deflection tends to increase gradually with the increase of UHPC airfoil thickness, and the proportion of the elastic phase of the combined beam keeps increasing. The comparison of the test data with the theoretical calculation results shows that the calculation results obtained by the sub-stacking method can more effectively reflect the contribution of UHPC layer, ordinary concrete layer, steel box, reinforcement and filled part of concrete to the shear load capacity, and the results are more accurate.

In order to analyze the effect of fan rotor blade leading edge erosion on the aerodynamic characteristics of the compression system for different internal and external culverting conditions, multilevel cascade calculations were used to investigate the changes in the aerodynamic characteristics of the compression system of a certain type of engine with large culverting ratio. The results show that the total pressure ratio, isentropic efficiency and channel flow rate of the engine compression system after leading edge erosion relatively decrease by 0.18%, 0.879% and 0.972%, respectively, under the peak efficiency point working condition. For fan rotor blades, leading edge erosion leads to a decrease in the slope of the surface static pressure coefficient curve in the axial 0~24% interval of the surface static pressure coefficient curve at the height of 95% of the blades under near-surge point conditions in the outer culvert channel, with a decrease in static pressure, and an increase in the slope in the axial 24%~40% interval, which reduces the loading of the blade, reduces the pressurizing capacity, and moves the surge wave forward.In addition, leading edge erosion increases the angle of attack of the overall fan blade at the near-surge point of the outer culvert by about 2°, resulting in changes in blade aerodynamic efficiency and stall margin, which deviates from the original blade design.

The dynamic modulus of asphalt mixture is an important parameter in the design of asphalt pavement. Extracting material characteristics, dynamic modulus, and phase angle information from a large amount of asphalt concrete datasets using integrated methods is of great significance for optimizing the performance of asphalt pavement. The extreme gradient boost (XGBoost) model aggregated a series of decision tree models through weighted summation to construct a powerful prediction model, while optimizing the loss function to minimize prediction errors. In order to further improve the accuracy of dynamic modulus and phase angle prediction, heuristic algorithms were used to optimize the model. Initially, the basic model was initialized based on samples and the gradient of the loss function of the training data was calculated. Subsequently, XGBoost utilized gradient details to construct a decision tree model, optimized leaf node weights, and updated the model’s predictions through weighted summation. During this process, heuristic algorithms are used to optimize the optimal parameters of the entire XGBoost model. The experimental results show that the improved XGBoost model outperforms the original model in all performance evaluation indicators, improving the accuracy of predicting the dynamic modulus and phase angle of asphalt mixtures.

To evaluate the safety of navigation flight task scheduling schemes in forest fire rescue, safety evaluation indicators for navigation rescue task scheduling schemes were proposed by detecting the flight path conflicts of various general aircraft. Using an airspace grid model to model the rescue flight environment, and planning the rescue flight paths of aircraft with different performance constraints based on their respective task scheduling schemes, and conducting trajectory conflict detection to evaluate the safety of the task scheduling scheme. The simulation results show that this method has a 53.8% improvement in time efficiency compared to the direct conflict detection algorithm, and a 6.7% improvement in accuracy compared to the efficient spatiotemporal synchronous route conflict detection method. It can be seen that this method can efficiently and accurately predict track conflicts in rescue flights and evaluate the safety of task scheduling schemes, providing effective decision support for navigation rescue command and scheduling work.

ARGs(antibiotic resistance genes) as emerging environmental pollutants threaten human health, and studies show that secondary effluent from sewage treatment plants is an important source of ARGs in the environment. Ozone pre-oxidation combined with PAC(powdered activated carbon) and UF(ultrafiltration) was used to treat the secondary effluent from the wastewater treatment plant, and the factors and mechanisms of O₃ dosage, pH, and temperature on the removal of different forms of ARGs in the secondary effluent were investigated. The results show that ARGs could be more effectively removed by PAC adsorption and UF after oxidative inactivation by O₃; under the condition of optimal O₃ dosage (2.0 mg/L), the combined O₃-PAC-UF process could remove different types of ARGs (tetA, tetC, tetG, sulI, sulII) and other pollutants (intⅠ1, 16S rRNA) from the secondary effluent. The removal of different types of ARGs (tetA, tetC, tetG, sulI, sulII) and other pollutants (intⅠ1, 16S rRNA) by the combined process is 10^2.67~10^3.92 copies/mL, and the removal of cellular and free ARGs is significantly enhanced; the elevated pH and lower temperature facilitate the removal of ARGs; the direct oxidation of O₃ molecules dominate the removal of ARGs in the secondary effluent. In conclusion, ozone combined with PAC and UF can effectively remove antibiotic resistance genes from secondary effluent.

Oil booms play a vital role in dealing with oil spills on water. Aiming at the single problem of existing oil booms in fast-flowing rivers, a new type of double-layer mesh fence was designed for oil spill recovery in fast-flowing rivers based on the parameters of traditional oil booms. Based on the mainstream CFD (computational fluid dynamics) software FLUENT, a two-dimensional numerical flume model was established to simulate the transient distribution of oil and water under the action of the new oil containment boom with VOF (volume of fluid) as the computational model, and the volume of oil intercepted was used as the monitoring data to explore the direction of optimizing the oil containment performance of the oil containment boom. Monitoring data was used to explore the optimization direction of oil containment performance of the oil containment boom. The results show that the optimised oil containment boom has a grid radius of 30 mm and a porosity of 0.3. Compared with the traditional boom, the new oil containment capacity of the new oil containment boom is better than that of the traditional boom, which provides an effective reference for the design of oil containment boom for fast-flowing rivers.

With the continuous integration of urban Bridges into a variety of traffic forms, various traffic vehicles and pedestrians interfere with each other, affecting the safety and comfort of pedestrians. To research the pedestrian response on single-level rail-cum-road bridges, a pedestrian-road vehicle-train-bridge coupling vibration model was established. The acceleration difference between the bridge panel and pedestrian SMD model was researched, and the influence of trains and road vehicle passing the bridge in different ways on pedestrians was calculated. The results show that, compared with bridge panel, the amplitude of acceleration fluctuation of pedestrian SMD model is smaller, but the walking pedestrian model may experience abrupt and significant acceleration peaks. Each moving subsystem in the coupling model has a speed-sensitive interval, in which the pedestrian acceleration increases significantly. The further vehicles are away from the bridge center, the greater the acceleration of pedestrians become. When train and road vehicle pass the bridge simultaneously, the peak acceleration of pedestrian caused by them will be superimposed, and the peak acceleration caused by road vehicles increases significantly due to the train.

In order to detect the abnormal working conditions such as overpressure and leakage, that may occur in pipelines and installations in the process of natural gas regional production, the current industrial control and alarm systems cannot accurately reflect the real state of the equipment, and the single-parameter early warning has a higher rate of error judgement, which is insufficient in practicality. A collaborative prediction and warning method for process parameters related to upstream and downstream stations in a natural gas production area was tested. Aiming at the characteristics of natural gas region with many stations, complex production process and diverse monitoring data, firstly, the parameters of each station were downgraded to extract the key process parameters of each station. Then, the key parameters are evaluated and grouped by correlation, and a multivariate nonlinear lasso regression prediction model was established with the highly correlated parameters in the same group as the independent variables. At the same time, a long and short-term memory prediction model was established for the key parameters, and a comparison analysis of the prediction results was performed to determine the dynamic prediction and early warning of natural gas production. Comparative analysis of the prediction results of the two models was used to determine the dynamic thresholds for coordinated early warning of regional production. The results show that the method can not only effectively reduce the misjudgment of single-value anomalies, but also locate the anomalous stations and points, which is of high practical value.

In order to improve the trajectory tracking accuracy and stability of the aircraft in the traction process, taking the four-wheel steering aircraft traction system as the research object, the kinematics model of the aircraft traction system is established, and the four-wheel steering trajectory tracking control method of the tractor based on the model predictive control was proposed. Taking the double lane changing condition as the reference trajectory, the motion control simulation model of the aircraft traction system was built in MATLAB/Simulink, and the four-wheel steering trajectory tracking controller was established by combining the speed of the tractor and the angular distribution relationship of the four wheels. The controller was compared and analyzed with the traditional PID control to derive the superiority of the controller, and the tractor four-wheel steering and front-wheel steering trajectory tracking controllers were simulated and compared and analyzed at the speeds of 1.5 m/s, 3 m/s and 4 m/s, respectively. The designed controller was simulated and verified by changing the initial positional attitude of the aircraft traction system at a speed of 1.5 m/s. The results show that at three different speeds, the airplane lateral error, the heading angle error, and the tractor heading angle error under the four-wheel steering trajectory tracking control of the tractor are smaller than those under the front-wheel steering trajectory tracking control. In the case of initial deviation, the four-wheel steering trajectory tracking controller can enable the aircraft to complete the correction of the initial deviation in time, reduce the trajectory tracking error, and at the same time improve the stability of the aircraft's traction system in the driving process.

In order to scientifically assess the operational efficiency of airport surface movements, a departure flight taxi time prediction method considering runway and taxiway system configurations was proposed. Firstly, the definition of surface taxi time was provided, and an analysis of the historical operational data at the airport was conducted to identify more accurate factors influencing surface taxi-out time. Based on the conclusions drawn from correlation analysis, a random forest prediction model for departure flight surface taxi time was constructed. The method was illustrated using actual operational data from Shijiazhuang Zhengding Airport and Shenzhen Bao'an Airport, analyzing the characteristics of surface movement time under different runway system configurations. The results indicate that: Apart from taxi distance, the correlation results of factors influencing surface taxi-out time at airports with different runway and taxiway system configurations are generally consistent. When considering the same factors, the prediction of surface taxi time is better for single-runway airports compared to dual-runway airports. Surface taxi time at single-runway airports approaches unimpeded taxi time, while at dual-runway airports, there is a significant difference from unimpeded taxi time. The research findings are of significant importance for enhancing airport surface operation efficiency and achieving energy savings and emissions reduction.