A large number of towns in the western mountainous areas are within the hazard range of disaster chains such as landslides and debris flows, making the safety and disaster risk of mountain towns a key focus. The landslide-debris flow disaster chain in Lijie Gully, Lijie Town, Zhouqu County, Gansu Province was taken as a case study. Based on field investigations and remote sensing analysis, surface deformation was analyzed using interferometric synthetic aperture radar (InSAR) technology to determine the source of the disaster chain. The RAMMS dynamic model was then employed for the process and risk analysis of debris flows, followed by vulnerability and risk assessment. The research results indicate these as follows. The main subsidence areas within the basin are located at the edge and top of the ancient landslide area above Lijie Gully on the North Mountain, with the main cause of deformation being the seasonal freezing and thawing of soil. Based on the deformation results and remote sensing image analysis, the RAMMS dynamic model is used to conduct risk analysis of the Lijie Gully debris flow under three rainfall frequencies of 1%, 2%, and 5%. The comprehensive evaluation results show that the high-risk area accounts for 70.51%, largely distributed in the loose accumulation surface of the North Mountain landslide, the gully, both banks of the gully, and the accumulation fan at the gully mouth. Based on the risk and vulnerability assessment results, the high-risk area of the Lijie Gully debris flow accounts for 13.10%, mainly distributed in the gully mouth and along both sides of the gully where buildings are located. The large volume of loose accumulation above Lijie Gully is still in a continuous process of creeping-deformation-sliding, providing a large amount of material source for debris flows. The risk zoning results under different rainfall frequencies provide a reference for the disaster reduction of urban debris flows.

To ensure the safety of formwork engineering, and to accurately calculate the lateral pressure of fresh concrete on formwork, the problems of the formulas for lateral pressure of fresh concrete on formwork, provided by the national current standards, were analyzed firstly. Subsequently, based on the basic physical quantities of the international system of units, five key factors affecting the lateral pressure of fresh concrete on formwork were identified, the range of concrete slump was emphatically analyzed. By taking concrete slump as an important factor, it was directly introduced into the derivation. According to the relation between the depth of the concrete from the top of the placement to the point of consideration in the formwork, and the product of the rate of placing concrete in forms and initial setting time, formula for calculating the lateral pressure of fresh concrete on formwork was derived. Finally, the accuracy of the proposed formula was verified by using the experimental data in the literature. The results show that the proposed formula accords with the results of dimensional analysis, and the formula is more accurate in the application range of the formula provided by the national current standards. Moreover, beyond the applicable range of the formula provided by the national current standards, the proposed formula is of high accuracy and is generally safe.

In order to make rational and efficient use of biomass resources, considering the operating cost and environmental cost of each microsource unit, an economic dispatching model of combined cooling heating and power microgrid based on improved biomass gasification was designed. In order to solve the problem that the sparrow search algorithm is easy to fall into the local optimum, an improved sparrow search algorithm(ISSA) was proposed to solve the proposed model. First, a sine chaos map was used to generate spatially evenly distributed early sparrow populations. Secondly, a mutually beneficial learning mechanism was added and a mutation strategy was introduced to enhance the information sharing and global search ability among individuals in this field. Finally, by comparing the iterative results of ISSA, SSA, gray wolf algorithm, whale algorithm and marine predator algorithm, it is proved that ISSA has good optimization effect and stability. Through the analysis of typical simulation cases, the effectiveness of the ISSA algorithm in solving the economic dispatching problem of combined cooling, heating and power microgrid is verified.

The stiffly-expanded composite pile is a new type of composite pile formed by sinking rigid pile in cement soil mixing pile. In order to study its bearing characteristics in complex soft soil-sandy soil foundation, a numerical analysis model of rigid composite pile was established based on finite element software ABAQUS, with the effect of core pile length and diameter, soil-cement pile length, diameter and elastic modulus, as well as soil-cement and pre-stressed high-strength concrete(PHC) pile interface and soil-soil interface shear strength on the bearing performance was analyzed. The results show that the bearing capacity and economic advantages of the stiffened composite pile are obvious. The bearing capacity of composite pile increases with the increase of research parameters, but the improvement is limited by changing the research parameters beyond a certain range. With the increase of load, the slope of axial force distribution curve of composite pile increases, and the load proportion of PHC core pile is about 93.32%~95.40%. When the load exceeds 4 000 kN, the axial force of soil-cement pile increases sharply within the depth range of 10~16 m, and the axial stress ratio of core pile/soil-cement pile changes significantly near the depth of about 10 m. The research outcomes could provide references for the engineering design and application of the stiffly-expanded composite piles.

The structure and materials used in bridge deck pavement layers significantly impact their road performance. To design a pavement layer more suitable for cold regions, the layered modification of pavement materials was optimized based on the principle of layer function design. Firstly, materials for the surface functional layer and overall functional layer were selected using the layer function division, with lignocellulose and polyester fibers as modifiers, respectively. Secondly, the appropriate content of polyester fibers was determined through road performance tests. Finally, the choice of layered materials and appropriate modification methods were established. The results indicate that both the surface functional layer and the overall functional layer should use the same high-viscosity, high-elasticity modified asphalt, with lignocellulose and polyester fibers as modifiers, respectively. This approach avoids differences in thermal contraction coefficients of the layered materials, ensuring coordinated thermal deformation between the pavement layer and the bridge structure, thereby effectively improving the road performance of the asphalt bridge deck pavement. Furthermore, under engineering economic requirements, when the polyester fiber content is 1% of the total mixture mass, the prepared asphalt mixture's high-temperature performance increases by 7%, low-temperature performance by 23%, and water stability by 5%.

With respect to the surrounding rock collapse and water gushing in the water-rich fault, a high-speed railway tunnel in Yunnan was taken as the engineering background. The fluid-solid coupling numerical calculation of tunnel construction with the three-step method was carried out, and the deformation mechanism and groundwater seepage law of surrounding rock through water-rich fault were researched combined with the deformation field monitoring results. The results show that when the tunnel face is excavated to the water-rich fault, the rock and soil in the upper wall of the reverse fault will collapse downward, and the settlement of the arch roof will increase sharply. At the fault, the rock and soil mass of the middle and lower excavation parts cannot provide stable support for the surrounding rock, so the tunnel clearance increases first and then decreases. The groundwater mainly percolates along the step surface and the palm surface, and there is still a large pore pressure above the tunnel, so the drainage pipe can be added to lead the water into the side ditch.

In order to more accurately predict flight delays at different times of the year,flight delay prediction trends was investigated using operational and meteorological data from Atlanta Airport in the United States for the year 2023. A CA-PCA-Informer flight delay prediction model,incorporating correlation analysis (CA),principal component analysis (PCA),and the Informer model,was proposed. Mean absolute error (MAE) and root mean square error (RMSE) were utilized as evaluation metrics to assess the prediction error. The findings reveal that the CA-PCA-Informer model outperforms simpler combined models,demonstrating the lowest error compared to the CA-PCA-LSTM and CA-PCA-GRU models,with MAE and RMSE reductions of 20.2%~20.7% and 12.7%~14.1%,respectively. The CA-PCA-Informer model is particularly effective for one-hour ahead predictions,providing decision-makers with more accurate flight delay trends to enhance efficient flight operations.

The applicability of prefabricated subway station structures in inclined liquefiable sites was investigated. Based on the actual project of Shuangfeng subway station in Changchun City, the finite difference software FLAC3D was used to carry out the seismic response analysis of prefabricated subway station structures in liquefiable soil, for example, the pore water pressure of the foundation, the lateral motion of the liquefied soil, the dynamic response and uplift characteristics of the subway station structure, and the deformation characteristics of the prefabricated subway station structures were analyzed. The results show that the negative pore pressure phenomenon of pore water pressure on both sides of prefabricated subway station under inclined liquefiable site conditions is present, and the phenomenon becomes more obvious the closer the location of the station structure is to the station, and at the same time, the negative pore pressure of the soil on the left side of the structure (uphill) is significantly greater than that on the right side (downhill). The further away the foundation soil is from the station structure, the more pronounced the liquefaction is. The phenomenon of lateral slippage of the surrounding soil is significantly suppressed by prefabricated subway station structures. The principal stresses in the upslope sidewall (member C1) are greater than those in the downslope sidewall (member C2), and the principal stresses at the bottom of the upslope sidewall of the structure are greatest, so the upslope sidewall of the structure should be given priority in the seismic design.

In order to improve the fire extinguishing efficiency of forest fires and reduce the damage to forest resources and ecological environment, a three-phase class A foam extinguishing agent consisting of class A foam extinguishing agent with nano-SiO₂ particles was prepared. The effects of nano-SiO₂ mass fraction on foam stability and fire extinguishing efficacy were investigated by using the double injector method and the wood stack fire extinguishing test platform. The results show that the nano-SiO₂ significantly enhanced the foam stability and delaye the foam precipitation and foam coarsening; the three-phase class A foam extinguishing agent extinguishe the flame more quickly and efficiently under the same driving pressure without rekindling and at a lower dosage than the traditional class A foam extinguishing agent; and the three-phase class A foam extinguishing agent with 1.5% SiO₂ show the best extinguishing efficacy. The three-phase A-type foam extinguishing agent significantly improves the fire extinguishing efficiency, reduces the consumption of extinguishing agent, and has low cost, which makes it suitable for large-scale forest fires. The study provides a new solution for the efficient extinguishing of forest fires and has a wide range of practical applications.

The operational efficiency of aircraft and maximization of aviation transportation benefits have consistantly been pursued by CAAC. It has been indicated by research that the Established on RNP AR (EoR) approach plays an irreplaceable role in improving efficiency, especially for short-distance parallel runway operations, thus, it has received widespread attention in the industry. The integration of EoR approach with sorting strategies was undertaken, with the aim of minimizing flight delay time serving as the objective function, leading to the establishment of a sorting model based on EoR. The impact of EoR-based independent operation versus correlated operation on flight delay time had been compared and analyzed. Addressing the large solution space and the time-sensitive nature of large-scale flight sequencing calculations, The S-shaped function based adaptive particle swarm optimization (SA-PSO) algorithm was proposed to solve the model. Taking the Kunming Changshui International Airport terminal area as an example for case verification, the RECAT-CN operational standard was adopted for wake turbulence safety separation. The results show that, compared to correlated operations, independent EoR operations result in an approximately 38% reduction in total delays. Additionally, the algorithm proposed in the study, when operated independently under the EoR mode results in a reduction of total delays by approximately 15.3%, compared to the first come first served (FCFS) algorithm.