To investigate the impact of temperature on axial stress in large-span concrete variable-section continuous beam bridges under various wind speed fields, a method was proposed to calculate vertical temperature gradients separately based on inconsistent deck slab thickness and simulate lateral fluctuating wind speed fields using the spectral method. Firstly, vertical temperature gradient variations and their depths were calculated by employing the concrete heat-conduction equation, daily maximum and minimum temperatures, and deck slab thickness of the variable-section continuous beam bridge. Secondly, bridge modeling was performed using MIDAS Civil, and ZKH standard static live loads were simulated to represent moving train loads. Finally, static array wind loads and pulsating wind loads were applied to the bridge. The results indicate that the axial stresses in the left and right lanes obtained from the proposed method, which uses vertical temperature gradients and their depths derived from the concrete heat-conduction equation, daily temperature extremes, and bridge deck slab thickness, are larger compared to existing studies. Under the same wind speed field model, the harm to the bridge is greatest under gradient heating, followed by gradient cooling, while no temperature change results in the least impact. When the bridge is subject to the same temperature model, both the axial stress values and amplitudes of the bridge under pulsating wind loads are larger and more severe than those under no wind or static wind conditions, posing greater hazards to the bridge. The research findings can provide references for the structural design and safe operation of large-span concrete variable-section continuous beam bridges.

With the implementation of river dredging projects in China, a large amount of dredged silt has been generated. The treatment and disposal of silt have gradually attracted great attention. Using solidification technology is one of the effective ways to solve the problems caused by dredged silt. Taking the dredged silt from Beibaidang in Zhejiang as the research object, the solidified products were analyzed through X-ray diffraction (XRD), and the porosity and pore structure of the solidified silt soil were quantitatively analyzed by means of X-ray computed tomography (X-CT) and mercury intrusion porosimetry (MIP) tests. Meanwhile, it explores the mechanical variation laws and solidification mechanism of the soil under soaking and dry-wet cycling conditions. The research shows that the calcite content in the solidified soil increases with the increase of the solidifying agent dosage. The increase of ordinary sand dosage improves the small and medium-sized porosity inside the soil, but the overall porosity shows a decreasing trend. The results of water stability tests indicate that the strength and stability of the solidified silt soil are significantly improved with the increase of the solidifying agent content, and they first increase and then decrease with the increase of sand dosage.

With the expansion of the Internet scale and changes in its topological structure, network management is facing huge challenges. Segment routing (SR) protocols, especially SRv6(segment routing over IPv6), have become a research hotspot due to their high programmability and scalability. The path optimization control mechanism based on SRv6 solves the problem of avoiding and relaying specific nodes in multiple demands and scenarios to improve network performance. A path transfer scheme for fully deployed SRv6 networks was proposed, and the routing overhead was reduced through the optimization of forked paths. For some deployment networks, define the critical path and design the avoidance and relay path forwarding scheme to optimize the path forwarding efficiency. The experimental results show that when SRv6 is fully deployed, the optimization scheme can effectively reduce the depth of the segment list and the routing overhead. In some deployment networks, only a small number of SRv6 nodes can achieve performance close to that of a full SRv6 network, successfully solving the problem of evading and relaying specific nodes. The research results provide effective support for the application of SRv6 in different network deployments.

In order to study the influence of floating offshore wind power suction anchor size on the horizontal bearing capacity, based on the ABAQUS finite element software, a three-dimensional finite element model of suction anchor foundation was established by using elastic-plastic constitutive model. The results show that the increase of diameter and height can improve the horizontal bearing capacity of suction anchor, and the increase of height is more obvious. With the change of diameter and height, the position of the mooring point also needs to be adjusted accordingly. When the ratio of suction anchor diameter to height D/H>1, the position of the mooring point needs to be increased correspondingly to make it move in translation. The change of diameter will affect the pressure change of the anchor wall, while the height has little effect on the pressure change of anchor wall. The research results are used in global first offshore floating wind power + aquaculture platform “Guoneng Gongxiang Hao” and can provide a reference for relevant project design.

The previous structural seismic vulnerability analysis is generally based on the characteristics of the structure itself, it is rare to combine with the differences of engineering sites in the study area, the location differences of different engineering sites within the city are ignored. Taking Chengdu City as the research area and the three-story reinforced concrete frame structure as an example, an analysis method for the seismic vulnerability of reinforced concrete frame structures based on peak ground acceleration (PGA) and the maximum inter-story displacement angle θ_max of the structure was proposed. For three-story reinforced concrete frame structures, this method conducts dynamic time-history analysis using the interlayer shear model to obtain θ_max under each seismic response. Then, logarithmic linear fitting is performed on θ_max and its corresponding ground motion to obtain the relationship between the two. For the Chengdu area, this method takes the historical ground motion data of Chengdu as the data basis and combines PGA calculation formula to obtain the PGA of each engineering site location in Chengdu. Furthermore, taking the maximum inter-layer displacement angle as the structural damage index and PGA as the ground motion intensity index, the highest structural failure probabilities of the structure under four different performance levels of full operation, basic operation, life safety and near collapse were studied, which were 94.1%, 89.1%, 74.7% and 40.8% respectively. Moreover, the overall changing trend of the structural failure probability at each performance level of the structure decreases from the west to the east. Therefore, the seismic construction requirements for structures in the western region can be appropriately strengthened, and those for structures in the eastern region can be appropriately relaxed, so as to save economic costs. The proposed method has certain application value in reducing the losses caused by earthquakes and provides a certain theoretical basis for the seismic design of building structures.

The rudder in the coaxial twin-rotor is a complex mechatronic position-following control system, and its control accuracy plays a key role in manipulating the flight attitude. Because the common rudder is lacking in adapting to the unique flight environment of the aircraft, the accuracy of tracking declination and the stability performance need to improve. The manipulation principle and structure of micro UAV were analyzed, the mathematical models of position loop, current loop double PID steering gear control system and transition position loop Fuzzy PID steering gear control system were established respectively. Combined with the actual flight conditions, the dynamic and static characteristics of the coaxial twin-rotor steering gear control system were analyzed by using Fuzzy editor and Simulink module. The results show that the rudder control system with current loop PID and position loop Fuzzy PID control has 28.6% less overshoot, 28% less adjustment time and faster response than the dual PID control system. Meanwhile, the Fuzzy PID parameters are adjusted in real time to track the changes, which can adapt to the complex and variable flight conditions of the coaxial twin-rotor more quickly. The obtained control system based on dual-loop Fuzzy PID shows high accuracy and meets the requirements of stable, accurate and robust working under complex working conditions, which is of great significance for the control system design of coaxial dual-rotor aircraft.

The Shenzijing-Hashituo Subsag is located in the central part of the Changling fault depression in the Songliao Basin, an area with promising oil and gas exploration prospects. It represents a favorable oil and gas accumulation zone within the Songliao Basin. Understanding the tectonic evolution of this region and its influence on hydrocarbon genesis is crucial for guiding future exploration and development efforts in the Changling fault depression. Based on the structural characteristics, ancient drop of faults, activity rate and growth index method, the structural evolution of the depression was analyzed. Combined with the characteristics of stratum erosion, it was determined that the Shenzijing-Hasituo subsag was co-deposited in the early stage, and the Shahezi Formation was affected by compression and uplift at the end, resulting in overall erosion and segmentation. The uplift on the west side of the Hasituo depression was further strengthened during the Denglouku Formation period. At the same time, it is clear that the tectonic evolution of the fault depression layer in the Shenzijing depression-Hatshituo depression of the Changling Fault depression follows the longitudinal evolution law of fault depression-co-deposition-inversion. This early rapid subsidence and late inversion and uplift form a relatively favorable accumulation combination model of lower generation and upper storage. The research results can provide theoretical references for the restoration and further exploration of the ancient structure of the Changling fault depression.

The super-large cross-section tunnel is prone to large deformation when passing through soft rock stratum. The reasonable selection of excavation method is of great significance for construction safety. In order to explore the applicability of the double-side nine-step excavation method to the construction of super-large cross-section tunnels, based on a 500 m² super-large cross-section soft rock tunnel under construction in Chongqing, the mechanical properties of sandy mudstone were revealed by laboratory experiments. The deformation characteristics of surface and super-large cross-section tunnel structures were compared and analyzed by numerical simulation and field monitoring. The excavation sequence, temporary support measures and excavation step length were optimized. The results show that the stress-strain curves of sandy mudstone samples under different confining pressures and different unloading rates are similar, and the triaxial compressive strength and deformation characteristics of rock samples change significantly. With the excavation of the core rock mass of the upper step, the displacement of the super-large section tunnel is abruptly changed. When the temporary support measures are removed, the deformation of the super-large section tunnel is further aggravated. Different excavation steps cause successive disturbance of surrounding rock, resulting in different unloading rates of surrounding rock and affecting the deformation of surface and tunnel structure. The temporary transverse bracing effectively limits the convergence of the arch waist, and the convergence of the arch waist is reduced by about 10.0 mm under all the layout conditions. In addition, the shorter the length of the excavation step, the smaller the deformation of the surface and the super large section tunnel.

In order to meet the needs of fast and efficient transportation for coal mine drilling construction operations with trackless transportation conditions, a trackless rubber tyre vehicle integrated drilling rig was used to travel directly from the ground to the drilling site without the need for secondary transportation. By comparing the advantages and disadvantages of integral and articulated chassis structures, the narrow body rubber tyre chassis structure was determined based on actual underground tunnel conditions, and key performance parameters for the vehicle design were provided. By comparing the advantages and disadvantages of integral and articulated chassis structures, the narrow body rubber tyre chassis structure was determined based on actual underground tunnel conditions, and key performance parameters for the vehicle design were provided. Based on the overall technical requirements, multiple key technologies of the trackless rubber tyre vehicle were designed and analyzed, and the static load capacity and dynamic characteristics of the frame under two working conditions, namely the driving process and the drilling process, were simulated and analyzed. The simulation results show that the stress and displacement meet the design requirements of the frame load capacity during the walking and drilling processes, and it has good stability. After the installation and adjustment of the rubber wheel chassis, a climbing test and comprehensive performance test were carried out. The test shows that the whole vehicle meets the 15 ° large angle climbing condition, all data meet the standard requirements, and the performance meets the transportation needs of the coal mine drilling rig. It can adapt to the complex working conditions underground in coal mines.

In order to explore the influence of pore defects on the mechanical properties of concrete road and seek an equivalent model to replace porous concrete road to reduce computational time. Based on micromechanics methods, the effective elastic modulus, Poisson's ratio, coefficient of thermal conductivity and coefficient of thermal expansion of porous concrete were calculated. Three-dimensional double-layer concrete roads with randomly distributed, non-interference and varying sizes of spherical pores and their equivalent models were established to study their mechanical properties under three working conditions, namely, concentrated force, static vehicle load, and temperature-static vehicle load coupling, and further the simulation calculation time for each model was compared. The results show that under the coupling effect of temperature and static vehicle load, the increase of porosity has little effect on the temperature and displacement of porous concrete roads at the same depth and different times. Moreover, for the same porosity, the farther away from the pavement, the peak temperature shifts backward over time. When the porosity is within 8%, the actual porous model can be replaced by the Eshelby equivalent model, Mori-Tanaka equivalent model, or Self-Consistent equivalent model under concentrated force or static vehicle load, and by the equivalent model 2 under temperature-static vehicle load. With fixed computational power and constant porosity, the simulation time for the actual porous model far exceeds its equivalent model. Using equivalent models for research can significantly shorten the calculation time, and the computational efficiency can be approximately improved by about 99.8%.