To analyze the hydrodynamic characteristics of light beacons in wind-wave environments and propose an optimization scheme based on stress concentration points, the VOF (volume of fluid) method was used to calculate the pressure distribution on the surface of the light beacon under wave and wind conditions and the resulting deformations. The results indicate that stress concentration occurs at the base of the central support of the light beacon, with the maximum displacement at the top of the light beacon. Two optimization schemes were investigated based on these findings. In the slanted support scheme, stress concentration shifted to the top of the support, reducing by 32.2% compared to before optimization. The maximum deformation was at the base in the middle, a 40.1% reduction compared to before optimization. In the end-strengthened scheme, stress concentrated at the bottom, with a reduction of 0.08% compared to before optimization, while the maximum deformation was at the top of the light beacon, which was reduced by 23.1% compared to before optimization. It is evident that the light beacon structure with slanted supports can effectively reduce stress intensity and disperse the impact of wind and waves on other parts of the light beacon, representing a better structural optimization scheme.

Utilizing phase change materials and carrier materials to prepare phase change particles, replacing concrete aggregates for the production of phase change concrete, represents a novel technique for enhancing the durability of concrete in cold regions. In order to investigate the correlation between the compressive strength of PCC and its pore characteristics, a novel type of phase change particles with cement-encapsulated, named EPC₁₄, was prepared by using n-tetradecane (C₁₄) and EP (expanded perlite) as raw materials. Subsequently, phase change concrete (PCC-EPC₁₄) was prepared by replacing fine aggregates at an equal volume. The PCC-EPC₁₄s underwent 50, 100, 150, and 200 freeze-thaw cycles. Then, uniaxial compression tests and nuclear magnetic resonance tests were uesd to test the compressive strength and pore characteristics of the PCC-EPC₁₄s. Finally, the fractal dimension of the PCC-EPC₁₄ was calculated using fractal theory, and the relationship between compressive strength and fractal dimension was analyzed. The results show that the optimal volume replacement ratio of phase change particles to fine aggregates is 20%. At this ratio, the PCC-EPC₁₄(20%) exhibites the maximum NMR (nuclear magnetic resonance) fractal dimension, minimum porosity, and maximum compressive strength after 200 freeze-thaw cycles. Additionally, a proportional relationship is observed between compressive strength and NMR fractal dimension, while an inverse relationship is found with relaxation time signal area.

The characteristics of the reinforced soil interface are the basis of the design of the reinforced structure. The method of stitching transverse rib geotextile reinforcement is a new reinforcement technology for the improvement of traditional geotextiles. It improves the interaction of the reinforced soil interface through three-dimensional reinforcement and gives full play to the advantages of high strength of geotextiles. In order to study the influence of the number and height of transverse ribs on the characteristics of the reinforced soil interface, the discrete element numerical simulation of the direct shear test was carried out according to the indoor test results, and the mechanical response of the reinforced soil interface under different number and height of transverse ribs was analyzed from the macroscopic and mesoscopic parameters. The results show that the shear strength of the reinforced soil interface can be significantly improved by stitching the transverse rib geotextile. The shear stress-displacement curve is mainly divided into two parts: linear growth stage and stable stage. With the increase of the number and height of the transverse ribs, the overall shear strength of the geotextile increases. When the ratio of the height of the transverse ribs to the thickness of the soil layer is 0.5, the shear strength of the interface is significantly improved and the strain value on each transverse rib is more uniform. Therefore, it is recommended that the height of the transverse ribs is 0.5 times the reinforcement spacing in practical application. With the increase of the number of transverse ribs, the quasi-cohesive force increases obviously and the quasi-friction angle changes little. With the increase of the height of transverse ribs, the quasi-friction angle increases obviously and the quasi-cohesive force changes little. In the process of direct shear test, the strain of the paving part of the geotextile and the strain on the transverse rib increase with the increase of the number and height of the transverse ribs. The maximum strain is at the joint of the two. The strain of the first transverse rib is the largest and the fastest increase, which makes the joint of the transverse rib become the key of the whole system. Therefore, the height, setting position and stitching strength of the first transverse rib should be paid attention to in practical application. This study can provide a reference for the engineering application and further research of geotextiles as reinforcement materials.

The switching of power devices in servo drive can lead to bus voltage ripple, which may result in performance degradation, electromagnetic interference, and harmonic issues in permanent magnet synchronous motor AC servo systems. To address these issues, the influence of the switching process of power device on the voltage ripple of bus was analyzed and studied for the DC power supply servo drive system. Firstly, based on the working principle of PMSM (permanent magnet synchronous motor)and SVPWM (space vector pulse width modulation) algorithm, the ripple current of the busbar capacitor was analyzed. Then, according to the law of charge conservation, the relationship between the busbar capacitance, busbar voltage and current amplitude under the seven-stage and five-stage SVPWM modulation was analyzed theoretically, and its simplified expression was given. Finally, the theoretical results were verified by simulation experiments.

Establishing an accurate rolling bearing performance degradation prediction model plays a crucial role in subsequent processing such as bearing fault classification and life prediction. In order to solve the problem of inaccurate prediction of bearing performance degradation model, an IBA(improved bat algorithm) was proposed to improve the accuracy of degradation model prediction. Firstly, Cat chaotic mapping was applied to the initial position of the population to enhance the traversability of the population and improve the quality of the initial solution. Secondly, an inverse tangent-like control factor was added in the iterative process to improve the algorithm’s accuracy in finding the optimum. Finally, the position updating strategy was improved to prevent from falling into the local optimum. By comparing the results with those obtained from SVR(support vector regression machine) optimized by BA(bat algorithm), SVR optimized by particle swarm optimization algorithm, and SVR optimized by gray wolf optimization algorithm, the results show that the absolute mean error of the prediction model optimized by the IBA decreases by 70.60%, 67.19%, 55.56%, and the root-mean-square error decreases by 76.64%, 76.12%, and 76.12%, respectively. 76.64%, 76.12%, and 30.29%, respectively, further proving the accuracy of the improved prediction model.

For the research on the characteristics and main controlling factors of volcanic rock reservoirs, core observation, casting thin section identification, physical property testing and logging data analysis were utilized to conduct the study on the characteristics, distribution and main controlling factors of the Carboniferous volcanic rock reservoirs in the Junggar Basin. The results show that in the Chepaizi uplift, the Carboniferous volcanic rock reservoirs mainly developed volcanic effusion facies, explosive facies, tuffaceous facies and volcanic sedimentary facies, and the lithologies are mainly andesite, basalt, volcanic breccia, tuff and tuffaceous sandstone. The reservoir spaces are classified into connected pore type, fracture type, fracture-pore type and pore-cavity-fracture type according to the configuration relationship between pores and fractures. Affected by lithology and lithofacies, weathering and leaching effects and tectonic actions, the reservoir properties have strong heterogeneity. The dominant reservoir lithologies are andesite, volcanic breccia and tuff. A three-layer weathering crust structure composed of clay layer, hydrolysis layer and weathering and leaching layer is developed at the top of the Carboniferous, which significantly improved the reservoir physical properties. Fractures are an effective supplementary factor for reservoir development. Different from the previous studies that mainly focused on characterizing the characteristics of the dominant volcanic rock reservoirs, based on the coupled controlling effects of lithology and lithofacies, weathering and leaching, and strike-slip faults on the reservoirs, it is innovatively recognized that two dominant volcanic rock reservoir development models, namely fault-block body and fault-fracture body, are mainly developed in the study area. The research results have certain guiding significance for the exploitation of the Carboniferous oil and gas resources from east to west in the Chepaizi uplift.

In order to study the erosion behaviour of the gooseneck pipe in the drilling fluid environment and the evaluation of the surface strengthening effect, the influence of the drilling fluid density on the erosion behaviour of the gooseneck pipe and the evaluation method of the surface strengthening of the inner lumen were investigated by the finite element simulation and analysis method. The results show that: the erosion rate of gooseneck pipe is the largest in the inner diameter of the bend, and the maximum erosion rate becomes larger with the density of drilling fluid becoming higher, but the maximum erosion rate still occurs in the inner diameter of the bend. The maximum deformation displacement can be effectively reduced by 34.23% after surface strengthening of the inner lumen of the gooseneck pipe. It can be seen that the effect of drilling fluid density on the erosion behaviour of the gooseneck pipe cannot be ignored, and surface strengthening can effectively reduce the maximum deformation displacement.

With the rapid development of infrastructure projects in China, the use of anchor bolts in mining, geology, and tunnel engineering continues to increase. The non-destructive testing of anchor bolt quality is crucial for enhancing the stability and safety of engineering projects. Based on the stress wave detection method, wavelet threshold functions and STA/LTA algorithms were employed to comprehensively evaluate anchor bolt engineering. A software for non-destructive testing and intelligent analysis of anchor bolt anchorage was developed, integrating signal filtering and acquisition of anchorage parameters. Through numerical simulation analysis of anchor bolt anchorage, the lengths of anchor bolts were calculated using both manual picking and software-based arrival time extraction. The results show that the software-calculated anchor bolt lengths have an overall error controlled within 5%, offering higher precision than manual picking, which is significant for improving the safety and stability of project engineering.

Aiming at the blindness of the current coal mine roadway surrounding rock support programme and its parameter design, in order to improve the effect of roadway surrounding rock support and meet the requirements of safe and efficient production of mines, taking the Jiaoping mining area as the engineering background, the roof strength, coal gang strength, bottom plate strength, the basic top comes to press the equivalent, mining disturbance, roadway buried depth, roadway protection coal pillar width, span height ratio, top height ratio and the maximum horizontal principal stress were selected as roadway stability master control indicators, and 16 typical roadways and chambers were selected as samples, and the weights of 10 classification indicators were determined based on the analytic hierarchy process. On this basis, the stability of the sample roadway was clustered and analyzed, and the optimal classification number was selected according to the F-statistic method to divide the sample roadway into five categories: very stable, stable, basically stable, unstable and extremely unstable, and then the cluster center of the stability of the mine roadway was constructed. Finally, based on the above theory, the stability of the surrounding rock in the 2407 return wind channel of Yuhua Mine was predicted, and the targeted support measures and parameters were proposed. The results show that the classification results of 2407 return wind channel roadway stability are in line with the actual field engineering, and the deformation control effect of surrounding rock is good, which provides a strong guarantee for the safe and efficient production of the working face.

The experimental research on the dynamic response of aero-engine rotor under sudden impact load was carried out by using high-speed motor drive on the vibration table. Rotor dynamic response tests under different characteristic speeds, load sizes, impact directions, and pulse widths were completed, revealing the general rules of rotor dynamic response under sudden impact loads. The results show that the dynamic response of the rotor increases instantly and then returns to a stable state when under instantaneous impact, and it increases with the increase of the sudden impact load. Besides, the vertical dynamic response of the rotor is greater than the horizontal dynamic response, and the vertical response of the same measurement section is 4% to 46.15% greater than the horizontal response under various operating conditions. In addition, the dynamic response of the rotor under axial foundation impact is greater than that under vertical foundation impact. Within a certain range, as the pulse width of the impact load increases from 6 ms to 11 ms, the dynamic response of the rotor decreases by 2.5%~10%. The study provides a reference for the vibration response analysis of aero-engine rotors under sudden impact loads and the structural safety design of aero-engine, which has important engineering application value.